Use Historically Recommended Planting Dates as a Guide

Recommended planting dates for spring vegetables are available for commercial growers in the Mid-Atlantic Commercial Vegetable Production Recommendations and for gardeners in this factsheet. These planting dates are based not only on the crop’s tolerance of cold weather but also on their time to maturity and desired harvest window. For example, Brussels sprouts are cold tolerant, but they are transplanted in June for fall harvest because they require a long growing season. To adapt to warmer spring conditions and a longer growing season, choose dates earlier in the planting window for cool season crops, especially those that are prone to quality problems when exposed to heat (i.e., lettuce, cauliflower, broccoli, snap beans). In many years, warm season crops can be planted early in their recommended window to achieve an earlier harvest.

Variety Selection

For cool season crops that might be impacted by unseasonably hot conditions in April, May and June, choose varieties with heat tolerance. Heat tolerant lettuce varieties will be less prone to bolting and turning bitter tasting. Heat tolerant broccoli and cauliflower are less prone to quality reducing physiological disorders. Another strategy to avoid damage from heat stress is to plant several varieties with different days to maturity. (Many seed catalogs offer variety mixes for some crops.) Planting several varieties makes it less likely that all the plants will be at the heat susceptible growth state during a period of hot weather. A similar approach is to make sequential plantings of the same variety during the entire planting window.

Check the Forecast Before Planting

Before deciding on an early planting date, check the weather forecast to determine if predicted conditions will support plant growth. This is especially important if you are planting cold sensitive crops early. If you are in a freeze prone site, note any predicted clear nights which could result in frost even if temperatures are not forecast to drop to 32 °F. Try to plant at a time when temperatures are expected to be warm for a few days afterward. When direct seeding, warm temperatures promote faster germination resulting in less exposure to insects and diseases that impact seeds. Transplanting at the beginning of a warm period allows plants to quickly root into the soil, improving their stress tolerance. Also, avoid transplanting right before forecasted strong winds, which can quickly dry out transplants that have not yet rooted into the soil.

Acclimate Transplants

Make sure that transplants have the best chance of survival by acclimating them to higher light and lower humidity conditions before planting. Transplants should be moved from the greenhouse to an outdoor location in partial sun and protected from excessive wind. Maintain transplants in these conditions for a week before planting to the field. Move or cover transplants if very cold or windy conditions are expected.

Be Ready to Frost Protect

Even though some recent spring seasons have been warm, we have still had years with very late frosts (such as in 2020), so be prepared to protect sensitive plants if freezing conditions are predicted. Some crops like potatoes and sweet corn will regrow if the plants are still small when frost damaged. Other crops like tomatoes, peppers and melons will not regrow if plants are frozen. Row covers can be used to protect frost sensitive vegetables that have already been planted in the field. Home gardeners can use blankets, sheets or buckets to cover freeze sensitive plants if cold temperatures are expected. Covers should be applied in the late afternoon before air temperatures fall to retain heat accumulated in the soil.