Good planning is essential to a successful vegetable garden. Vegetables have specific requirements, and you must choose your site carefully to ensure a bountiful harvest. Here are the basics you need to consider before you select your seeds. (Martha's vegetable garden at her home in Bedford, New York, is at left.)
Drainage is the soil's ability to absorb moisture and let excess water drain away. You can test soil drainage by digging a hole a foot deep and a foot across. Fill the holes with water, and time how long it takes the water to drain away; two to three hours after the hole has emptied, refill it, and again time the interval it takes for it to empty. Then calculate the rate of drainage by dividing the total depth of the water (24 inches) by the total number of hours it took for the hole to empty two times.
An average rate of an inch of water lost per hour makes a "well-drained" soil, which is best for vegetable plants. A substantially faster rate is typical of a "sharply drained" soil, one that dries out quickly, and unless enriched with water-retaining compost, is suitable mainly for drought-tolerant plants. A drainage rate markedly slower than an inch per hour indicates poorly drained soil, which will probably drown the roots of most plants.
To help you select the plants that prefer your climate, use the "Zones of Hardiness Map" published by the United States Department of Agriculture. This map divides the United States and Canada into 11 zones. Because winter cold is, in most regions, the single greatest threat to plant survival, the zones are divided according to the average monthly temperature they experience locally.
Plant descriptions in catalogs and labels typically refer to these hardiness zones to specify the areas in which any given plant will thrive. Once you have identified the zone in which your garden is located, purchase only plants recommended as reliably hardy there.
Note: If you plan to grow perennial vegetables, like asparagus and artichoke, you'll need to identify your hardiness zone. Though your zone doesn't necessarily dictate which annual vegetables, like tomatoes and lettuce, you can grow, it can inform you about which specific varieties will do best in your area.
In general, plants described as requiring "full sun" (most vegetable plants fall under this category) need at least six hours of exposure to direct sunlight daily. "Part sun" or "semi-shade" plants flourish where periods of direct sunlight alternate with periods of shade, or where the sunlight is filtered by an intermittent canopy of branches or a trellis overhead. "Full shade" describes a spot where direct sunlight never penetrates, due to shadows cast by dense evergreens or solid man-made structures, such as a high wall or porch roof.
Open-Pollinated (OP): These plants come from a parent of the same variety and they can, in turn, produce offspring of the same variety. This is called "coming true from seed." The seed from open-pollinated varieties can be collected from the plants you've grown and saved to grow again next year.
Heirloom Vegetables: Heirlooms are open-pollinated varieties that have been cultivated for at least 50 years. They are often more flavorful, colorful, and interesting than hybrids, but they may lack disease-resistance or require staking.
Hybrids: These plants are the result of cross-breeding to produce offspring with certain desirable traits, such as disease-resistance or uniform color or size. Their complicated genetics mean that the seed inside the fruit you grow one season will not produce a plant like its parent. Each year, you will have to buy new seeds of this variety if you want to grow it again.
Vegetable crops fall into two categories:
Cool-Season Crops: Peas, lettuces, radishes, brassicas (broccoli, kale, cauliflower, collards), and spinach germinate and thrive in the lower temperatures of spring and fall and tolerate light frosts. Many cool-season crops can be direct-sown in the garden around before the last frost.
Warm-Season Crops: Tomatoes, eggplants, summer and winter squash, beans, and corn prefer summer's heat. Plant these only after the soil has warmed. Many warm-season crops require a long growing season and should be started indoors in late winter or early spring or purchased as seedlings ready to be transplanted.
Sketch out your plan on paper. Use graph paper and draw to scale, keeping in mind the mature size and habit of each kind of plant. Site larger plants like corn and tomatoes where they won't cast shade over shorter plants. Choose compact varieties if you have limited space. Start small: You can always dig more beds or enlarge existing ones in subsequent years.