Start planning your vegetable garden by answering these simple questions.
How much time do I have to dedicate toward vegetable gardening?
If you can dedicate only a few minutes a day, plan a small garden that contains two or three of your favorite vegetables. Alternately, if gardening is a life-sustaining activity, the scale of production may be quite large and your plans should be based on food storage potential.
What do I like to eat?
Make plans to produce only crops that you and your family like and will take the effort to prepare and consume.
How much room do I have to dedicate to a vegetable garden?
If space is limiting, plant only the crops that produce large quantities in a small area, such as tomatoes or cucumbers.
Where should I locate my garden?
Ideally, you will want to select a spot in the yard that receives full sunlight, is within a warm microclimate (next to a south-facing fence or wall), is not frost prone (low swale), is away from prevailing wind patterns, is at least 20’ from large trees and shrubs, is conveniently close to your house, and has access to a good source of irrigation water.
What type of vegetable production system should I use?
If you want to produce vegetables on a large scale, you might want to use the traditional victory garden design (straight, wide rows). If space is limited it will be better to use raised beds (intensively managed blocks) or containers (pot production on a porch or patio).
What recurring annual planning activities are necessary?
There is also a little planning that must be done every year in order to maximize crop yield and quality.
Choose the best vegetable varieties
In the short-season climates typical of much of Idaho, choosing the right varieties is a critical key to success. Information about the best varieties can be obtained from experienced gardeners, Master Gardener volunteers, local nurserymen, and county educators.
Place and rotate the crops
Crop rotation, the practice of changing the location of crops to avoid disease and nutritional problems, is essential to maintaining plant health. It is also necessary to place crops where they can compete with surrounding vegetation.
To learn more, download and read this University of Idaho publication: Planning an Idaho Vegetable Garden.
Vegetable gardening systems fall into three major categories, 1) low-intensity victory gardens planted in wide rows or hills, 2) intensive gardening systems planted in beds, or 3) container gardens.
Victory Garden Designs
The victory garden is especially good for growing plants that are needed in large quantities, such as corn, peas, beans, potatoes, and broccoli. There are many adaptations to the single row planting design typical of the victory garden. Here are descriptions and pointers on managing common planting arrangements:
Row Planting: This arrangement consists of long, straight rows, usually two or more feet apart, with a single line of plants growing down each row.
Broadcast Row Planting: Broadcast planting usually involves placing seed in rows arranged as wide bands rather than single-width rows. Many crops, especially root crops such as carrots, radishes, and beets will produce higher quality vegetables when planted this way
Hill Planting: Larger vegetables, such as melons, squash, corn, and cucumbers, may be planted in hills. The hills can be arranged as extra wide rows to facilitate cultivation with distance between hills based on recommendations for individual crops.
Intensive Garden Designs
Intensive garden designs require considerable effort to plan and install, but are thereafter relatively easy to maintain. Proven intensive garden designs include raised beds and vertical gardens. When combined with production techniques that include interplanting, succession planting, relay planting, and edible landscaping, these garden designs will help maximize the use of limited space.
Raised Beds: The typical design of the “raised bed” garden includes a defined border filled with heavily amended soil to a level above the surrounding ground. Typical beds are raised six to eight inches but they may be as much as three feet above grade. Borders may be made from concrete, masonry, or wood. Wood landscape timbers are commonly used for borders and should be made of redwood or cedar to minimize deterioration due to constant exposure to moisture. Although there is no evidence that the new generation of treated timbers is toxic or harmful to plants or consumers, it may be wise to exercise caution and use only untreated wood.
Soil preparation is an important aspect of raised beds. The final soil mix commonly consists of one part native soil and one part compost or aged organic matter. Many other choices for soil components exist and include manures, peat, sand, vermiculite, or perlite added in various quantities. The simplest method for preparing the soil is to remove the top 12 inches of soil from the completed bed, place it in a pile, mix the pile with an equal amount of organic matter, and shovel it back into the bed
Plant arrangement within a raised bed should optimize the use of the limited space. The goal is to space plants equidistant from each other on all sides, so that, at maturity, plant leaves touch or slightly overlap.. The use of dwarf or bush type varieties will help minimize space needed for producing many crops, such as beans, cucumbers, tomatoes, and squash.
To learn more about gardening in raised beds, see the Colorado State University publication: Block Style Layout in Raised Bed Vegetable Gardens.
Vertical Gardening: The use of trellises, nets, strings, cages, or poles to hold plants upright and limit horizontal spread constitutes vertical gardening. Vining and sprawling plants, such as cucumbers, tomatoes, melons, and pole beans, are obvious candidates for this type of gardening.
Structures for supporting plants can take advantage of existing structures, such as buildings or fences, or can stand as an isolated structure. The height of the support apparatus will depend on the crop being grown. Shorter plants such as tomatoes, cucumbers, and pole beans will grow to a height five to six feet. Squash may need fifteen to twenty feet of vertical space or a structure that will allow some horizontal growth at the top such as a high tunnel
Vertical gardening saves considerable space but is labor-intensive. This is mostly due to the need for staking, tying, and pruning associated with the process of training new growth upward.
A window sill, patio, balcony, or doorstep can provide sufficient space for a productive container garden. Gardening in containers requires more attention to detail than any other gardening method. The plants have only a small amount soil available for root growth, meaning limited water and nutrient availability. Also, the plants are subject to heat and other stresses. As a result, care requirements are more stringent and often unique in comparison with a traditional garden.
Choosing Containers: Containers can be made of clay, wood, plastic, or metal. Most importantly, they should be the proper size and provide good drainage.
Selecting the proper container size is a balance between supplying adequate soil volume and making sure they can be moved in cases of inclement weather or for winter storage. Choose the largest containers you can feasibly manage. Container depth is important because most plants need at least 6 to 8 inches of soil for proper rooting.
Choosing Soil Media: The best soil media for container gardens are ironically are called ‘soilless mixes”. These contain combinations of peat moss, perlite, and sand. Some include wood chips or bark. Native garden soil alone does not make good potting soil because it does not provide adequate drainage or air exchange. Soilless mixes are sterile and contain few nutrients. Manufacturers usually add major plant nutrients to mixes they sell, but may not add trace elements that are necessary for good plant growth. This problem can be solved by using the soilless mix as a base and adding compost (about 25% by volume).
Placing the Containers: Position containers where plants will receive sun during the entirety of daytime hours. If this is not possible, choose crops that can withstand some shade. Generally leaf crops can tolerate some shade while vegetables grown for their roots or fruits need a minimum of 8 to 10 hours of full, direct sunlight each day. Available light can be concentrated somewhat by providing reflective materials around the plants (e.g., aluminum foil, white-painted surfaces, marble chips on the soil surface).
Choosing Vegetable Crops and Varieties for Containers: The best container crops are those that allow best use of the available space. This includes many herbs, carrots, radishes and lettuce, or crops that bear fruits over a period of time such as tomatoes, peppers, or cucumbers. Dwarf or miniature varieties of many crops are available.
Tips for Growing Vegetables in Containers: If you can move or protect your container garden from frost, plant two to three weeks earlier than you would an outside garden. Avoid planting too many plants in one container. If cages, stakes, or other supports are needed, install them just after planting or thinning to avoid root damage later.
Vegetables suitable for container gardening,
recommended pot size, and spacing between plants
|Vegetable||Minimum container size||Spacing (in) between plants in containers*|
|Bean||2 gallon||2 to 3|
|Beet||1/2 gallon||2 to 3|
|Cabbage||5 gallon||1 plant|
|Carrot||1 gallon||2 to 3|
|Cucumber||5 gallon||1 plant|
|Eggplant||5 gallon||1 plant|
|Kale||5 gallon||10 to 15|
|Lettuce||1/2 gallon||4 to 6|
|Mustard greens||1/2 gallon||4 to 5|
|Onion||1/2 gallon||2 to 3|
|Pepper||2 gallon||8 to 12|
|Spinach||1 gallon||4 to 6|
|Squash||5 gallon||1 plant|
|Swiss chard||1/2 gallon||4 to 6|
|Tomato||5 gallon||1 plant|
|Turnip||3 gallon||2 to 3|
*Any vegetables that produce large plants should have only one plant per container.
Water only when the plants and soil indicate a need. Check containers at least once a day to determine if the soil is damp (but not sopping wet) below a depth of about one inch and water if the soil feels dry.
There are some tricks to conserve water in containers:
- grouping containers together provides shades for the pots and slows evaporation;
- placing something impermeable, such as a plastic or rubber mat, under a pot prevents moisture from moving out of the pot and into cement or masonry surfaces;
- mulching and windbreaks can also help reduce water requirements for containers.
If plants are grown for longer than 8-10 weeks, add water-soluble fertilizer every 2 to 3 weeks. Use dry fertilizer (slow release), well-aged manure, or compost at the recommended rate (information provided on the product label).Inspect plants periodically for the presence of foliage-feeding and fruit-feeding insects as well as the occurrence of diseases. Treat as needed.
To learn more about container gardening, see the following publications:
Proper soil preparation provides the basis for good seed germination and growth of garden crops. The steps of soil preparation include testing, amending, and tilling.
Testing the Soil
Contact your local County Extension Office to get instructions and sample bags for testing your garden soil. Soil tests are especially critical in a new garden plot but soil should be analyzed at least once every 3 years because conditions do not remain static. The soil test will tell you how much organic matter and fertilizer is needed. To get a relibale soil test, you first need to take a proper sample.
Amending with Organic Matter
Organic matter improves soil structure, increases water-holding capacity, improves fertility, and reduces problems with soil diseases. There is no replacement for organic matter in improving soil health and providing good growing conditions for vegetables.
Organic matter can be added in the form of plant waste (such as leaves or lawn clippings), composts, green manures, or aged animal manures. It is necessary to consistently add organic matter (every year or two) because it rapidly breaks down in the soil.
Using compost is a preferred method of adding organic matter to the soil. Apply organic matter to the garden area by spreading a layer of compost 3 to 6 inches deep on the soil surface and tilling to a depth of 10 to 12 inches, if possible with available equipment.
Another method of adding organic matter to soil is to use green manures, which are any living plant material that is mixed with the soil while still green. Green manure crops include such crops as, for example, wheat, oats, clover, mustard and vetch. Grow the green manure in the part of the garden where you will later chop it while it is still green and immediately till into the soil.
Animal manures are best applied in the fall so they have time to completely decompose and salts can partially leach out of the root zone before spring planting. It is best to use animal manures that have been aged for one or two years before applying to a garden, or used composted manure.
To make your own compost, see Composting at Home for a detailed discussion of how to do this.
In this brief format, it impossible to provide fertilizer application recommendations that will apply to every gardening situation. But, whether you prefer traditional or organic methods, some concepts are universal. For one, nothing can replace a soil test for providing the information required to make appropriate fertilizer application decisions. Two, for vegetable gardens, additions of nutrients in some form will be required to consistently grow a good crop. Knowing the amount of fertilizer elements required will make it easier to choose an appropriate product to apply.
Generally, for most Idaho soils, a fertilizer that is relatively high in nitrogen and phosphorus, contains a moderate amount of potassium, and possibly some sulfur will work reasonably well. Follow the fertilizer label directions or contact your local County Extension Office about application rates and methods. Also, UI bulletin, Using Soil Test Results for Garden Fertilization, contains information on interpreting a soil test and how to determine the quantity of fertilizer product to apply.
Fertilizer requirements for vegetable crops vary widely, which complicates fertilizer application decisions. Some crops, such as peas and beets need very little fertilizer. Most long-season crops, such as corn and melons require fairly large amounts (see accompanying table).
|Low nutrient-using crops||High nutrient-using crops|
Deciding how to fertilize a vegetable garden should take into account the fertilizer amounts needed by “low-nutrient using” crops vs. “high nutrient-using” ones. If you are planting a garden for the first time, it is almost essential to have a soil test so you know the nutrient status of the soil to help determine how much, if any, fertilizer to apply.
If you have been growing a garden for several years in the same location and have been reasonably satisfied with the production, a soil test may not be essential. However, a yearly application of fertilizer is still likely needed. Using a complete fertilizer product, fertilize your garden with 2 to 3 lb N per 1000 ft2 and immediately till it into the soil at the beginning of the season just prior to planting. This amount should be adequate for the low-nutrient using crops. Then after the plants are up and growing, apply an additional 2 to 3 lb N per 1000 ft2 alongside the row—oftentimes referred to as a “sidedress” application—and water into the soil. For this application, you can use a product that is high in N and low in other nutrients. Use UI bulletin, Using Soil Test Results for Garden Fertilization, to determine actual amounts of fertilizer product to apply depending on the nutrient content of the product purchased.
Sandy garden soils, which do not hold nutrients as well as clay, silt, clay loam, silt loam, and other non-sandy soils, require some modification of the above fertilizer application practices. Only part of the total applied fertilizer should be put down before planting. The rest should be applied in small increments during the growing season. This provides the plants with the required nutrients while reducing losses due to leaching. A soil test will help you determine your soil texture.
The final step in soil preparation is tillage. Ideally, soil should be tilled to a depth of at least 10 inches. This can be very difficult with small garden equipment. If larger equipment cannot be used, it may be beneficial to occasionally fracture the soil to a greater depth by pushing a long-tine garden fork deep into the ground and pulling the handle backward to break up the hard lower layers.
It is important to avoid working soil when it is too wet. This is espcecially true for non-sandy texture soil. Working wet soil breaks down the soil structure causing it to become cloddy and hard. The negative impact of tilling wet soil may last for years. To determine if the soil is dry enough to work (till), take a handful and squeeze it tightly into a ball. If the ball breaks into granular pieces when pressed lightly between your fingers, it is dry enough to work. If the ball remains intact and feels sticky when you squeeze it, wait a few days before scheduling tillage operations.
For more information about soils, soil preparation, and fertilizers, study the Idaho Master Gardener Handbook, Chapter 5: Soils and Fertilizers.
Choosing Vegetable Seed
Choose seed from a reputable seed company. Carefully select varieties that are adapted to local conditions. Proper variety selection can mean the difference between success and failure in the garden. If you are unfamiliar with varieties that grow well in your locale, ask other successful gardeners, local nurserymen, or a county educator.
For more information about vegetable varieties suitable for growing in Idaho, see the UI publication: Choosing and Growing Adapted Vegetable Varieties
For more additional pertinent information, see the Utah State University publication: Home Vegetable Garden Variety Recommendations for Utah
Planting Vegetable Seeds Outdoors
In order to germinate properly, seed must be planted at the right depth and remain moist. As a general rule, vegetable seeds should be covered about three times their lateral diameter (their width, not their length). However, there are exceptions and directions are usually given on the seed envelope. Shallow-planted seed may be covered with clear plastic film (such as plastic food wrap) or wet burlap to raise the soil temperatures and hold the moisture. The covering material should be removed immediately after emergence to prevent burning or abnormal growth of the new plants.
Deciding when to plant seeds can be confusing because optimal planting times vary from crop to crop. The first step in deciding when to plant is to determine the average last frost date for your area. This date can be found in many publications, web sites, or from your local Extension Office. Ed Hume Seeds company maintains a web site with average last frost dates for many locations in Idaho.
Next step is to schedule planting based on the frost-hardiness of each crop. See the accompanying chart for suggestions on planting times of common vegetables.
Once planted, it is imperative that good soil moisture is maintained until the plants begin to emerge. In some years, spring rain and cool weather may make irrigation unnecessary. However, in most years, frequent (up to 2 times a day for the crops seeded shallow and every two or three days for the crops seeded deep), light watering may be required to get the seed off to a good start.
Producing and Establishing Transplants
Transplanting is the process of placing partially grown plants, rather than seed, into the garden. Many vegetable crops benefit from being transplanted rather than direct-seeded into the soil. Transplanting makes weed control simpler, enhances the growth and quality of crops that prefer cool, spring weather (such as broccoli and cauliflower), shortens the time to harvest of many fruit-bearing crops (such as peppers and tomatoes), and allows us to grow many crops that are marginally adapted to short-season climates (such as melons).
Vegetables vary in their response to transplanting. Some are very difficult, others transplant well only if proper precautions are followed, others transplant very easily. See the accompanying table for a listing of vegetables that can be successfully transplanted.
Relative ease of transplanting for common vegetables
|Appropriate for transplanting and easy to handle||Appropriate for transplanting but require extra care for success||Inappropriate for transplanting or do not easily survive the process|
*The vine crops (cucumber, melons, squash, pumpkin) should be transplanted when seedlings are very young (one or two true leaves) and very vigorous. They should be covered and protected from wind and sunburn for about two weeks after transplanting.
**The root crops (beet, carrot, radish, rutabaga, turnip) are easy to transplant but the roots will branch or have other quality problems as a result of root disturbance.
Transplants can be either purchased or grown at home from seed. Growing your own transplants provides some unique advantages such as increasing the availability of unusual varieties, reducing overall cost, and controlling growth so the plants are the right size when you are ready to plant. In spite of the advantages, growing transplants without good greenhouse facilities can be a challenge.
The most important factors for producing healthy transplants are light, soil mix, irrigation, proper size and growth stage, and hardening. During production, more homegrown seedlings are lost to inadequate light than to any other factor. Vegetable seedlings grown under low light conditions are likely to be spindly and weak. They frequently damp-off (a disease that causes young seedlings to tip over and die). If they survive the early growth phase, these plants are often too tender to survive the move outside into the garden. For these reasons, transplants should be grown under conditions that include or mimic full daylight for at least 10 hours each day.
If you do not have a sunny room or back porch with a southern exposure, you will need supplemental lights. Grow-lights are available that supply a good spectrum of light to the plants. The lights should be mounted right over and nearly touching the plants.
It is best to use a soilless planting media containing peat to start seedlings. Soilless mixes are usually free of disease organisms that can cause damping-off. They also hold a large amount of water and maintain the integrity of the rootball when it comes time to transplant. Potting soil can be purchased premixed or you can mix your own soilless media if you prefer; 50 percent vermiculite or perlite and 50 percent fine sphagnum peat (plus a little fertilizer) is excellent for starting seeds.
Timing seed planting to begin transplant production can be a little tricky. Two pieces of information are needed to plan a planting schedule for vegetable transplants. One is the number of days needed to produce an appropriate-sized transplant (see the accompanying table). The other is the date the transplants will be taken to the garden. This can be calculated by knowing the last average frost date for you locale. The cole crops (cabbage, broccoli, cauliflower, kale, brussel sprouts, etc.) and onions can be transplanted 2 to 3 weeks before the last average frost. Most of the salad crops (lettuce, Swiss chard, spinach, etc.) should be transplanted a week or so prior to the last average frost. The tender crops (tomatoes, peppers, eggplants, squash, melons, etc.) should not be transplanted until about one or two weeks after the last average frost and only then if the weather forecast is for reasonably warm and stable conditions. If appropriate protective measures (hot caps, row covers, etc.) are used, the transplant dates can sometimes be earlier by a week or two.
About a week before the transplants are scheduled to go to the garden, they should be “hardened-off”. This is a process of slowly adapting the plants to outside conditions and is necessary for reducing transplant shock and frequency of death. Harden off the plants over a one-week period by moving them outdoors for increasing amounts of time, starting with less than an hour and eventually leaving them outside for much of the day. Move the transplants indoors at night (unless it is forecast to be a warm night) and during inclement weather (especially if it is windy). Water use of the transplants will increase while they are outside, so irrigate accordingly.
Number of weeks required to produce transplants from seed for commonly transplanted vegetable crops
|Crop||Weeks to produce a transplant from seed*|
|Broccoli||5 to 7|
|Brussel sprouts||5 to 7|
|Cabbage||5 to 7|
|Cantaloupe||3 to 4|
|Cauliflower||5 to 7|
|Celery||8 to 10|
|Collard||5 to 7|
|Corn, sweet||3 to 4|
|Cucumber||3 to 4|
|Eggplant||6 to 8|
|Endive||4 to 8|
|Kohlrabi||5 to 7|
|Leek||4 to 6|
|Lettuce||3 to 5|
|Onion||6 to 8|
|Parsley||6 to 8|
|Pepper||6 to 8|
|Pumpkin||3 to 4|
|Squash||3 to 4|
|Tomato||5 to 9|
*The number of weeks needed to produce a transplant is based on growth at near room temperature.
Here are a few additional tips for successfully transplanting vegetables into the garden:
Have garden soil prepared before transplanting. All additives that require time to break down, such as aged manures, sulfur, limestone, rock fertilizers, and green manures, should be incorporated during the prior fall, or at least several weeks before planting.
Transplant on an overcast day, in late afternoon, or in early evening to prevent or reduce wilting. Be sure to water the potted plants thoroughly just prior to transplanting.
Handle plants carefully. Avoid disturbing the roots or bruising the stems.
Dig a hole large enough to hold the roots of the plants. Set vegetable plants only very slightly deeper than previously planted. Tomatoes are an exception. They will develop roots all along the stems, and you can plant deeply enough to leave only two or three sets of leaves exposed. Press soil lightly around the roots of transplants and thoroughly water them in. Pour a cup of liquid starter fertilizer solution around each plant, mixed at about ½ of the concentration recommended on the label.
Protect plants from wind and sun for a few days after transplanting by placing newspaper or cardboard on the south side of the plant, or by covering them with commercially available devices, milk jugs, baskets, or up-side-down flower pots (opaque plastic so the sun can get in).
Water the plants once or twice each day for about one week. Then schedule watering two or three times over the next week before going to a normal irrigation routine. Overwatering can cause transplants to suffer from root rots, so don’t overdo it.
Garden water demands and irrigation scheduling are the result of complex interactions between climate, weather, soil type, plant species, and irrigation practices. This means that there is no one recipe that is suitable for all gardens. Taking the time to learn about proper irrigation in your own situation will pay dividends. There are a few general principles that will help guide your decision on how best to irrigate your vegetable garden.
Once the plants approach full size, typical water use for most vegetables will be ¼ inch (meaning that if you put a can under the sprinkler, the water inside would be ¼ inch deep at the end of the irrigation) per day. This means a summer garden will need around 2 inches of water per week. Because most soils will not hold this much water, plan to irrigate twice each week with the total being about two inches. In the spring when weather is cool and plants are small, they may use less than half this amount of water. In the fall, when plants start to mature, water use will also decline.
Plants use the same amount of water regardless of soil type. However, sandy soils hold less water and plants will use the water very quickly and then become stressed. So, if your soil is sandy, change your irrigation practices to water more frequently but put less water on during each irrigation event.
Sprinkler irrigation is a simple method for making uniform applications of water to the vegetable garden. However, sprinklers wet the leaves and encourage disease development and they also splash dirt on leaves that may add some “grit” to your meals. If these are problems in your garden, consider using a bottom up irrigation method such as soaker hoses or a drip system.
Weeds steal water and nutrients, compete for available light, and reduce the yield and quality of the vegetables. Although weeds will always be present, there are some methods for control that will make them easier to live with.
Hand pulling and digging weeds is probably the best choice for small gardens and raised beds. Hoeing is preferred in larger spaces. Hoeing can damage root systems of larger plants, so push the blade of the hoe only deep enough into the soil to sever weed roots and stay several inches away from the base of the vegetable plants. Manual powered rotary cultivators can supplement the use of a hoe and do a good job on long rows and pathways if the soil is not too wet or dry and if the weeds are not too big.
Cultivation is best done when the soil is somewhat moist, but not wet. The best time to cultivate is two or three days after rain or irrigation. Working wet soil will damage the structure, especially of fine-textured soils, making them compacted and cloddy. On the other hand, when the soil is too dry, weeds are difficult to pull and hoeing is a chore (beyond its usual tedious nature).
A thick layer of organic mulch will prevent most annual weed seeds from germinating and those that do are usually easily pulled. Organic mulches can include straw, grass clippings (make sure they are free of herbicides), bark (small enough to be tilled under at the end of the season), wood chips, or sawdust.
Mulching with black plastic film can also be very effective in reducing weed growth. Using black plastic mulch on the rows and an organic mulch between the rows will nearly eliminate annual weed problems..
Established vegetable plants will shade the soil and prevent the growth of many weed seedlings. The plants are spaced so that the foliage of adjacent plants touches and forms a closed canopy at a mature growth stage.
To learn more about controlling weeds, see the following publications:
Insects should be controlled only when they appear in numbers large enough to be destructive. There are five simple strategies for managing insects in a vegetable garden, effective in either traditional or organic systems.
Be a sanitary gardener. Insects will often overwinter in old garden refuse, so it pays to clean up dead plant material at the end of the year. If you want to keep the organic matter in the soil, till or plow the garden after the last of the crops are harvested.
Maintain good plant health. Healthy plants can often partially defend themselves from pests and will recover from damage quicker.
Physical Control Methods
Use physical barriers and cultural controls. You can keep some types of insects at bay by preventing access to the plants. For example, collars around the lower stems of small plants will foil cutworms.
Biocontrol and IPM
Encourage or release beneficial insects. Encourage the presence of predator insects by allowing the presence of a low level of pest (prey) insects and by avoiding the use of broad-spectrum (kills all insects) insecticides in the garden.
Judiciously use pesticides as a last line of defense. For many insects, both organic and synthetic insecticide options are available. If insecticides are used, direct the application to the specific problem rather than broadcast an application across the garden. Also, use products that target the specific insect you are trying to control. Make an effort to identify and use the most ecologically friendly products available. All insecticides are not equal for either efficacy or impact.
Insects that commonly infest Idaho gardens at damaging levels
- Aphids: These stem and leaf feeders can often be controlled without the use of insecticides. Insecticidal soaps or a hard stream of water that simply knocks them off the plant will usually be sufficient to eliminate damage. Also, aphids will almost always be eliminated by predators if you are patient enough to let them do their work.
- Grubs and Wireworms: These soil-dwellers are difficult to control and may require the use of a soil-applied insecticide prior to planting. This means knowing the history of the garden plot and realizing the problem exists before you see damage.
- Cutworms: This pest often kills seedlings and transplants by chewing through the stems at ground level. Cabbage, broccoli, tomatoes and other soft-stemmed transplants are often the victims. Placing cardboard collars around the base of plants is an effective method to prevent damage.
- Corn Earworm: Control of this pest usually requires the use of an organic or synthetic insecticide product, applied to the green silks once or twice.
- Slugs: In dry climates, slugs and snails are typically not a problem unless too much water is being applied to the garden. If the problem cannot be solved by reducing irrigation, the use of baits and traps can be partially effective.
- Cabbage Worms: These slender green caterpillars chew holes and deposit webs on broccoli, cabbage, cauliflower, and kale. When obvious damage is present, they may require control with bacillus (the organic pesticide sold as Bt) or another insecticide.
- Tomato Hornworms: These large, ferocious-looking caterpillars can defoliate tomato or potato plants within a day or two. Physical control (pick them off the plants and step on them or squeeze them between two rocks) is the best method for eliminating this occasional pest
- Colorado Potato Beetles: These serious pests of potatoes, when present is small numbers, can be removed from the plants by hand. In large numbers they may require an insecticide.
To learn more about controlling vegetable insects, see the following resources:
From Cornell University: Managing Home Garden Vegetable Pests
From Oklahoma State University (very detailed): Home Vegetable Garden Insect Pest Control
From Organic Garden Pests.com (for tips on organic control of insects): Organic Pest Control
Dry climates limit the number of diseases that are common in vegetable gardens but there are a few serious problems that should be monitored.
A number of common virus diseases occur on vegetable crops. These include, but are not limited to, zucchini yellows, cucumber mosaic, potato leafroll virus, tomato spotted wilt, and tomato mosaic. The only solutions to a virus infection is removal of the affected plants and control of the vectors (other organisms, usually insects, that spread the disease). Control of a serious recurring virus problem may require getting help from a Master Gardener, county extension educator, nurseryman, or other qualified person.
Many of the fruit rots and some leaf spot diseases are caused by bacteria. There are no chemical controls for bacteria. The best methods for controlling these diseases are cultural. Keep fruit off the ground and make sure irrigation practices allow plant surfaces to dry between watering. Also, from the garden any refuse from diseased plants.
The most common diseases of plants involve fungal pathogens. Some fungal diseases live in the soil and attack the plant through the roots; other fungal pathogens directly attack leaves, stems, flowers, and fruits. Soil diseases are usually controlled through crop rotation, meaning moving each vegetable to a different place in the garden each year. Fungal leaf and fruit diseases can be reduced my allowing foliage to dry between irrigations and keeping plant parts off the ground. Occasionally, fungal diseases may require fungicidal applications.
To learn more about controlling diseases in vegetable gardens, use the following resources:
University of Idaho: Management of Vegetable Diseases in Home Gardens
Cornell University: Minimizing Diseases in Vegetable Gardens
University of Illinois: Controlling Diseases in the Home Vegetable Garden
After the work, comes the reward. Abundant harvest is the culmination of a vegetable garden well-cared-for. There are important considerations when it comes to harvesting and storing vegetables.
The first decision is when to harvest. Each crop has its own rate of growth and proper stage of maturity. Some are ready to pick within a few weeks of planting, such as radishes or leaf lettuce. Others, such as melons or pumpkins, need the entire summer to mature. It important to acquaint yourself with the vegetables you grow and know about when they will be ready for harvest. Then know what to look for in deciding if the produce is at its optimum stage of growth.
Some vegetables have a long harvest window, while others lose quality very quickly (one day good, the next day not). Generally, the root and tuber crops (e.g. potatoes, carrots, beets) can be successfully harvested over a long span of time. Leaf and flower crops (e.g. head lettuce, broccoli, cauliflower) have a harvest window of one or two days, while fruit crops (e.g. tomatoes, melons) are somewhere in-between. Again, it is important to know your vegetables and be prepared to harvest in a timely manner.
To learn more about harvesting and storing vegetables, see the following resources:
The root and tuber vegetables can be stored in a fresh state for long periods, up to several months under the right conditions (around 40˚F with high humidity). Most other vegetables deteriorate fairly quickly and must be either consumed or processed (frozen or canned) within a short period of time. After harvest, the leaf and flower vegetables must be processed within a few hours. The fruit vegetables may stay in good shape for several days.
To acquire details on canning vegetables, see The National Center for Home Preservation web site USDA Complete Guide to Home Canning, 2009.
Vegetable gardening is a very rewarding activity. In addition to fresh vegetables on the table, it creates feelings of independence and satisfaction, makes a person more self-sufficient, saves money, and is and environmentally sound practice.
For information about individual common vegetable crops in Idaho, see Chapter 21 of the Idaho Master Gardener Handbook.
For more individual crop production information from the University of Illinois, see the Vegetable Directory.
To learn about growing vegetable gardens in Idaho’s short-season climates, reference these three University of Idaho bulletins:
For a general discussion on organic vegetable gardening, see the following University of Florida publication Organic Vegetable Gardening.
This Idaho Vegetable Gardening Guide was written by Dr. Stephen L. Love, Stuart Parkinson, and Dr. Dan Barney and was published in 2011 as part of the Idaho Landscapes and Gardens web site.