When Can I Plant My Garden Vegetables?

Vegetable gardening is a favorite hobby and, in some cases, a necessity for many homeowners throughout the United States. A fresh supply of colorful greens, root vegetables and other tasty selections can make your summer salads shine while canning and other preservation methods help extend your harvest to allow you to have fresh, nutritious vegetables throughout the year. Knowing when to get your seeds or transplants in the ground can mean the difference between a substantial harvest and one that misses the mark.

Understanding your location's climate, seasonal changes and weather shifts can greatly aid you in planting your vegetables, whether in spring or fall. The first and last average annual frost dates will give you a good idea of when to plant. Even though the first and last frosts vary from year to year, their average annual dates are the ones most commonly used for vegetable planting calendars.

Not all vegetable plants can handle the same amount of shade or sunlight, or the same temperatures. Some vegetable crops grow better in cool weather while others need the long, hot days of summer to produce fully. Lettuce (Lactuca sativa), peas (Pisum sativum), garlic (Allium sativum) and the Brassica oleracea group, which includes broccoli, cauliflower, kale and cabbage, are among those that do best with cool temperatures and are well-suited to fall or early spring planting. In early spring, you can plant most of these cool-season vegetables as soon as your soil is workable and thawed.

Most corn (Zea mays), tomatoes (Solanum lycopersicum) and peppers (Capsicum spp.) require summer temperatures to produce fruits and, therefore, thrive when planted in mid-spring.

Another important factor to consider is the time to harvest, sometimes written as "days to maturity" on seed packets and meaning the number of days from planting to harvest. For example, most corn and tomato varieties have long periods from planting to harvest while radish (Raphanus sativus) and leaf lettuce mature in 25 and 40 days, respectively.

In general, most summer vegetables -- those ready for summer harvest -- can be planted as soon as the average annual last frost date in spring passes. Those vegetables include corn, tomatoes, peppers, eggplant (Solanum melongena), several squash (Cucurbita spp.), watermelon (Citrullus lanatus), sweet potatoes (Ipomoea batatas) and cucumbers (Cucumis sativus). In the Midwest and a few other U.S. areas, a general rule of thumb is to wait until Mother's Day to plant summer vegetables; however, the planting date differs throughout the country. In South Carolina, for example, spring planting dates are as early as mid-March for many crops.

The fall vegetable garden is a foreign idea for many people, but gardening into autumn is a way to extend your harvest season. Planting dates for fall harvests typically are in late summer. If you want to plant tender vegetables, then learn how many days they require between planting and harvest, and put them in the ground at least that many days before your area's average annual first frost date. If, for example, a tender vegetable takes 45 days to be ready for harvest and your average annual first frost date is Oct. 30, then plant the vegetable before Sept. 15.