HO-186
Indiana Vegetable Planting Calendar

HOME YARD & GARDEN • COOPERATIVE EXTENSION SERVICE
DEPARTMENT OF HORTICULTURE • PURDUE UNIVERSITY • WEST LAFAYETTE, IN
by Michael N. Dana and
Allen E. Boger, Extension Agent, Vanderburgh County

Planting vegetable seeds or transplants at the correct time is an important step toward a successful garden. The correct timing is determined by the soil temperature required for seed germination and the temperature tolerance of the plants. The best date for planting can vary from season to season. It also differs from one location to another based on the microclimatic effects of urban areas, natural terrain, moisture, sunlight, wind exposure, and garden devices such as cloches and mulches.
Because of this variation, we can only suggest a range of safe planting dates based on the average dates of the last normal freeze in the spring (Figure 1) and the first freeze in the fall (Figure 2). You should note the current weather conditions and projections as well as site conditions in determining the correct planting date for a specific crop and variety. To increase the likelihood of success, it is suggested that you plan to make several plantings within this range of dates. This will also extend the harvest season over a longer period of time. When only one planting is planned, make it about midway through the range. Table 1 indicates spring
planting dates, while Table 2 suggests appropriate dates for fall garden planting.

Soil Temperature
Many summer vegetable crops do not grow well until the soil temperatures are warm. In years when cool air temperatures and rainfall do not allow the soil to warm up, delay planting warm season crops such as beans, tomatoes, squash, sweet potatoes, and peanuts until the soil temperature is suitable for optimum germination and/or growth. Otherwise, seed and root rot disease and related disorders are likely to occur.
For more experienced gardeners, soil temperature measurements offer an alternative to planting according to frost dates. Soil can be warmed early by the use of black or clear plastic mulches. Seeds which require warm temperatures for germination can then be planted successfully before the recommended dates. However, protection against late frosts for the seedlings may be required. Table 3 provides seed germination temperatures for several vegetables.