Depending on your neck of the woods, May is either the beginning of the spring gardening season or getting close to the end. Northern gardeners may not be able to do a whole lot before May, when overnight temperatures finally begin to moderate and the risk of frost lessens. Southern gardeners will already be thinking about when and where to set out corn seed, melons and tomatoes. Whatever the geography, though, there are plenty of chores to be knocked out in the May vegetable garden.
Preparing the Soil
Gardeners in warmer climates are better off preparing the soil in their vegetable beds during the previous fall, since spring planting dates can be as early as February, or January in Texas and Florida. Northern-latitude gardeners, however, can get the beds ready for May planting by beginning to work and amend the beds as soon as the soil can be worked, usually in March or April. During this time, gardeners should focus on clearing out roots from the previous year, and amending garden soil with additives such as peat moss, humus and compost. A balanced, all-purpose, slow-release fertilizer should be added at this time, as well.
Vegetables for Spring
Northern gardeners planting in May can plant seed for traditional spring crops such as peas, carrots, radishes, lettuce and spinach as soon as the soil can be worked. If temperatures are still quite cold at night during the month of May, crops like lettuce, cabbage and broccoli mature faster when started indoors under plant lights and set out in May as well-established transplants. Peas should be planted as soon as possible, as seed germinates poorly in soils which have become too warm. Other cool-season spring crops include kale, rapini, Swiss chard and Asian greens like bok choy and tatsoi. Southern gardeners will be able to put in summer crops like tomatoes, melons and peppers during May, or even earlier.
To avoid a glut of vegetables ripening all at once, many gardeners use the practice of succession planting. By planting seeds over several weeks, gardeners can space out the harvest. This can mean the difference between 2 lbs. of carrots ripening all at the same time or over a period of two or three weeks. Sowing one row of seed per week for three or four weeks will give the gardener a longer overall harvest period, and can make up for reduced yields due to late frosts or other plant failures.
Especially in zones to the north of the United States' midsection, frosts after May 1 are not an uncommon occurrence, and those gardeners should be prepared to protect crops from late-season freezes. A wide variety of commercial devices are available for this purpose. Hot caps are any type of container placed directly over a young plant to help keep it from freezing overnight; they should be removed during daylight hours. Water walls are cylinders with fluid-filled exteriors that are placed over plants during the night; the water helps keep the temperature inside the cylinder above freezing. Hot caps are among the easiest type of frost protection device to make at home: inverting an empty yogurt container or placing a sawed-off plastic beverage bottle over a plant achieves the same effect.
Many farmers and gardeners also use floating row covers to keep temperatures above freezing. Row cover fabric is made from spun polyethylene fibers, and when placed over a garden bed will trap heat beneath it. Taller plants can be protected by using row covers stretched over hoops, which keeps the fabric from rubbing against and damaging the sensitive growing tips.
Planning for Later Crops
The process of visualizing how a garden will unfold over the growing season is much simplified by preparing a garden blueprint. Begin by drawing up a sketch of the garden as it appears in the spring, then make a second sketch for the summer planting based on how long it takes each of the spring crops to reach maturity. For instance, peas, which are early to ripen, can be followed by tomatoes, or spinach followed by beans.
Be sure to take into consideration factors like total time required for crops to fully ripen: carrots take much longer to mature than leafy greens, for example. Some types of onions may take up to a year before they are ready for harvest, and most winter squashes require a very long growing season. Counting backward from the average first frost date in the fall can help you get a handle on when you should be planting each crop throughout the year.