James Quinn and David Trinklein
Division of Plant Sciences
Vegetable gardening is a rewarding activity that can provide fresh, flavorful produce. It offers many of the same benefits as other gardening activities, including exercise, fresh air, landscape beautification and enjoyment. In addition, it promotes a varied and nutritious diet at a lower cost by reducing food expenditures more than the costs associated with growing the vegetables. Moreover, many gardeners find that their homegrown produce tastes better than what they can buy at a supermarket, thanks to freshness and more choice of varieties.
Vegetables are defined as "any herbaceous plant whose fruit, seeds, roots, tubers, bulbs, stems, leaves or flower parts are used as food." Herbaceous is a key word here. Vegetables are generally annual plants, whereas fruit crops are produced from perennial plants, such as trees (apples), vines (grapes), bushes (blueberries), canes (raspberries) or crowns (strawberries). If it is produced by an annual, it is most likely a vegetable. There are two perennial vegetables — asparagus and rhubarb — but we eat the stalks of both, not the fruit. Understanding why a plant, such as a watermelon, is considered a vegetable and not a fruit can sometimes seem archaic, but it can be useful to help determine where they will be found in plant and gardening references.
Which vegetables gardeners choose to grow will be influenced by what they like to eat, preserve, process, share — or, for the competitive gardener, exhibit. Family resources of time and energy are also a factor. Some vegetables, such as snap beans or sweet corn, may take more time to manage, from planting through harvest and processing. Space and tools available also help determine what can be grown.
For a large area, the gardener will probably need some motorized equipment, such as a rototiller or even a tractor to turn the soil between seasons. A smaller area can usually be managed with hand tools. Simple hand-pushed planters will probably be adequate for even large gardens.
Some gardeners may prefer to use organic methods, which are covered in more detail in MU Extension publication G6220, Organic Vegetable Gardening Techniques. Some information from this guide on organic vegetable gardening techniques is interspersed in this chapter. Organic gardening may include reduced expenses from lower input costs and possible human and environmental health benefits, but it may require more time and labor, and frequently results in produce with more blemishes due to insect and disease damage. These days, recommended integrated pest management (IPM) approaches to gardening apply many of the same principles and cultural pest controls as organic methods, with an emphasis on maintaining optimal soil and plant conditions to prevent problems.
Selecting a site
G6201, Vegetable Planting Calendar, to see recommended spacing and approximate planting area needed per person for many vegetables' fresh and processed end uses.
Selecting the location for a garden is an important decision. The right spot can make gardening more pleasant and convenient and contribute to plant health and survival. In most cases, the primary considerations for a site are adequate sunlight (a minimum of eight hours in the growing season, preferably with full sun), proximity to supplemental water, soil that is well-drained and deep, and convenience for care and harvest. Of course, soil can be amended, water lines run and trees removed.
When space is limited, intensive techniques, such as raised beds, can help gardeners obtain more crops from an area. One way or another, many homeowners can find a suitable site on their property. The following are several other factors that can influence siting:
- Favored areas of pets and or wildlife that might damage plants
- Tools or equipment needed
- Proximity to trees and shrubs that will shade plants or draw away moisture.
- Compatibility with the landscape design of the yard
To size a garden, gardeners should consider their personal limitations of time and skill, as well as the site, the space requirements of the crops they want to grow and the amount of produce desired. Consider starting small and increasing the size of the growing area as you gain experience. To estimate the production area required for each crop, refer to MU Extension publication
The climate in the central Midwest makes it possible to grow and harvest vegetables from April to October, or even longer for gardeners who make the most of spring and fall crops. To extend the growing season, gardeners can use simple cold frames, greenhouses or even containers that they bring inside on cool nights.
The wide variation in temperature typical of the Midwest, especially in the spring and fall, can challenge the most experienced gardener. If available, a location with a southern or eastern exposure that is sheltered by buildings or trees to the north and west can help create a microclimate to protect against weather extremes such as cold or strong winds. An elevated site that can allow cold air to flow away from plants on clear, still, cold nights is also considered desirable.
All but two vegetable crops — asparagus and rhubarb — are cultivated as annuals. Thus, cold hardiness, which is determined by the lowest winter temperatures typically encountered in an area, has little bearing on vegetable crops. A better guide for vegetable gardening is the American Horticultural Society Heat Zone map (PDF). This map rates most of Missouri as fairly warm, receiving 60 to 90 days hotter than 86 degrees Fahrenheit.
Refined through years of experience and meteorological data, MU Extension publication G6201, Vegetable Planting Calendar, gives recommended planting spring and fall planting dates in south, central and northern Missouri for more than 35 vegetable crops. The publication also provides some basic nutritional information about these vegetables.
A good soil for vegetable production is well-drained and deep. It should contain adequate levels of the major nutrients (phosphorus, potassium, calcium, sulfur and magnesium), a pH of 6.0 to 6.8, and an organic matter level of 5 percent or greater. To achieve all these conditions usually requires amending the soil.
The first step to determine the nutritional status of the soil is to take a soil sample. MP555, Soil Sample Information gives instructions for taking and submitting a sample. Recommendations for adjusting the fertility of soil are provided with the soil test report. It is critical to understand these recommendations as you evaluate what to do with the information. Several useful MU Extension publications provide guidance, including MP733, Lawn and Garden Soil Test Interpretations and Fertilizer Recommendation Guide. However, this information does not account for yield estimates or different crops' specific preferences for nitrogen or pH. Nitrogen recommendations are simplified to one application, generally at planting, based on soil organic matter. Application is usually made by side-dressing. If organic matter is high enough, no nitrogen is recommended. For more detail, gardeners can review recommendations for commercial growers, online at soilplantlab.missouri.edu/soil/trucksoil.htm. Many soils in Missouri and the Midwest are low in organic matter, with levels at or below the recommended 5 percent. This means that soil amendments and additional maintenance steps will often be needed. Several MU Extension publications give useful information on improving soils, each with a slightly different perspective. These include G6955, Improving Lawn and Landscape Soils, G6956, Making and Using Compost, and G6220, Organic Gardening Techniques, which cover manure use, alternative fertilizer sources and cover crops.
Table 1 provides guidance on the level of nitrogen fertilizer recommended for popular vegetables when a soil test is not available. Gardeners can also use the following general recommendations. Apply 1 to 2 pounds of a balanced fertilizer for every 100 feet of row. For an unplanted area, sprinkle 2 pounds of fertilizer for every 100 square feet of garden (2 cups of fertilizer is approximately equivalent to 1 pound by weight). Leafy vegetables (collards, kale, lettuce, mustard, Swiss chard, etc.) benefit from 10-10-10 or 12-12-12 fertilizer formulations. Vegetables grown for fruit, roots or bulbs do best with 5-10-10 or 5-10-5 formulations.
Recommended nitrogen side-dressings for popular vegetables.
|Crop||Ammonium nitrate* per 100 feet row**||Time of application|
(Sprinkle the nitrogen fertilizer in the row middles and water in if rain is not likely.)
|Annual flowers||One pound|
|Cabbage, cauliflower, broccoli||One pound|
|Cucumber, cantaloupe||One pound|
|Onions (mature)||One pound|
|Peas and beans||One pound|
|Peppers, eggplants||One pound|
|Potato||One and a half pounds|
|Spinach, kale, mustard and turnip greens||One pound|
|Sweet corn||One pound|
|Sweet potatoes, watermelons||None|
|Carrots, beets, turnips, parsnips, lettuce||None|
*Other forms of nitrogen such as urea (45 percent N), calcium nitrate (15.5 percent N) and ammonium sulfate (21 percent N) may be used on an equivalent nitrogen basis.
**A pint of ammonium nitrate (33 percent N) weighs approximately one pound.
MU Extension publication
Gardeners typically "work" garden soil one to several times each season. Often, they till soil in the spring to create a favorable seedbed for plants and incorporate soil amendments, and in the fall, to disrupt pest cycles and incorporate organic matter or cover crops. A rototiller or garden tiller is a small mechanized piece of equipment designed for this purpose.
Avoid excess tillage. Overtilling can harm soil structure and create a "hard pan," a hard layer of soil that develops at about the depth that the tiller tines penetrate (4 to 6 inches). For similar reasons, gardeners should avoid working the soil when it is wet.
Supplemental irrigation for gardens is usually necessary throughout the Midwest, especially during the hottest summer months. When irrigating, avoid shallow, frequent doses. It is best to water thoroughly and less often. Shallow watering encourages shallow roots, which makes plants more susceptible to drought.
The best time to water is early morning, about 6 to 8 a.m., because leaves will dry more quickly than in the evening. Evening watering is also fairly efficient, but plants that are susceptible to leaf disease are more likely to be infected if leaves remain wet overnight. The least efficient watering time is during midday when temperatures are high and evaporation is rapid.
Efficient irrigation systems can save a lot of water. Trickle or drip irrigation, including the use of soaker hoses, is the most water-efficient of commonly used systems. Overhead sprinkling generally is less efficient than watering at the soil surface or within the soil. During hot weather, overhead sprinklers lose considerable water to evaporation and runoff. During dry weather, plants need about 1 to 1-1/2 inches of rainfall or irrigation water each week. During very hot weather, their need for water is greater, and watering may be increased up to 2 inches per week.
Although drip irrigation is water-efficient, it makes it difficult to determine how much water has been applied. There always will be more water in the soil closer to the hose or to each emitter than at distances farther away. Check a few spots in the irrigated area by carefully digging out soil with a trowel or spade: The top 6 inches of soil should be moist but not soggy a few hours after the irrigation system has been turned off. If water starts to run off before areas are thoroughly soaked, stop irrigating and do not restart again until the water penetrates so that the soil becomes more absorbent. Efficiency is lost rapidly when water runs off the surface.
If you do use an overhead sprinkler, estimate how much water you have applied by placing wide-mouthed cans or jars with vertical sides within the sprinkler area and measuring the water they collect. Reduce water loss from evaporation by watering during the cooler parts of the day.
Vegetable crops have periods of development when water use is most critical. These periods depend on the type of crop, as indicated:
- Root crops, during root enlargement
- Sweet corn, during tasseling and ear filling
- Cucumbers, pepper, tomato and melon, during flowering, fruit set and fruit development
- Onions, during bulb development
- Potatoes, during tuber initiation and development
Practice crop rotation to improve your garden's soil quality and reduce disease and insect pressure. To rotate crops, avoid planting any vegetable from the same plant family on the same area of ground year after year. The standard recommendation is to plant a vegetable crop from its own family on the same ground only once every three years.
This fundamental cultural practice has been used by gardeners and farmers for centuries. It is still one of the best ways to establish healthy plants and soil and to avoid excessive pesticide use.
Deer, raccoons, woodchucks, rabbits, mice, squirrels and even turtles are often unwanted visitors to vegetable gardens. The first line of defense against browsing wildlife is to try to keep them out of the garden area. Locate the garden plot away from areas that are obvious as favored wildlife areas or travel paths. Leave as much open area as possible between field edges and garden plantings. Fencing will restrict many mammals, but a good fence is expensive. To effectively prevent damage from deer, a fence must be 8-feet tall. For many other garden pests, such as woodchucks or turtles, a fence needs to be dug into the soil about 6 inches.
Commercially available products designed to deter animal pests through scent, sound or touch, are usually only partially effective and can be a problem to maintain. Some animals, including deer, are partially deterred by hanging bars of very fragrant soap near plants. The presence of a dog or a cat may be a more effective choice for control, depending on the pests of concern.
Seeds and transplants
Gardeners can start many vegetables indoors from seed. Species, such as tomatoes, peppers, squash and onions, that are started indoors and then transplanted to the garden will produce an earlier harvest. Some plants, however, such as beans and carrots, are best sown directly outdoors when weather and soil conditions permit.
The proper time for sowing seeds depends primarily on when plants may normally be moved outdoors. This period ranges from four to 10 weeks, depending on the growing conditions and the seedlings' expected growth rate (Table 2). For estimated time of seeding, and growing comments specific to the most common vegetable plants started indoors, see MU Extension publication G6570, Starting Plants from Seeds, which offers recommendations for selecting seeds, containers and soil mixes or other growing media. It also gives step-by-step instructions for seeding, growing, transplanting and hardening off of transplants.
Some gardeners may want to use cold frames to harden off transplants or to start cold-tolerant vegetables, such as lettuce and cabbage, earlier than would possible out in the open. Cold frames, also called hotbeds, are protected plant beds, usually made of a bottomless wooden box with a removable glazed top. They are easy to build and can be made from recycled materials, such as old windows (MU Extension publication G6965, Building and Using Hotbeds and Cold Frames).
Timing to sow vegetable seeds in the home garden.
|Vegetables||Recommended seeding time||Comments|
* Approximate time for seeding is listed for mid-Missouri (Zone 6).
In the Bootheel area (Zone 7), sow about two weeks earlier.
In North Missouri (Zone 5), sow about one week later.
MU Extension publication G6570, Starting Plants from Seeds
Modifying the garden bed
Mulching the vegetable garden is an excellent way to protect the soil, reduce the need to water, decrease the incidence of diseases and weeds, and raise or lower soil temperatures. Natural mulches will generally reduce soil temperature and build organic matter. Plastic or synthetic mulches are typically used to raise soil temperature. MU Extension publication G6960, Mulches, describes commonly used mulches and some of their pros and cons.
Vegetable crops that respond well to mulching are the warm-season crops, beans, peppers, sweet corn, tomatoes and vine crops, and cool-season crops, broccoli, cabbage, cauliflower and potatoes. Keep asparagus and rhubarb constantly mulched to conserve soil moisture and reduce weed problems. Good material for mulching annual vegetable crops includes composts, straw or hay, materials that will be largely decomposed by the end of the season.
Raised beds have become a popular garden modification (Figure 1). Raised beds take a little more time initially to develop, but they offer many advantages, especially in areas such as Missouri that tend to have poor soils. Benefits include improved drainage, increased yields from a small space, an expanded growing season and ease of maintenance. The main disadvantage to raised beds is that increased irrigation is often required to maintain adequate soil moisture in the raised soil area, which tends to warm up and dry out more quickly. See MU Extension publication G6985, Raised Bed Gardening, for more information on construction materials, design, soil mixes and maintenance.
Intensive gardening bed. Raised beds offer many benefits, including improved drainage, increased yields from a small space, an expanded growing season and ease of maintenance.
James Quinn photo
The purpose of intensive gardening is to harvest the most produce possible from a given space. Different approaches to intensive gardening are popular, including "French intensive" and "square foot" gardening methods. More traditional gardens usually consist of long, single rows of vegetables that are often widely spaced. Much of the garden area consists of the space between rows that is not occupied by plants. An intensive garden minimizes wasted space. However, the practice is not just for those with limited garden space; other reasons that gardeners plan an intensive garden include creating an ideal plant environment and obtaining better yields with less labor and other inputs.
A good intensive garden requires early, careful planning to make the best use of space. Interrelationships of plants must be considered before planting, including nutrient needs, shade tolerance, above- and below-ground growth patterns and preferred growing season. The following techniques are common to most high-yielding intensive gardens:
- Raised growing beds
Raised beds are the basic unit of an intensive garden. A system of beds allows the gardener to concentrate soil preparation on small areas, which results in effective use of soil amendments and creates an ideal growing environment.
This practice of growing two or more types of vegetables in the same place at the same time can help reduce weed and pest problems. Proper planning is essential to use interplanting effectively. Though the technique has been practiced for thousands of years, it is just now gaining popularity in this country.
- Close spacing
Individual plants are usually more closely spaced than in a conventional garden. An equidistant spacing pattern is often used that calls for plants to be planted so that the center of one plant is the same distance from plants on all sides. In beds of more than two rows, this means that the rows are staggered so that plants in every other row are between the plants in adjacent rows.
- Succession planting
Successional plantings involve replacing the spent plants of one crop with something new. Again, planning is key to raising a series of crops that will produce from spring through late fall, such as spring peas followed by summer corn succeeded by a fall lettuce crop.
- Relay planting
Relaying consists of overlapping plantings of one type of crop. The new planting is made before the old one is removed. For example, this might be done by seeding three different plantings of green beans two weeks apart.
Studies have investigated which crops bring the most value per square foot of garden space, partly to aid small-space gardeners in making planting decisions. Perennial crops were not considered with this list. Values were based on pounds produced per square foot, retail value per pound at harvest and length of time in the garden. Table 3 shows the general conclusions of this type of analysis, with the highest- and lowest-value crops indicated.
Despite the benefits, the intensive garden may not be for everyone. Some people enjoy the sight of long, straight rows in their gardens. Others prefer machine cultivation to hand weeding. Though there is often less weeding to do in intensive plantings because of fewer pathways and closely spaced plants, the weeding that is needed must be done by hand or with hand tools. Some gardeners like to get their gardens planted in a very short period of time and harvest all at once, later in the growing season. The intensive garden focuses on growing something in every part of the garden during an extended growing season.
The information presented on vegetable culture and harvest is grouped for similar crops that share general growing condition requirements:
- Cool-season crops
Cole crops, greens, radish and turnips
- Root crops
Carrots, beets, onions, garlic and sweet potato
Cucumbers, melons, squash and pumpkins
- Legume crops
Beans, peas and southern peas
- Solanaceous crops
Tomato, potato, peppers, eggplant
- Sweet corn
- Perennial vegetables
Asparagus and rhubarb
Two MU Extension publications, G6201, Vegetable Planting Calendar, and G6226, Vegetable Harvest and Storage, are the source of much of this information. Common vegetable insect pest and disease problems are discussed in several MU Extension publications, including G6203, Common Diseases in the Home Garden and MG13, Preventing and Managing Plant Diseases. Additional Extension publications specific to a vegetable are referenced in that section. Seed catalogs, plant tags and seed packets provide similar information.
Radish, turnips, greens and lettuces and cole crops all grow best in cool conditions. The term "cole" was derived from the Latin word "caulis," which refers to a herbaceous or woody stem that bears leaves and may bear flowers. Cole described the Mediterranean forerunners of our modern cabbages, broccolis, cauliflowers, brussels sprouts and kohlrabi. A cole crop now means any crop from the Brassica genus, which includes all the vegetable crops mentioned, as well as several oilseeds, including canola.
Establish these vegetables in early spring; transplants will likely produce larger plants and greater yields than plants directly seeded in the garden. For both broccoli and cauliflower, the immature flower head is the part eaten. This is usually ready in about 50 to 80 days. Once a broccoli head is cut, secondary shoots continue to grow for about a month; cauliflower does not reliably produce secondary shoots. Broccoli heads turn yellowish when overmature, as the yellow flower buds start to show. For cauliflower, the head may discolor purplish if too mature, or if conditions are too hot when the head, also known as the curd, is swelling. This purple color usually disappears when it is cooked, but the taste may still be bitter. Some cauliflowers require blanching — tying the top leaves up around the developing head to protect it from the sun and keep the white curd from discoloring. Self-blanching cauliflower varieties are now commonly available.
Cabbages grow in a wide range of soil conditions. Depending on the variety, they can be grown in the garden from April through November. Cabbages are referred to as spring or summer. Summer varieties tolerate warmer temperatures and take longer to mature (60 to 70 days versus 85 to 100 for spring types). Savoy cabbage, with its distinctive wrinkled and curled leaves, has a sweet, non-bitter flavor. It can be planted as a spring or a fall crop and matures in only about 55 days. Cabbage heads may split if a heavy rainfall occurs when they are enlarging. Late or summer cabbage keeps well for three to four months if in good condition when harvested and stored correctly (32 degrees Fahrenheit and slightly moist).
Brussels sprouts are more challenging to grow in the spring in Missouri. They take a fairly long time to develop (80 to 100 days). Thus, the sprouts form on the plants as summer heat begins, and they grow bitter if exposed to too much heat.
Insect pests common to cole crops
Common pests of cole crops include cabbage butterfly, cabbage looper (also known as measuring, or inch worm) and imported cabbage worm. Floating row covers can be helpful to exclude pests. Additional control measures include the application of the insecticides carbaryl or permethrin to the foliage, or the use of an organic insecticide.
Greens and lettuce
Swiss chard, spinach, parsley, lettuce, collards and endive should be planted early in the season, from mid-March to early May. They do best in cool, spring temperatures and can provide quick crops. They need plenty of moisture for rapid germination and growth, as most are shallow rooted.
Of the main types of lettuce, leaf, butterhead or Bibb, and cos or romaine, are the most popular and easy to grow in Missouri. Leaf lettuces, colored in a wide range of greens and reds, produce crisp leaves loosely arranged on stalks. Time to harvest may be as fast as 30 days for baby lettuce and up to 60 days for full head development. Bibb and romaine types are more susceptible to heat-related problems such as tip burn than are leaf types.
Swiss chard is from the same family as beets. It is easy to grow and tolerates both heat and cold. Chard is a nutritious, colorful plant that stores longer than most greens. Both its stalks and its leaves can be eaten. A single pl