Lawn and turf

Not all grasses are created equal. In Idaho, most home lawns are composed of Kentucky bluegrass, perennial ryegrass, tall fescue, fine fescue or a combination of the four. These grasses are classified as cool-season turfgrasses and are well adapted to northern regions of the U.S. They grow rapidly in the spring and fall when soil temperatures are around 55-65°F. Their growth is slower in the summer as both air and soil temperatures rises. These four grasses differ in their adaptation to shade and cold temperature, as well as in their color, texture, maintenance requirements and growth habit.

There are two basic growth patterns of lawn grasses, bunch-type and spreading, and the growth habit affects how quickly they spread into bare areas. Bunch-type grasses grow in clumps and spread very slowly by tillers, which are secondary stems that grow vertically from the base of the plant. Spreading type grasses, in addition to tillers, produce stems that grow horizontally either underground (rhizomes) or aboveground (stolons), and can fill in bare or damaged areas much more quickly than bunch-type grasses.

So which grass should you plant if you are establishing a new lawn, renovating or re-seeding an existing lawn? Unfortunately, the answer is, “it depends.” There are many important factors that need to be considered such as the intended use of the lawn, the amount of care it will receive, and the environment. Will it be a showcase lawn for the neighbors to admire, or will it be the type of lawn that violates your subdivisions landscape covenants? Do you have pets? Will you have lots of barbecues and foot traffic on the lawn? Once you have determined the quality level and intended use, you can choose the grass best suited to your specific needs. Even if you already have a lawn established, it is important to know what type of grass you have so that you can fine tune your management practices to best suit the needs of that particular grass.

The next sections describe the four most common lawn grasses in Idaho including information about adaptation, identification characteristics, growth habit, advantages, disadvantages, management considerations and variety selection.

Kentucky bluegrass

Kentucky bluegrass (Poa pratensis) is the most widely adapted and most commonly used lawn grass in the United States. It does well in sunny areas throughout Idaho, is very cold tolerant, and will form a dense, high-quality turf when grown in full sunlight. The leaves have a characteristic boat-shaped leaf tip and a prominent midrib.  

Kentucky bluegrass has a spreading growth habit with aggressive rhizomes allowing it to form a dense sod and fill in bare spots quickly during establishment. These rhizomes also make it challenging for gardeners striving to keep this grass from creeping into adjacent flower beds. Additionally, this aggressive, spreading growth habit makes Kentucky bluegrass susceptible to thatch development especially under high fertility and moist conditions. Yearly aerification and prudent fertilization and irrigation practices will help keep thatch to a manageable level.

A major limiting factor of Kentucky bluegrass on home lawns is its lack of shade tolerance. Under heavy tree shade or on the north sides of houses that receive substantial shade during the day, it will thin and develop powdery mildew, a white, powdery fungus on the leaves. Raising the mowing height in shady areas will help some, by giving it more leaf area to catch light.

Kentucky bluegrass requires medium to high inputs of water and fertilizer depending on the desired quality level of the lawn. For most home lawns, Kentucky bluegrass should be maintained at a mowing height of 2 to 3 1/2 inches. Mow towards the higher end of the range to develop a deep root system. Kentucky bluegrass requires 2 to 5 lbs of nitrogen (N) per 1000 ft2 per season. Irrigation requirements will range from 1 to 1 1/2 inches per week in the spring to 1 1/2 to 1 1/2 inches per week in the summer. Kentucky bluegrass will tolerate extended periods of drought by going dormant as long as it is allowed to properly harden prior to the drought.

Establishment from seed can be quite slow, requiring 10 to 20 days for germination. Using a straw mulch or planting a seed mixture with a small percentage of perennial ryegrass, which germinates much faster, will provide some protection for the slower germinating Kentucky bluegrass seeds. Laying sod will bypass this germination problem, but proper care during sod grow-in is just as important as proper care during seed establishment. Kentucky bluegrass sod is readily available in Idaho from garden centers and directly from sod producers.

There are many varieties of Kentucky bluegrass available giving a wide range of disease resistance, wear tolerance and green color. Most of the grass seed available at your local garden center or lawn and garden areas of major chain stores will have varieties of superior quality. Be sure to check the label of the seed package to ensure you are buying ‘named’ varieties and not ‘variety-not-stated’. Named varieties listed on the label indicate that the variety is an improved variety and has gone through several years of testing. It is best to choose a blend of three or more Kentucky bluegrass varieties to ensure a broad resistance base to diseases.

This fact sheet originally from Colorado State University (pdf) outlines the positive and negative characteristics of Kentucky bluegrass as well as provides some management considerations.

Perennial ryegrass

Perennial ryegrass (Lolium perenne) is a bunch-type lawn grass that is commonly used in grass mixtures with Kentucky bluegrass (Poa pratensis) on home lawns and sports fields. It is very similar in color and appearance to Kentucky bluegrass.  

The leaves of perennial ryegrass do not have the boat-shaped leaf tip like Kentucky bluegrass, instead have a pointed tip with veins on the top side of the leaves that are very conspicuous. More identifying characteristics can be found. The veiny leaves make perennial ryegrass difficult to mow especially if mower blades are not kept sharp. This leaf characteristic is also what gives perennial ryegrass the traffic tolerance for use on sports fields.

Perennial ryegrass is not as cold hardy as Kentucky bluegrass and is more prone to winter kill than Kentucky bluegrass. Perennial ryegrass is considered a short-lived perennial because of its lack of cold tolerance, and it is not recommended for higher elevations of Idaho but will do very well along the lower Snake River plains.

Perennial ryegrass germinates from seed considerably faster than Kentucky bluegrass and can overwhelm the other grasses in a mixture if there is too high of a percentage (over 20%). Perennial ryegrass will not fill in bare or damaged areas as quickly due to its bunch-type growth habit. However, an advantage is it does not form thatch due to its lack of rhizomes. Perennial ryegrass is slightly more shade tolerant than Kentucky bluegrass but may thin out in shaded areas over time due to its lack of storage organs. It is also fairly drought resistant since it can develop a deep root system

Perennial ryegrass requires medium to high cultural practices and should be mowed between 2 to 3 inches. Remember to keep mower blades sharp to cut through the tough leaves. Fertility and irrigation requirements are similar to those of Kentucky bluegrass.

Sod is not available as pure perennial ryegrass, but many sod growers use perennial ryegrass in a mix with Kentucky bluegrass. Establishment of perennial ryegrass from seed is relatively easy due to its very quick germination rate. Seed at rates of 6 to 8 lbs per 1000 ft2. As with Kentucky bluegrass, many good quality varieties are available at garden centers. Avoid selecting grass mixtures with annual bluegrass, as this grass produces a poor-quality turf over time and should be used for quick, emergency use areas only to prevent soil from eroding. Make sure and select ‘named’ varieties.

Tall fescue

Tall fescue (Festuca arundinacea)), like perennial ryegrass, is a bunch-type grass with a slightly coarser leaf texture than Kentucky bluegrass and perennial ryegrass. A description of tall fescue can be found here. However, many turf-type varieties with much finer leaves are now available. Tall fescue is gaining popularity on home lawns and is used on sports fields because it's tough leaves give it good traffic tolerance.

Tall fescue is more cold tolerant than perennial ryegrass, but not as cold tolerant as Kentucky bluegrass. Be aware, though, that tall fescue may become thin in short season, higher elevation areas. It is very heat and drought resistant due to its deep, extensive root system. Tall fescue also has good shade tolerance compared with Kentucky bluegrass and perennial ryegrass. It has few insect and disease problems if managed properly. Due to its bunch-type growth habit, it forms thatch slowly and does not invade flower beds but may require overseeding on damaged or areas worn by heavy use.

Tall fescue has a wide range of cultural needs depending on use. The best quality turf is achieved at mowing heights of 2 to 3 1/2 inches. Fertility requirements are less than Kentucky bluegrass ranging from 2 to 4 pounds nitrogen (N) per 1,000 ft2 per season. The deep root system of tall fescue will allow it to draw water from deeper depths in the soil and may allow you to stretch the irrigation frequency by about a day during the summer compared with Kentucky bluegrass. However, if the root system is restricted due to poor soil conditions, tall fescue will need just as much water as Kentucky bluegrass, if not more.

Availability of tall fescue sod is more limited than Kentucky bluegrass, but seed is readily available, and germination is fast. Seed at rates of 6 to 8 pounds per 1,000 ft2. Many new turf-type tall fescue varieties are now available and as always, choose seed with ‘named’ varieties. Avoid the variety “K-31″ or “Kentucky 31″ as this is the old forage-type variety with wide blades and will result in a poor-quality lawn.

Fine fescues

The fine-leaved fescues (Festuca spp.) are generally considered low maintenance grasses because of their low nitrogen requirement and slow growth, but they can produce a dense, quality turf with proper management. The fine fescues include creeping red (Festuca rubra subp. rubra), chewings (Festuca rubra subsp. chewings) sheep (Festuca ovina) and hard (Festuca longifolia or duriuscula) fescue. All are primarily bunch-type grasses except for creeping red fescuse which has rhizomes. Fine fescues are the most shade tolerant of the cool-season grasses and are commonly used in shade mixtures with Kentucky bluegrass and/or perennial ryegrass. They are not recommended for high traffic areas because their leaves do not hold up to wear like perennial ryegrass and tall fescue and they are slow to fill in damaged areas.

Leaves of the fine fescues, as their name suggests, are very narrow, resembling a pine needle. Although they are bunch-type grasses, the fine fescues will produce thatch quickly due to the chemical makeup of their leaves and stems that makes them difficult to break down.

Fine fescue leaves have a needle-like appearance.

The fine fescues are very drought resistant, but do not tolerate heat very well and may go dormant in the middle of the summer when temperatures reach into the 90s even under well-watered conditions. However, they are very cold tolerant and tolerate poor soil conditions. Mowing can be difficult for the fine fescues because the leaves tend to lay over, so they are missed by the mower blade. For medium quality, dense lawns, the fine fescues should be mowed closer to 2 inches and up to 2½ inches under shady areas. Fertility requirements are quite low, ranging from 1/2 to 2 lbs nitrogen (N) per 1000 ft² per year. For true low maintenance areas, sheep and hard fescue are better adapted, while under traditional home lawn conditions and in mixtures with Kentucky bluegrass, creeping red and chewings are better.

Sod is not available for the fine fescues except under special and specific conditions. Seed is readily available and several varieties are currently in use. Seeding rates should be in the range of 5 to 7 lbs per 1000 ft2. Germination is fairly rapid although seedling maturation is quite slow, so frequent irrigation may need to be extended longer than for the establishment of other cool-season grasses.

Other grasses: Buffalo grass

Buffalo grass (Buchloë dactyloides) is a warm-season grass native to the western plains of the U.S. Because it is a warm-season grass, it grows quite differently than the cool-season grasses. It grows slowly in the spring and fall and will go dormant for up to seven months of the year in Idaho and other northern parts of the U.S. It turns a purple-gray color after a killing frost in the fall and will remain dormant until late spring. The leaves are hairy and gray green in color and fine textured. Buffalo grass has a spreading growth habit with aggressive stolons that are difficult to contain.

The big advantage of buffalo grass is its excellent heat and drought tolerance as a result of its deep root system and very low water use rate. It also has a very low nitrogen fertilizer requirement and is slow growing requiring less frequent mowing. The major disadvantage of buffalo grass is its very short growing season — mid May to approximately mid-September. It is not recommended for high elevation areas (>6,000 ft). Weed encroachment can be a major problem since sunlight may be able to penetrate dormant turf, especially in thinner areas. It is not shade tolerant and does not tolerate heavy traffic.

Buffalo grass can be established from sod or plugs, but availability is very limited. Seed is also more difficult to find and is quite expensive compared with the cool-season grasses. The seed is inside of a hard burr that should be treated with a KNO3 (potassium nitrate), a non-toxic salt to help soften the seed coat and break dormancy. When seeding, it is important to ensure good soil contact and cover seeds to a depth of 1/4 to 1/2 inch. The large burr is more difficult to cover with soil, so extra care should be taken at this step with additional raking if needed. It is important to remember that buffalo grass is only drought resistant once established. New seedlings are still susceptible to drying until they can develop an adequate root system. This may take one full season to attain. Buffalo grass should be seeded in late May or early June with a mature stand possible by September.

Once established, buffalo grass should be mowed from 2 1/2 to 4 inches for a higher quality lawn. Mowing may be required only every two to three weeks. Fertilization requirements are less than 2 lbs of nitrogen (N) per 1,000 ft2 per year with applications made during the summer months, unlike the cool-season grasses. Buffalo grass requires about 1 to 2 inches of water every two to four weeks to produce acceptable quality.

Seed mixtures/blends

Most pre-packaged seed you buy in a store will be either a mixture of several types of grasses (Kentucky bluegrass + perennial ryegrass) or a blend of several varieties of one type of grass (Kentucky bluegrass: ‘Baron’ + ‘Chateau’ + ‘Courtyard’).

Mixtures are designed to take advantage of the characteristics of several types of grasses for use in areas with varying conditions. The most common example of a mixture is a sun/shade mix. This type of seed mixture may contain Kentucky bluegrass and creeping red fescue. In sunny locations, the Kentucky bluegrass will thrive and dominate the stand, while in shaded areas the fine fescue will dominate. Perennial ryegrass is commonly added to sun/shade mixtures as a nursegrass since it germinates rapidly and provides protection for the slower emerging grasses. The percentage of perennial ryegrass in a mixture should be less than 20% so that it does not overwhelm the other grasses. Blends of several varieties of one type of grass are designed to take advantage of the desirable characteristics of each variety, for example, disease resistance. There are hundreds of varieties available for each of the grass types and blending several of these together helps guard against diseases as well as increases the environmental adaptation of the grass. Make sure to check the label when purchasing blends and avoid buying those with ‘variety not stated’ since these tend to be older, outdated varieties.

Seed sources

Many nurseries and home garden centers provide grass seed. A listing of nursery members of the Idaho Nursery and Landscape Association can be found at their website.  

The most important part of establishing a lawn is proper soil preparation. One of the main reasons for turfgrass failure is a poorly prepared site with inadequate soil characteristics. New construction in subdivisions requires removal of topsoil to allow contouring for adequate storm water drainage. Too often topsoil is not placed back around homes prior to lawn installation. Understanding the requirements of good seedbed preparation will help the long-term success of a lawn.

Using good quality seed is also very important. Read the section on turfgrass selection to choose the correct type of grass for your application. Additionally, make sure to purchase seed that has a high germination rate (85% minimum) and contains minimal weed seed and “other crop seed.”

The best time to seed cool season grasses in Idaho is late summer and fall for several reasons. Soil temperatures are optimum for seed germination, there is less competition from summer annual weeds, and the newly emerged grass seedlings will not be exposed to summer heat. It is possible to seed a lawn successfully in the spring, but extra care will be needed to help the seedlings along during the hot summer temperatures.

The establishment process includes site preparation/rough grading, seedbed preparation, seeding/sodding, post seeding/sodding care.

Site preparation for lawns and turf

Remove rocks and debris from area to be seeded.

Large pieces of leftover construction lumber or tree stumps that are covered with soil will eventually decompose leaving depressions in the lawn and can also lead to the fungus that causes fairy ring. Grade the area sloping away from house foundation at a minimum of 2% (1/4-inch fall for every 12-inch run) to allow for adequate drainage of water. At this point in the process is a good time to install an underground irrigation system. However, before installing the system, be sure you know where your landscape features such as trees and flowerbeds will be located so the trees will not later interfere with the irrigation system, or the flowerbeds will be properly watered. Before planting a lawn is also a good time to control deep-rooted perennial weeds such as quackgrass, Canada thistle and field bindweed.

After properly grading the subsoil, topsoil should be added if not already in adequate amounts on the site (minimum of 6 inches). The final topsoil grade should match the contour of the underlying subgrade.

Seedbed preparation

Add soil amendments such as compost if the soil is low in organic matter. A soil test will tell you whether the soil requires organic matter or other nutrients. Incorporate the fertilizer and soil amendments to a depth of at least 6 inches.

After the tillage operation, smooth the surface with a rake for smaller areas or drag a piece of chain-link fence behind a riding mower or four-wheeler for larger areas. The final seedbed should be moist, slightly firm leaving a one-quarter inch footprint. During this final raking operation, spread a starter fertilizer and rake into the area. A general rule of thumb is to add a starter fertilizer with adequate phosphorus at a rate of 1 lb nitrogen per 1000 ft.

Seeding

Seed the area in two directions to ensure adequate coverage, then rake lightly to place the seed at about one-quarter inch depth. A metal leaf rake works well. Lightly roll the entire area to ensure good seed-to-soil contact using a lightweight roller. Apply a straw mulch, especially on sloped areas, to prevent erosion and help retain moisture as well as buffer temperatures while the seedlings are emerging. It is not necessary to rake away the mulch after emergence if it was applied at the proper rate.

Post planting care

Irrigate the area lightly and frequently to keep the surface moist during the germination process. This may require two to three light waterings each day especially during periods of hot, dry weather. A mid-morning irrigation and one at mid-afternoon may be enough to keep the surface moist, but additional irrigation may be needed in the early evening as well. Once the seedlings have grown to a height of 1 inch, the irrigation can become less frequent, and the amount of water applied can be increased.

The first mowing should be when the seedlings reach just past the desired mowing height. Do not apply any herbicide to the new seeding until the grass has been mowed at least four times. If seeding was done in the fall, an herbicide application could be skipped since all annual weeds will die during the winter. If perennial broadleaf weeds are seen in the fall, they should be controlled but still wait for a minimum of four mowing's before applying an herbicide.

Sodding

The seedbed should be prepared the same way for sod as for seed. It is also very important that the soil be moist (not wet) at the time of installation to encourage root growth. Sod that is placed on dry soil will have a difficult time growing new roots. Lay sod pieces in a brick-like pattern with edges placed tightly against each other. On sloped areas, place the sod horizontally across the slope and use stakes for steep areas to avoid slippage. Working in long straight lines will help reduce labor and waste. Roll the area lightly after installation to remove air pockets and provide good root-to-soil contact.

Newly sodded areas need frequent irrigation because the grass lacks a root system. An initial irrigation of about one-half to 1 inch should be applied, followed by enough water to keep the soil below the sod moist on a daily basis. For about the first two weeks while the roots are growing, keep checking the soil moisture by lifting up a corner of sod to ensure adequate moisture is present. Avoid traffic in the area for at least four weeks to ensure adequate root growth. Sometime during the first year following establishment, a newly sodded lawn should be core aerified to help eliminate any soil layers created between the soil on the sod and the seedbed. Soil layers make it difficult for water and nutrients to move properly throughout the soil profile.

More information about starting a lawn can be found in Starting a home lawn, CIS 1062.

A properly fertilized lawn will not only look nice but will be more resistant to diseases like leaf rust and will also fend off weeds by out-competing them. Three basic questions to ask when it comes to lawn fertilization are:

• How much should I apply
• When should I apply it and  
• What kind of fertilizer should I use?

Remember to consider the desired quality level you want for your lawn when considering these questions. If you want a "low maintenance" lawn, you need to be sure you have a grass species that can tolerate low fertility and minimal irrigation.

Main nutrients for lawns and turfgrass

It is important to understand the main nutrients that lawn grasses require for adequate growth.

Nitrogen is perhaps the most important nutrient as it helps grass produce green, healthy leaves. Since leaves are the energy-making factories of the plant, it is important that enough nitrogen be provided to maximize their energy making capabilities without causing an over production of leaves.

Phosphorus is important for strong root growth and is very important during establishment. Since phosphorus does not move readily in the soil and new grass seedlings have limited root systems, providing some phosphorus fertilizer during establishment is very important. Mature lawns have very fibrous root systems and are much more adept at mining phosphorus from the soil. Generally, unless very deficient, fertilizers with low percentages of phosphorus are used for lawns.

Potassium is very important for lawns and helps grasses respond to heat and drought stress. Although deficiencies in potassium are difficult to detect, the importance of potassium in stress management should not be overlooked. Unless a soil test reveals that potassium is very abundant, fertilizers with percentages of potassium similar to nitrogen should be used.

Iron is another nutrient that is important, especially in southern Idaho soils. The high pH soils of southern Idaho tie up iron making it unavailable to the plant causing it to become yellow (iron chlorosis). Iron-containing fertilizers can help alleviate iron chlorosis, but make sure of the type of iron you are buying. Iron in the forms of ferrous sulfate or iron sulfate are absorbed by the leaves. If washed into the soil, the iron quickly changes form and becomes unavailable to the plant. Iron in the form of iron chelate (Fe-DTPA, Fe-EDTA, Fe-EDDHA, and Fe-HEDTA), are more effective as soil applied fertilizers. Iron in this form is available to the plant even when in contact with the soil and the effect is much longer lasting than the foliar-absorbed iron fertilizers.

How much fertilizer to apply to lawns and turfgrass

A general recommendation for cool-season grasses is a range from 0.5 to 5 lbs of nitrogen (N) per 1000 ft2 per season depending on the desired level of quality. Low input lawns with tall fescue or fine fescue will only require about 2 lbs N per 1000 ft2 per season or less, while low input lawns of Kentucky bluegrass and/or perennial ryegrass will require approximately 3 lbs N per 1000 ft2 per season. Medium to high input lawns of Kentucky bluegrass and perennial ryegrass will require 3-5 lbs N per 1000 ft2.

When to apply fertilizer to lawns and turfgrass

To understand the timing of lawn fertilization, it is important to understand the seasonal growth pattern of a grass plant. In the spring, grasses are coming out of winter dormancy and begin rapid growth using stored energy reserves from last year. Grasses that are over-fertilized with nitrogen in the spring will spend too much of those energy reserves on leaf growth and will not have enough left over to take them through summer’s heat and drought stress. All that is needed in the spring is to supply the grass with just enough nitrogen fertilizer to prevent it from becoming chlorotic (very light green to yellow in color).

As temperatures rise in the summer, leaf and root growth start to slow. Over-fertilization at this time could be very detrimental to the health of the grass and even cause areas to die. Avoid fertilizing during the summer except to prevent chlorosis. Very light applications and use of a slow-release fertilizer will help keep the grass green in the summer without burning or damaging the lawn.

As temperatures cool and hours of light per day diminishes in late summer to early fall, grasses begin preparing for winter by sending their energy reserves to their rhizomes and roots. A fertilizer application at this time will help the plant maximize energy production, and most of the energy will be sent to storage instead of being used for leaf growth.

Table 1 gives recommendations for various grasses at various times of the year. Keep in mind that the March application may be omitted if green-up is satisfactory, and a late fall application was made the previous year. In this case, a single application of 1 lb N per 1000 ft2 can be made. Use slow-release fertilizers for a late fall application and on sandy soils throughout the year to reduce nitrogen leaching. Additionally, if you are using a mulching mower or otherwise returning clippings to the lawn, you may be able to cut back the nitrogen by about one fourth.

Table 1. Nitrogen fertilization schedule for home lawns. (Adapted from Colorado State University lawn fertilization extension fact sheet).

What kind of fertilizer to apply to lawns and turfgrass

There are many types of fertilizer available for purchase, and it can be quite confusing trying to choose the correct one. Understanding the nutrient requirements of the grass as described above will help narrow the choices. Understanding the different types of fertilizers will help narrow the choices even further.

Fertilizers can be divided into two major groups, fast release and slow release. This refers to how quickly the nitrogen is released and made available to the plant. You may also have heard about organic vs. inorganic fertilizers. This refers to the chemical composition of the fertilizer. It is important to understand that the term “organic” means the fertilizer contains carbon in the chemical structure. Organic fertilizers include natural materials such as sewage-based products like Milorganite®, animal by-products like manures and bone meals, and plant by-products like corn gluten meal. There are also synthetic organics like urea which is very common in the agricultural industry, but less so in the turf industry because of its very fast release and high burn properties. There are, however, also many forms of urea that have been developed to slow its release and lower its burn potential.

Fast-release fertilizers

Fast-release fertilizers are quickly released into the soil and available for uptake by the plant. The advantages of these materials are that they are relatively inexpensive, are not dependent on temperature for release and give the grass a quick response. The disadvantages of fast-release fertilizers are that they are more likely to burn the turf if applied incorrectly (during hot periods or at too high of a rate), the response is generally short lived, and because of their water solubility they are more likely to leach through sandy soils or runoff of compacted soils. Several light applications can compensate for the quick, short-lived response, but this requires more labor.

Slow-release fertilizers

Slow-release fertilizers cause a more uniform color and growth response over a longer period of time than the fast-release fertilizers. They are also less likely burn the grass. Some products will release nitrogen into the soil slowly over several weeks or even months. All the natural products like manures, bone meals, etc. are slow-release fertilizers and require soil microbes to release the nitrogen to make it available to the plant. When applied to cool soil temperatures, below 50° F, the grass may not respond at all to the application. Most of the natural slow-release fertilizers are quite low in nitrogen content, so it will take more product to apply the same rate of actual nitrogen as it would with a synthetic fertilizer with a higher nitrogen content. Other types of slow-release fertilizers include sulfur-coated urea, polycoated urea and other urea-based products. These products tend to be more expensive but provide a good uniform turf response.

How to apply fertilizer to lawns and turfgrass

Drop spreaders and rotary spreaders are available for fertilizer applications on home lawns. Both can do an effective job if used correctly. Drop spreaders, as the name implies, drops the fertilizer material directly from the spreader onto the lawn placing the fertilizer precisely in the desired location. Drop spreaders take longer because you must cover every square inch with the spreader.

With rotary spreaders, the fertilizer material is spun out over a large area.  A lawn can be fertilized more quickly with a rotary spreader because of the area covered in one pass, but some fertilizer invariably gets thrown where it is not wanted such as sidewalks and streets. Make sure to sweep up fertilizer off sidewalks as the prills can cause stains and can wash into storm drains.

Regardless of the type of spreader used, it is good practice to cut the application rate in half and apply the fertilizer in two directions to avoid stripping patterns.

Low maintenance lawns

Low maintenance can have several meanings. To some people, low maintenance means no maintenance at all. In this case the grass is left to grow much like a meadow or grass along a highway, etc. To others, low maintenance means little if any fertilization, minimal irrigation, infrequent mowing, and pest control only if absolutely necessary. The latter may be what most people would prefer in a home lawn as long as it results in acceptable quality. It is important to understand that the quality expectations of low-maintenance lawns should not be very high since minimal inputs will result in a turf of minimal quality.

The simple, everyday task of mowing your yard is commonly overlooked in terms of its importance to the overall health of the lawn. If done correctly, mowing will not only make a lawn look nice but will keep it healthy and more resistant to stress and invasion from weeds, insects and diseases.

Mowing height

Although there are differences in optimal mowing heights among different types of grasses, for most home lawn situations, a mowing height of 3 inches is a good target. Some grasses can tolerate lower mowing heights, such as perennial ryegrass and Kentucky bluegrass, but mowing too low decrease root growth and makes the lawn more susceptible to drought and heat stress as well as increases the incidence of weeds and diseases. Never mow your lawn lower than 2 inches.

Lower mowing heights require higher management inputs. Higher mowing heights encourage deeper roots.  

Some people recommend lowering the mowing height in the spring and again in the fall, but this is not absolutely necessary. It is more important to maintain the proper mowing height and to mow frequently. Continue mowing late into the fall until the grass has stopped growing, sometimes as late as late November. This will remove excess debris and decrease the chance of snow mold. Raising the mowing height in the summer is good practice. This higher mowing height encourages deeper root growth and increases the lawn’s resistance to drought stress. Even a 1/4-inch adjustment (one wheel notch on most rotary mowers) will make a big difference in the health of the grass.

Check your owner’s manual for the correct height setting or place the mower on a flat surface and use a short ruler to check the distance between the mower blade and the ground. Be sure mower is off and disconnect the spark plus when making any adjustments and when checking blade height.

How often should I mow?

The rule to use for determining how often to mow is the 1/3 rule which states: Never remove more than 1/3 of the leaf blade height at any one mowing. So, if your mower is set at 3 inches, you should mow when your grass reaches 4.5 inches. Violating this rule not only scalps the grass and makes it look unsightly but also puts the grass under stress. If you just can’t seem to keep up with the growth of the grass, try raising the height a notch and slowly lowering the mowing height over time to get back at the desired height.

Grass clippings

Contrary to popular belief, grass clippings are not a major contributor to thatch. Grass clippings are composed primarily of water and breakdown fairly rapidly in the soil. As long as you are following the 1/3-rule, the clippings will not accumulate on the lawn and should filter back into the lawn. If you are not mowing frequently enough, large clumps of clippings on the surface should be removed because they will decompose slowly and may smother the grass. A hint in dealing with excess clippings is to let the clumps of grass dry for an hour or two and mow them again. This will help break up the clippings into smaller pieces and distribute them more evenly over the lawn.

For additional information on grass clippings and their management see the University of Idaho’s publication: Don’t bag it! Recycle your grass clippings, CIS 1016 (pdf).

Mowers and maintenance

Rotary mowers are the most common mower for homeowners. It is important to keep the mower blade sharp so the grass blades are cut cleanly. Too often this is overlooked, causing the blades to tear and rip instead of being smoothly cut off. Ripping leaves blades open to diseases and stunts the grass. Sharpen the mower blade approximately every four to six weeks depending on the size of your lawn. If sharpening the blade yourself, use a file and follow the original bevel of the cutting edge, moving the file towards the cutting edge. Test the blade for balance by placing a screwdriver through the center hole checking to be sure the blade remains horizontal. If not, you may need to remove metal from the non-cutting edge of heavier side until balance is reached.

Reel mowers are not as common and cut grass blades with a scissors-type action. These types of mowers are much more difficult to sharpen at home. Additionally, it is important that the stationary bed knife be properly adjusted to the cutting reel for a proper cut. Check with a hardware store or lawn mower mechanic for proper adjustment and sharpening of reel mowers.

Tuck in your lawn for the winter

There is a little nip in the air, indicating the approach of fall. This means it’s time to begin winter preparations for your yard and garden. In this process, the lawn sometimes gets ignored because it stops growing and seems to present few demands. However, fall is a key time of the year in lawn growth, and you can have a definite impact on how it looks next spring if you take time to complete a few simple tasks.

Cleaning up leaves is more than making the lawn look nice. If left on the ground during the winter, leaves become wet, mat down, and smother the grass during the winter. Grass does not completely stop growing, even in the dead of winter. As it grows, grass needs to breath and matted down leaves reduces air flow. Leaves also cause quite a bit of shading during the fall and early winter before snowfall when the grass is trying to store up energy. Just as chipmunks store food underground for the winter, grass uses sunlight to make food, which it stores in its stems growing underground. If you have just a few leaves and a mulching mower, mulching the leaves and letting them filter into the grass is fine as long as they are not too thick.

Speaking of mowing, it is a good idea to continue mowing your lawn well into October and maybe even into November. These late mowings will not only help chop up any leaves you may have missed, but more importantly, will help prevent winter diseases. You may have heard the advice to lower the mowing height a notch or two on your last mowing. This can help alleviate disease but be careful not to overdo it. You are better off leaving the mowing height the same, but mow more often into late fall instead.

Fertilizing during late fall also is a good idea since the grass, as we mentioned above, is still growing underground, even though leaf growth has slowed considerably or stopped. Since the underground part of grass is what allows it to make it through the cold winter and green up in the spring, a light late fall application is a good idea. Again, be careful not to overdo it. Apply no more than 1 lb of nitrogen (N) per 1000 ft2.

If you have an automatic irrigation system and have not touched the timer since the summer months, now is the time to do so. Grass uses much less water in the fall than during the heat of the summer, less than half as much. That means you may need to irrigate your lawn only about every 10 days depending on soil type. Depending on your location, you may want to irrigate your lawn until the end of October or even into the second week of November. In colder areas of Idaho, freezing temperatures may dictate stopping irrigation before the end of October. A final deep watering just before you winterize your irrigation system is a good idea. This will help prevent winter desiccation damage to your lawn especially if we have a winter without much snow cover.

What about controlling those troublesome perennial weeds like dandelions? Fall is the best time to kill them. As with the grass, perennial weeds are preparing for winter and sending food reserves underground. Applying herbicide around the time of the first fall frost will be most effective.

Following these year-end practices will help to ensure winter survival and improve the lawn’s appearance next year.

Your home lawn, like any other plant, needs water to grow and remain healthy and in Idaho that means irrigation will be needed. Lawns that become water stressed take on a gray to purplish-green color. Footprints on the grass also become more obvious when grass is stressed. The amount of water to apply at any one time and how often to water depends on several factors including soil type, time of year or weather conditions and the type of grass. Remember to irrigate early in the morning to take advantage of reduced wind, reduced evaporative losses, and usually reduced demand on municipal water systems.

A thorough discussion of how to properly water a lawn may be found in the UI Extension publication Water home lawns: how much and how often, CIS 1157.

Watering for the type of grass

Kentucky bluegrass and perennial ryegrass lawns may require up to 2 inches of water per week in the heat of the summer, but only about 1 inch in the cooler spring and fall. Turf-type tall fescue which uses the same or more water than Kentucky bluegrass may not need to be watered as frequently because it has deeper roots, so it has a larger soil volume from which to absorb water. Buffalo grass, at the other end of the scale, uses very little water and has a deep root system, so it can get by without water for several weeks.

Lawn watering and time of year/weather conditions

During the spring in April to mid-May when temperatures are still cool, most cool-season lawns in Idaho will use about one inch of water each week. From about late May to mid-August, lawns will use about 2 inches of water per week or slightly more. Then, from mid-August to late September they use just over one inch of water. During periods when significant amounts of precipitation is received, lawn sprinklers systems should be turned off. There is no need to irrigate when the soil is already filled to capacity.

Depending on the year and the onset of winter, grasses will still use close to an inch per week in October, and it is important to keep the soil moist, not overly wet, but moist going into winter. This will help prevent winter desiccation damage.

Lawns with significant shade and wind protection will not need as much water but remember that the grass will be competing with tree roots for water and nutrients, so extra attention needs to be given to these landscapes.

Lawn watering for different types of soil

Whether you have a sandy or clay soil will have a huge influence on the watering practices for your lawn. Sandy soils do not hold very much water and, therefore, lawns growing in sandy soils will need to be watered more frequently. The grass will still use the same amount of water per week, but if the soil cannot hold very much water, you will need to irrigate more frequently. Loamy and clay soils can hold more water than sandy ones and, therefore, lawns growing in clay type soils will not need to be irrigated quite as often.

In either case, apply enough water to penetrate the soil to the depth of the grass roots. Use a shovel or soil probe to determine rooting depth. For most clay type soils, it may take 1 to 1 1/4 inches of water to fill the soil to a depth of 12 inches. For sandy soils, only 1/4-3/4 inch of water is all that may be necessary to fill the soil to a depth of 12 inches. Use a screwdriver to check moisture depth. The screwdriver should easily penetrate the soil to the desired depth you want the water.

In sloped areas, lawns with heavy thatch, or lawns growing in clay or compacted soils, water may need to be applied in small amounts separated by one-half hour increments to allow for adequate water infiltration and to prevent run-off.

Sprinkler systems

Whether you are moving hoses and sprinklers or you have an automatic irrigation system, it is important to understand how much water your system is delivering in a given time period. One simple method to determine this is to set out several catch cans or rain gauges over the area to be irrigated. Run the system for 20 minutes, or a known amount of time, and measure the amount collected. Take an average of the can measurements but also make note of those that are way off the average. This will tell you that you either have a nozzle problem or a rotating head that is stuck, etc. The average measurement can be converted to inches of water per hour, and you can use this information to determine how long to run your system on a particular day. As mentioned above, a lawn’s water needs change with the season, so you should change your automatic sprinkler timers to deliver the correct amount of water depending on the time of year. In the spring, for example, you may need to water enough to replace 1 inch of water every six days, but in the summer when the grass is using more water, you may need to water every three to four days. Adjusting the timer several times during the season will reduce water waste and give the grass exactly what it needs.

While the system is running, it is a good idea to look for problems with sprinkler heads such as clogged nozzles or rotating heads stuck in one position. Clogged nozzles can be cleaned by unscrewing the nozzle or may involve unscrewing a set screw and pulling out the nozzle with needle nose pliers. On some sprinkler heads, the orifice may be replaced. However, if you don’t have a replacement, be careful not to damage the orifice. Splinker heads that do not rotate may simply need to be cleaned but usually need to be replaced as damage to the internal gears could also be a problem. Check your system each spring, taking the time to see each sprinkler operates to its full range since sometimes a head will get stuck at one end of the arc and not the other. Also, be sure the sprinkler heads are in a vertical position, so the water is being distributed as designed.

The University of Idaho publication Watering home lawns and landscapes, CIS 1098, provides a more detailed discussion on soil variables as well as an in-depth discussion on proper use of automated irrigation systems.

The larval stage of several insects causes damage to home lawns. The larvae feed on roots and underground stems of grass. A thick, healthy lawn may not be resistant to insects but will be better able to recover from injury and will be able to tolerate some damage without it being noticeable.

If you suspect insect injury, look closely in the thatch layer and top 1-2 inches of soil for larvae. Make sure you have correctly identified the insect and understand its lifecycle to determine the best course of action for control.

Billbugs

Billbugs are perhaps the most common insect affecting home lawns in Idaho. The adults, which are about 1/4 inch long, can be seen in the spring, walking along sidewalks, especially on the southern sides of buildings.

The adults are black weevils, have a long snout and will play dead when disturbed. The adults do very little damage, but in the larval stage billbugs eat grass stems and roots. Adults become active when soil temperatures reach 55ºF, usually early to mid-May. The larvae are small (1/8-1/4 inch long), white, legless grubs with a brown head.

Lawns damaged by billbugs look like they are drought stressed because the grass blades are basically severed from the roots. Grass blades can be easily pulled out by hand with a light tug. A healthy, vigorously growing lawn will recover from moderate billbug damage, and symptoms may go unnoticed. However, under-fertilized lawns or lawns that are otherwise stressed will be more susceptible to billbug damage.

Control. If you have areas with known billbug problems, control measures should be targeted against adults in the spring when they are active and seen crawling along sidewalks or other exposed areas. Waiting until damage is visible may be too late since the damage has already been done. If targeting larvae, good coverage and movement of the insecticide past the thatch layer is very important. Since adults are on the surface of the turf, they are more easily contacted with insecticides.

White grubs

White grubs are the larval stage of a beetle known as scarab beetles or more commonly as May/June beetles and masked chafers. White grubs have a characteristic “C” shape, are creamy white, with three pairs of legs and grow to a size of up to 1 to 1 1/4 inches long.

White grubs feed on grass roots causing severe wilting and eventually death of affected lawns. The sod will tend to lift away when pulled, but grass blades will generally stay intact since the grubs have mainly eaten roots. Additionally, skunks and raccoons in search of larvae will cause considerable damage as a result of their digging and feeding on grubs.

Grubs are generally found in the top inch or so of the soil and will go much deeper during the winter months. Masked chafer grubs have a one-year life cycle overwintering as larvae with the adults emerging in mid to late June.

The May/June beetles on the other hand have a three-year life cycle with adults emerging in May and June, laying eggs and the larvae feeding during the summer and overwintering. The second year, when most of the damage occurs, the grubs feed throughout the summer. In the third year, the grubs complete their development in the spring and early summer, forming pupae and adults the following year to start the cycle again.

Control. Many insecticides are labeled for white grub control; however, it is very difficult to control white grubs because of the difficulty of getting the chemical into the soil where they are active. Excessive thatch can impede the movement of the chemical into the root zone where grubs are feeding. Core aeration can help increase the effectiveness of insecticide applications. Proper watering will also help, but it is important not to over-water. Over-watering can actually decrease the effectiveness of insecticides.

Earthworms

Earthworms and night crawlers are the main cause of bumpy lawns, a common complaint of many homeowners. Worms leave castings or small mounds of soil on the soil surface. These mounds soon dry and harden causing an uneven surface, which can be somewhat bothersome during mowing operations. It is important to remember that the benefits of earthworms far outweigh the nuisance caused by these castings. Earthworms help decompose thatch, improve water and air movement and soil structure for good root growth. Earthworms are indeed a good indicator of fertile soil.

Extremely bumpy lawns may also indicate other problems such as a thin turf stand due to a poor fertilization program. Following good fertility and watering guidelines will keep a lawn growing vigorously and will make bumps less noticeable.

In severely bumpy lawns, rolling in conjunction with aerifying may help reduce the problem, but generally, lawn rolling is not advised since it can lead to soil compaction.

Lawn diseases

Home lawns in southern Idaho are generally not faced with many disease problems because of the dry climate. Improper fertility or irrigation practices are generally the main cause of disease problems. Cool, overcast weather conditions or areas in a lawn with excessive shade also can contribute to disease outbreaks. Generally, however, a properly managed lawn will be resistant to severe disease outbreaks.

Powdery mildew

Shady areas with Kentucky bluegrass are especially susceptible to powdery mildew. Powdery mildew appears as a white, powdery mass on grass blades, and large affected areas appear as if they have been dusted with flour or talcum powder. It is favored by cool, humid, shady conditions and may even appear after cloudy weather. Poor air circulation and heavy fertilization worsen the problem.

Control. If trees are causing shade and if possible, trim trees to minimize shade and improve air circulation. Powdery mildew is rarely serious enough to warrant control with fungicides. Overseed shady areas with shade tolerant grasses such as fine fescues or tall fescue.

Additional close up pictures and disease descriptions can be found at www.ipm.iastate.edu/.

Rust

Rust is an orange-colored fungus that affects the grass blades. Heavily infested lawns will leave rust-colored dust on shoes and clothing. Rust is usually a result of under fertilized and/or drought stressed turf, and the disease is favored by cloudy, overcast conditions. Light, frequent watering will keep leaf blades wet and also increase the development of rust.

Control. Generally, good fertilization and watering practices will prevent rust from occurring. Preventative fungicides are available, but generally not warranted for home lawns.

Fairy ring

Dark circles or partial circles of lush green grass in a lawn are caused by mushroom type fungi living in the soil. These dark circles of grass are commonly referred to as fairy rings. Sometimes mushrooms will appear following wet, humid weather. In severe cases, a ring of dead grass will appear inside the ring of green grass.

The fungus that causes fairy ring grows on organic matter buried in the soil. As the fungus breaks down organic matter, nitrogen is released causing the green lush growth. In some cases, the growth of the fungus is so thick in the soil that water cannot penetrate, causing the grass to become drought stressed and die.

Control. Prevention of fairy ring involves removal of tree stumps and other wood materials from a lawn site prior to establishment. If fairy ring still appears, it can be very difficult to remove the fungus entirely. Core aeration and hand watering the affected area will help move water into the affected soil and help introduce other microorganisms that will compete with the fungus. Make sure to clean aeration equipment to avoid introducing the fungus to other areas of the lawn. Proper fertility and watering practices will help reduce the severity of the symptoms and in some cases prevent fairy ring from developing. Fungicide drenches have shown irregular success and are generally not recommended for home lawns. Severe fairy rings with large areas of dead grass may warrant removal of grass and soil from the rings followed by introducing new soil and re-seeding the area.

Weeds

Most weed problems in lawns are associated with a weak, thin turf. A thin turf is easily pushed aside by aggressive weeds which can become worse over time. Make sure to follow good fertilization, irrigation and mowing guidelines to build a thick, vigorously growing lawn. Heavy weed populations are usually an indication of some other inherent problem with the lawn.

Some perennial weeds, like white clover, can still become problems even in well managed lawns. Many herbicides are available to effectively control weeds in lawns, but their success largely depends on proper application, and perhaps more importantly, on correct timing. Knowing what weeds you have will help you determine the best time of the year to control them.

Realize that it is impossible to eradicate all weeds from a lawn even with herbicide use. Learn to tolerate some weeds in your lawn and avoid indiscriminate use of herbicides which can injure trees, surrounding landscape plants and even the lawn itself.

Photographs of many weeds can be found at WSSA’s photo gallery.

Perennial broadleaf weeds

Some common perennial broadleaf weeds in home lawns include dandelion, field bindweed (also called morning glory), white clover, curly dock, ground ivy, Canada thistle, broadleaf plantain, buckhorn plantain and yarrow. Make sure to properly identify the weeds before choosing herbicides for control. University of Idaho extension educators, master gardeners and nursery personnel can help you with correct identification.

Broadleaf weeds can be controlled with postemergence herbicides (a chemical that is applied to weeds after the weeds have emerged from the soil) which kill weeds that are actively growing. Postemergence herbicides do not prevent weeds from germinating.

The best time of the year to control perennial weeds is in late summer or early fall when the weeds are preparing for winter. In preparation for winter, perennial weeds move energy reserves from the leaves to underground stems and roots, so a herbicide application at this time will ensure movement of the herbicide to these plant parts, thus resulting in a more effective kill because the roots are being affected. Spring applications to perennial weeds can slow their growth and may kill them, but it is more difficult. Regardless of when applications are made, make sure the weeds are actively growing at time of application. Avoid mowing for 1 to 2 days before and after the application to ensure maximum uptake of the herbicide by the weeds.

There are many broadleaf weed control products available for home use. These products will contain one or a combination of the following chemicals: 2,4-D, 2,4-DP, MCPP, MCPA and dicamba. They are safe to use on cool-season lawn grasses. Liquid and granular formulations of these chemicals are available. It is very important to properly calibrate sprayers or granular spreaders to ensure accurate, uniform application and avoid spraying adjacent flower beds or susceptible plants. Be sure to read and follow all label directions.

Perennial grassy weeds

Perennial grassy weeds are the most difficult weeds to control in a home lawn. Some common perennial grassy weeds include quackgrass, roughstalk bluegrass, smooth bromegrass, annual bluegrass (there are some perennial biotypes) and even other cool-season grasses such as tall fescue and creeping bentgrass. There are essentially no herbicides available for the selective control of these weeds in a lawn. Removal of these problem weedy grasses prior to establishing a lawn and the use of high-quality seed or sod is essential to preventing these weeds from becoming a problem. Many home lawns are established with poor quality seed that has high amounts of weeds such as annual bluegrass and roughstalk bluegrass. What is contained in a seed lot you are considering purchasing is readily available on the seed label, but most homeowners are unaware of its importance. If small patches of perennial grasses are found in a lawn, physical removal with a shovel or spraying with a non-selective herbicide such as glyphosate is the only option followed by re-seeding or sodding the bare areas.

Annual grassy weeds

Weeds like crabgrass and foxtail are warm-season grasses that germinate from seed in the spring and infest lawns during the hot days of summer. They tend to invade lawns along sidewalks and driveways where temperatures are hottest and lawns are thin. Thick, vigorously growing lawns will out-compete most annual grassy weeds.

Annual grassy weeds are best controlled with pre-emergence herbicides (a chemical that is applied before the seeds have germinated) which kill germinating weeds. These herbicides must be applied well before the weeds germinate since they will not kill weeds once they have emerged. Additionally, some of these pre-emergence herbicides are impregnated on fertilizer granules and applied as a weed and feed. Crabgrass will germinate when soil temperatures reach 55 to 60ºF. This occurs around mid-March to early April for the Treasure Valley, Magic Valley and northern Idaho and late March to mid-April for central and eastern Idaho.

There are some herbicides that will kill young annual grassy weeds, but they usually only work well on very young plants, so application timing is critical.

Do not overseed into areas that have recently been treated with pre-emergence herbicides because the chemical will kill emerging lawn grasses as well. Check the label of the herbicide to see how long you need to wait before planting in an area treated with a pre-emergence herbicide.

Thatch is a layer of dead organic matter below the green growing part of the grass and above the soil. In excess, it can form a dense, brown spongy layer that impedes water and nutrient movement into the soil. Thatch accumulation on lawns is a natural process that occurs as stems and roots die and are slowly broken down by soil organisms. Small layers of thatch less than one-half inch are acceptable. When managed properly, lawns may not accumulate excessive amounts of thatch. The problem comes when certain management practices, especially fertilization, are done incorrectly, causing an increase in organic matter production. Some management practices, such as irrigation, if mismanaged can negatively influence the soil environment where the organisms that break down thatch live. Differences in growth habits among grass species also affect the rate of thatch accumulation. Spreading type grasses like Kentucky bluegrass are more prone to thatch accumulation because of their vigorous rhizomes, whereas bunch-type grass like perennial ryegrass and tall fescue are not as prone to thatch accumulation.

Contrary to popular belief, grass clippings do not contribute to thatch accumulation and should be returned to the lawn. See the bulletin, Don’t Bag It! Recycle your grass clippings, CIS1016 (pdf) for more information on what to do with lawn grass clippings.

Excessive thatch (more than one-half inch) is detrimental to the health of a lawn for many reasons. Thatch has poor water holding capacity, does not buffer temperatures well, and impedes water and nutrients from entering the soil. A thick thatch layer soon becomes the growing medium for roots and growing points of the grass instead of the soil. When this happens, grass is much more prone to heat and drought stress as well as more susceptible to disease and insect damage.

Thatch prevention

Following proper guidelines for mowing, fertilization and irrigation will help keep thatch accumulation to a minimum. Mow at the proper mowing heights and follow the 1/3 rule to keep the grass from becoming stressed. Fertilization to avoid excessive growth also is important in preventing thatch buildup. Never apply more than 1 lb of nitrogen per 1000 ft² at any one time, especially in the spring when the grass is growing vigorously. Irrigating to encourage deep rooting will also keep thatch to a minimum. Remember to water "deep and infrequent’ for best results.

Thatch removal/management

Power raking is commonly used to remove excessive layers of thatch but do so with caution. Deep power raking can cause excessive damage to a lawn and even remove large amounts of living grass. Frequent, shallow power raking may be more beneficial.

Core cultivation/aeration is the preferred method for managing thatch. Aeration involves using a machine with hollow tines that penetrate the lawn and remove soil cores. The benefits of core cultivation include relief of compaction, improved air movement into the soil, improved water infiltration, and improved root growth. Additionally, the soil cores, if left on the surface, will mix with and help break down thatch. Make sure the ground is moist before aerating to ensure maximum depth penetration of the tines. Dragging the cores with a piece of chain-link fence helps break and mix them into the lawn. Soil cores can also be broken up with a rotary mower. Over time and with irrigation, the cores will wash into the lawn.

When to aerate and how often? Most home lawns should be core cultivated at least once each year. The best time of the year is either in the fall or the spring when soil temperatures are ideal for root growth. Fall is the preferred time since the aerification holes will not be exposed to excessively hot temperatures during the summer and any weed seeds that were exposed with the soil cores are less likely to compete with the grass. Do not core cultivate during the summer due to excessive heat and drying.

University of Idaho publication, Thatch prevention and control in home lawns, CIS 1063, contains additional information and can be downloaded in PDF format.

Most homeowners enjoy working on their yards, but sometimes professional help is needed for certain operations such as insect control, irrigation installation, etc. If you are unprepared to conduct these types of operations yourself, a lawn care company provides a viable option.

The degree of service offered varies among companies, with some offering only fertilizer and pest control applications and others offering complete lawn maintenance. Even with complete lawn maintenance services, the homeowner will still be expected to properly water and mow their lawn. If irrigation or mowing practices are not properly performed, even the best fertilizer and pest management applications will not result in a healthy lawn.

Take time to fully understand what the lawn service company will be providing and understand what results to expect. Be realistic in your expectations and understand that sometimes overriding factors such as extremely poor soil or unusual weather conditions can negatively impact even the best planned maintenance program.

Lawn care companies vary in the type of service they provide and the degree of professionalism and expertise of the employees. When choosing a lawn-care company, consider the flexibility of the programs offered. Will they skip a spring fertilization in place of a fall application? Will they skip a spring crabgrass control application and apply a post application if needed? The response time of the company also is important. How quickly can a technician be on site to evaluate your lawn?

The level of expertise is perhaps most important. Responsible lawn-care companies will be members of state and national lawn-care associations and will have employees that are certified landscape technicians (CLT). Certification is a national hands-on testing program administered by U.S. state landscape/nursery associations that seek to recognize proficiency in the landscape profession and provide the public with a means of identifying qualified landscape professionals. You should hire companies that have CLTs on staff because they have demonstrated their professionalism in the industry and have validated their landscape skills. Ask lawn care companies if they have CLTs on staff or if they are members of the Environmental Care Association of Idaho (ECA of Idaho), Professional Lawncare Association of America, or Associated Landscape Contractors of America. If they are, this tells you the company takes its profession seriously and participates in educational activities to remain abreast of the latest technology and information. A list of companies that are members of ECA of Idaho can be found at the following website: www.ecaofidaho.org/search/ProfessionalSearch.cfm.