Gardening is one of life’s basic pleasures. Idahoans face some of the nation’s most daunting growing conditions, including our high-pH soil, lack of water, cold winters and hot summers. Learn how to successfully grow healthy plants, organically or conventionally. Know your soil, water and nutrient needs, how to divide and protect your plants, add organic material to the soil and help your plants thrive.
Gardening enriches life, adds beauty to our homes, brings a sense of satisfaction and accomplishment, provides a healthy form of leisure and relaxation, and/or puts the unequaled quality of home-grown produce on our table. Gardening may be simple and accomplished in limited spare time, or it can be treated as an all-consuming hobby. Regardless of the objectives and emphasis, understanding basic concepts of plant culture and care increases chances for success and brings pleasure to the gardening experience. This website is designed for the aspiring Idaho gardener and includes both basic and advanced gardening principles. It provides links by subject to sites with comprehensive garden information. It is a one-stop shop for those who wish to approach gardening from an educated perspective.
Tools are essential for establishing and caring for a garden. They are necessary for soil preparation, planting, cultivation, manicuring plants, irrigation, applications of fertilizers and pesticides, and in some cases harvesting. The type of equipment needed depends on a number of factors, including the garden size, physical abilities of the gardener, time dedicated to gardening and budget.
There are many tools, both hand-operated and power-driven, available to assist both novice and seasoned gardeners. The most commonly used tools include hoes, shovels, trowels, all of which come in several forms for different applications. There are also spading forks, tillers, shredders, pruning shears, loppers, tillers and other specialized tools. Once you have a little gardening experience you will be better able to decide which tools fit your personal tastes, situation and objectives.
The Idaho Master Gardener Handbook, chapter 6 (PDF) discusses tool selection and care with illustrations.
Dr. Leonard Perry, University of Vermont, describes his preferences when using garden hand tools.
Most plants’ nutritional needs are supplied by the soil. Therefore, proper soil preparation will go a long way toward achieving a successful garden.
The ideal garden soil is deep, friable, well-drained and high in organic matter. Soil preparation provides the basis for good seed germination and growth of plants. Managing soils for optimal plant growth is an ongoing process that consists of proper tillage, adding amendments, and proper fertilization and irrigation.
Regional and textural variation
Soils in Idaho vary widely due to topography, climate, and origin. In southern Idaho, most soils have a high pH (alkaline) and contain very little organic matter. These soils may need extra applications of phosphorus and micronutrient fertilizers and should never be amended with lime or wood ash.
Northern Idaho soils can have a relatively low pH (acidic) and contain plenty of organic matter. Some of these soils may need the pH adjusted upward with lime.
In either location, soils can vary in texture from sand to clay. Sandy soils need constant addition of organic matter, frequent and light applications of water, and constant fertilization. Clay soils may need to be amended with organic matter and/or soil amendments to improve water penetration. It is important to know the characteristics of your soil in order to design an appropriate management plan.
No matter the soil type, careful use of various amendments can improve soil and provide the best possible starting situation for your plants. The best amendments provide organic matter: manures, composts, peat moss, crop residues, grass clippings, green manures, bark, wood chips, straw, or any number of other materials. Choose the type of amendment according to availability and cost.
Before fertilizing or tilling, it is best to get the soil tested for nutrients, pH and organic matter. Several labs, both university and private, will test your soil for a fee. (Contact your UI Extension county office for a recommendation.) Once you determine fertilizer needs, broadcast fertilizer evenly on the soil surface and till it in. Make sure the soil is not too wet during cultivation to avoid compaction.
Master Gardener Handbook- Soils and Fertilization.
Historical. For more information on soil preparation, see the brief, but excellent Utah State University publication, Preparing Garden Soil.
Historical. Washington State University provided a comprehensive guide to soil management.
Composting is a natural biological process that degrades a diverse mixture of ingredients such as leaves, grass, plant material, etc. into a soil-like material called compost. These degraded organic materials (compost) can then be recycled by applying it to the soil. Composting is a good way to use household and yard waste to improve garden soil. Composting naturally happens, but we can help speed the process by utilizing techniques that enhance the microbe’s (bacteria and fungi) ability to do their job.
Composting can be pursued at many levels, from a gardener who likes to produce “black gold” to the operation of a multi-acre commercial composting facility. Gardeners who compost their own landscaping and food scraps can follow a few simple guidelines. You do not need to worry about complex formulas, chemical equations or studying microorganisms.
Methods of composting
The most common way to compost is to collect organic matter in open piles or place the material into bins or barrels. It is important to use only appropriate organic materials in the compost pile, which includes almost any garden or table waste that is plant-derived. Exceptions are plant materials that may harbor disease, noxious weed seeds, or material that has been treated with a persistent herbicide. Materials derived from oily foods or animal products should not be included in a compost pile.
A compost pile is created by layering green plant materials, brown and woody plant materials, and garden soil. Once a pile is constructed, composting success depends on providing microbes with the conditions they need to grow and thrive, which are oxygen, moisture and nutrients. These needs are met by turning (mixing) the pile weekly, occasionally adding water to the pile to maintain good moisture, and adding a small amount of fertilizer that is high in nitrogen. Good compost can be created in as little as six weeks with proper temperature and ideal conditions. With less ideal conditions, it may take much longer.
An optional way to compost is using worms (sometimes called vermicomposting). This technique works for composting inside the home. It is useful for those who live in apartments or lack space for the more common ways of composting.
For a thorough discussion of composting principles, read University of Idaho bulletin Composting at Home or the composting section of the University of Idaho Master Gardener’s Handbook (PDF).
Historical. See the Penn State site for a simplified version of how do home composting.
Learn how to compost using worms from Washington State University, Whatcom County.
Fertilizing gardens and landscapes is important to maintain healthy growth and acceptable appearance. Under natural forest conditions, dead leaves, needles and twigs break down to provide a fresh resource of minerals for plants to use. Landscapes usually do not have this nutrient source, since landscape debris is routinely hauled away, so landscapes need extra minerals.
Many products are available to fertilize your plants. Understanding basic plant nutrition and fertilizer application principles will help you choose a good fertilizer for your needs.
Sixteen chemical elements are known to be important to a plant’s growth and survival. Plants get three of these, carbon (C), hydrogen (H) and oxygen (O), from air and water. The other 13 mineral nutrients are acquired by plant roots, which absorb soil minerals dissolved in water. These 13 required mineral nutrients are divided into two groups: macronutrients and micronutrients.
The primary macronutrients are nitrogen (N), phosphorus (P) and potassium (K). Soils usually run out of primary macronutrients first because plants use large amounts for growth and survival. Most gardens will need some of these three nutrients added each year.
The secondary macronutrients are calcium (Ca), magnesium (Mg), and sulfur (S). Fertilizing with these nutrients is not always needed.
Micronutrients are needed in only very small quantities. The micronutrients are boron (B), copper (Cu), iron (Fe), chloride (Cl), manganese (Mn), molybdenum (Mo) and zinc (Zn). The high pH soils of southern Idaho often do not have enough S, Fe, Zn and Mn.
Picking the right fertilizers
Calculating fertilizer application amounts can be a daunting task for the new gardener. Before fertilizing, determine how much of which nutrient(s) are needed. Use the historical recommendations found in many garden publications or the results of a soil test. The most reliable way is a soil test. Your county Extension educator can provide instructions for taking a soil sample and ordering the test.
Next, look at the nutrient content or grade of the fertilizers. This information is found on a fertilizer package in the form of three numbers. For example, if the fertilizer grade is listed as 10-10-5, the fertilizer contains 10% nitrogen (first number), 10 percent phosphorus (second number), and 5% potassium. If there is a fourth number, it is the percentage of sulfur. The numbers on a fertilizer package are always in the same order, nitrogen-phosphorus-potassium.
The final piece of information that is needed is the land area to be fertilized. Once all of these factors are known, refer to the bulletin Using Soil Tests Results for Garden Fertilization to figure out how much fertilizer to apply. For information about fertilizing vegetables, refer to the Soil Preparation for Garden Vegetable section in this web site.
Organic materials can take the place of inorganic fertilizers in the garden. Common forms include blood meal, bone meal, cottonseed meal, sewage sludge, composts and manures. These fertilizers are usually relatively low in nutrient content compared with conventional formulations and sometimes relatively large quantities need to be applied. Especially when purchased pre-packaged, organic materials can be more expensive than inorganic fertilizers. Colorado State University has published a great discussion on organic fertilizers (PDF).
Fertilizing in a landscape is complicated by the fact that different plants have different nutrient requirements. For instance, a lawn uses high amounts of nitrogen while trees generally need very little nitrogen, especially in late summer and fall when fertilizing may spur new growth, which may result in winter cold injury. Managing fertility on other types of plants in Idaho is described in these University of Idaho online publications:
- Historical. Fertilizing Landscape Trees
- Growing Raspberries and Blackberries
- Growing Blueberries (northern Idaho)
- Growing Strawberries
- Historical. Backyard Grapes
- Northern Idaho Lawns
- Southern Idaho Lawns
- Beans and Peas
- Potato Production in the Home Garden
You can download or buy production and fertilization guides for many additional garden plants from the gardening section of the University of Idaho Extension publications catalog.
Keep in mind that adding materials to the soil may be beneficial in certain geographical areas while detrimental in others. For example, wood ashes and lime make acidic soils more alkaline (higher pH). These may be good amendments for northern Idaho’s soils, but not for southern Idaho’s calcareous, alkaline (high in lime) soils.
There are other excellent fertilizer guides online. These include:
- A general discussion about fertilizing a home garden is found in the bulletin Fertilizing Gardens published by University of Idaho.
- Fertilizing Your Garden, a good publication by Oregon State University, provides information on interpreting soil test results, determining fertilizer needs and calculating application amounts.
Pesticides are an effective tool for combating numerous problems encountered in the home landscape and garden. When used properly they can save time and labor. Used improperly, however, pesticides can cause damage to plants, people and the environment. It is very important to read and understand the label on any pesticide container. In fact, the label is the law. Keep in mind that all pesticides are potentially poisonous and that improper application or use can be dangerous.
There are several categories of pesticides, and numerous products, available for use in the home garden.
Herbicides can be used to control weeds. In a garden, herbicides can make weed management easier, but cannot completely replace hand weeding.
Some products kill all plants and should be used only where there are no plants you want to keep.
A few of these products sterilize the soil and prevent growth of any plants for several years. Products that sterilize the soil may also damage nearby trees and shrubs if the roots grow into or are already located in the treated area. Be sure you understand the nature and limitations of any compound applied.
Some herbicides can kill seeds as they germinate but do not affect growing plants that are already growing. These can be used to control weeds around shrubs, trees or emerged garden plants.
Other herbicides kill only certain types of plants, such as grasses. These can be used to control grass weeds in broadleaf garden plots, or their opposite counterparts can be used to control broadleaf weeds, such as dandelion, in lawns.
Insecticides are intended to kill destructive insects and are often very important for managing garden pests. However, because these compounds are designed to kill animal pests, they are often the most toxic and damaging to the environment of all classes of pesticides. Insecticides can also kill beneficial insects so it is again important to read the label to avoid killing insects that help you out in the war against damaging insects. Insecticides should be used only when needed and then only when using all appropriate precautions.
Fungicides and bactericides are used to control plant diseases and can save your lawn, garden and landscape plants from disease when applied in a timely manner. For many diseases, fungicides must be applied to the target plants before the disease appears. Consequently, they are often used for prevention.
For detailed general information on controlling pests in gardens, see chapters 9 – 14 in the Idaho Master Gardener’s Handbook.
Historical. For general instruction on reading labels and using pesticides in the home garden, see the following informative University of Idaho publication: Pesticides for the Home Garden and How to Use Them
See the EPA document Citizen’s Guide to Pest Control and Pesticide Safety for a comprehensive treatment of pesticide selection, management and safety.
View a comprehensive database of pesticide products for home use from the Household Products site.
Purdue University has published A Strategy for Pest Control in Home Gardens outlining non-pesticide strategies for pest control.
Historical. For information on storing and disposing of pesticides, follow this link to an informative University of Idaho publication, Idaho Homeowner’s Commonsense Guide to Pesticides.
The United States Department of Agriculture defines organic as “an ecological production management system that promotes and enhances biodiversity, biological cycles and soil biological activity. It is based on minimal use of off-farm inputs and on management practices that restore, maintain and enhance ecological harmony.
Organic vegetable gardening promotes and enhances natural diversity and biological cycles. Rather than relying on synthetic fertilizers and pesticides, organic gardening is based on making the garden self-sufficient and sustainable. You can ease your gardening practices into the organic arena by starting with some of the easier aspects of organic gardening, such as mechanical control of weeds and insect pests.
The growing and selling of produce and products labeled “Certified Organic” is strictly monitored by the United States Department of Agriculture involving a rigorous certification process and compliance with federally mandated regulations for exclusion of non-approved crop management materials, such as synthetic pesticides and fertilizers.
Many home gardeners would like to reduce synthetic chemical use around their children, pets and environment. While they won’t need to certify their backyards, home gardeners may adopt some of the recommended practices to grow flowers, vegetables, fruits and even lawns by using biological and cultural controls, composts and organic fertilizers along with conventional methods. Some gardeners may choose to completely exclude the use of inorganic fertilizers or growth regulators to reduce dependence on non-renewable resources. Whatever the desire and intent, there are some universally applicable concepts that will help the organic gardener succeed.
Soils, pests and diseases
The first step in this transitioning a garden to organic is improving and maintaining soil fertility and quality. Healthy, fertile soils are basic to successful organic vegetable and fruit production. Management and addition of organic matter, in the form of composts, manures, green manures and plant residues, is the most important principle to understand for maintaining soil productiveness in an organic system. Organic matter in various forms should be added to the soil annually. There are also many organic fertilizers that can be used to supplement plant nutrition, especially to meet the need for nitrogen and phosphorus. Utah State University has published an excellent organic fertilizer guide, Selecting and Using Organic Fertilizers.
Pest management is the most challenging aspect of organic gardening. Weeds can be controlled with cultivation, pulling, or smothering using mulches. Insects must be closely monitored and controlled using various mechanical methods, predator insects, baits and traps, mild soaps or directed water streams. There are several organically certified insecticides that are useful in the control of insect pests, including Bacillus thuringenisis, insecticidal soaps, rotenone, or natural pyrethrins.
Diseases are best managed through the use of resistant varieties. It is also important to purchase and plant disease-free seed to avoid introducing disease pests into the garden as well as remove and discard diseased plants, rotate annual crops to different places in the garden each year, and keep the garden area free of weeds and dead plant material that may harbor disease organisms. Some leaf-infecting fungi can be controlled using organic fungicides.
A comprehensive list of approved organic materials can be found on the Organic Materials Review Institute web site.
Organic gardening can be simple or complex, depending on the desires of the gardener. There is plenty of good information available on the topic from numerous authoritative sources. Here are some of the best:
View a simple introduction to organic gardening concepts from Mississippi State University
For information on a straightforward, but more detailed approach to organic vegetable gardening, visit this list of University of Florida publications.
Historical. For an in-depth discussion of organic soil management principles, read Producing Garden Vegetables with Organic Soil Amendments from the University of Florida.
If you wish to move beyond a cursory understanding of organic gardening practices, select from a series of publications from the University of California, Davis describing detailed organic production principles.
History of organic gardening
The term “organic farming” was first used in England in the early 1940s, emerging from the biodynamic movement in which a farm was perceived spiritually as a dynamic, living “whole organism.” The concept was brought to the United States in the mid 1940s and widely promoted by J.I. Rodale, founder of Organic Farming and Gardening Magazine (now Organic Gardening) and author of Pay Dirt: Farming and Gardening with Composts and How to Grow Fruits and Vegetables by the Organic Method. Rodale strongly believed in the relationship between living soil and healthy food was achieved by returning animal manures and plant debris to the system by way of composts.
On the surface, watering home landscape or garden plants appears to be simple and straightforward. However, it is complicated by a number of factors including climate, available water source, weather, topography, soil type and the irrigation system available. As a result, irrigation is poorly accomplished by most homeowners. In fact, many homeowners fall prey to over-watering, wasting money and natural resources. Irrigation has a greater impact on plant health in Idaho landscapes than any other input, so doing it properly is critical.
Many landscape trees are lost each year because the root zone was not adequately watered in the late fall, and young trees are often damaged or killed by over-watering. Water-stressed plants are subject to increased insect and disease problems and decreased winter hardiness. Excess watering leaches out nutrients and pesticides that can pollute ground water. As you can see, it is very important to understand how to apply the proper amount of water. Important decisions associated with proper irrigation include choice of equipment, determination of irrigation frequency, and knowing how much to apply.
There are several types of irrigation systems, each with advantages and drawbacks. Most homeowners use some type of sprinkler application, some manually controlled and others automated, while some flood irrigate. Drip irrigation is becoming popular as it can conserve large amounts of water, as well as aid in weed control. Whatever the method, it is important to know the application rate of the system and the application is uniform. To properly irrigate, the root zone should be completely filled with water, and then allowed to partially dry between irrigations so to ensure adequate oxygen for the roots. The root zone for lawns is about 10 to 12 inches, vegetable gardens 18 inches, shrub beds up to 2 feet, and trees approximately 3 feet.
Three important pieces of information are needed to properly irrigate: 1) the application rate of the system, 2) the amount of water plants are using, and 3) the amount of water required to fill the root zone. The University of Idaho has published a detailed and valuable document on using this information to determine best irrigation practices, Watering Home Lawns and Landscapes.
Soil type (texture) has a large impact on irrigation practices. Sandy soils may hold enough water for only a single day of plant growth. Fine-textured such as silt or clay soils may hold enough for 5 or 6 days. Consequently, it is important to adjust watering practices based on soil texture. In principle, sandy soils will need a very light application of water on a very frequent basis. Heavier soils will need water less often, but will need a larger amount at each irrigation event. Soil texture does not change the amount of water plants need or use, but it does change the schedule (frequency) for supplying the water.
One of the problems of irrigating landscapes and gardens is that multiple plant species, each with their own water requirements and rooting depths, are grouped together. For most plants in a mixed garden or landscape, it is adequate to water to a depth of about 1 foot. However, if trees or shrubs are part of the landscape, for every third or fourth irrigation, the sprinkler system should operate long enough to fill the root zone with water to a depth of 2 to 3 feet. After filling the root zone to a 2- to 3-foot depth, the interval to the next irrigation should not change. On the next irrigation, run the irrigation system just long enough to fill the root zone to 12 inches.
In areas with limited water supplies, there are ways to conserve. One is to select plants that need limited amounts of water. Many of our Idaho native plants are adapted to dry summer conditions. Another way to conserve moisture is to use mulch in flower beds and around trees to limit evaporation from the soil surface.
Find additional help with calculating water needs for lawns and trees at University of Idaho Extension. For an in depth discussion on calculating amount of water to apply to a lawn, see University of Idaho bulletin Watering Home Lawns: How Much and How Often.
For a general discussion of home landscape water management, see the Montana State University publication Yard and Garden Water Management.
The University of Georgia supplies an outstanding discussion of irrigation systems in the bulletin, Irrigation for Lawns and Gardens. For a listing of water conserving plants adapted to Idaho, see Washington State University bulletin Hardy Plants for Waterwise Landscapes.