Tomatoes (Solanum lycopersicum) are garden annuals that produce the most fruit when temperatures are within a specific range. For Virginia gardeners, this means the ideal time to plant tomatoes is in a window in spring that takes advantage of the plants' temperature preferences.
Beat the Heat
To grow well and best produce fruit, tomatoes need warm weather, but temperatures that are too high have the opposite effect and hinder the plants' fruit production. When daytime temperatures are above 90 degrees Fahrenheit and nighttime temperatures are above 70 F, plants may fail to set fruit.
Consequently, the ideal time to set tomato transplants in a Virginia garden is as early as possible so that the plants have time to produce an adequate crop before the hottest part of the summer, when high temperatures are likely to slow fruit production. However, tomato plants are frost sensitive, so they can't be set out before the last frost in the spring.
In Virginia, the range of typical planting dates for tomatoes begins at the date of the last expected frost and extends for approximately the next seven weeks, a schedule that has the harvest period beginning as early as mid-June in the warmest parts of the state.
Last Frost Dates
The Tidewater region of eastern Virginia has the earliest frost-free dates in the state, with an average date of the last spring frost falling between April 10 and April 21. The Piedmont region of central Virginia is next; here the average date of the last frost is between April 20 and April 30. The Mountain region in the west has the latest frost-free dates; in this region, the average date of the last frost comes between May 10 and May 15.
Given these frost dates, the range of acceptable planting dates in the Tidewater region is between April 10 and May 30. In the Piedmont, the range lies between April 20 and June 9, and in the Mountain region, the range is between May 10 and the end of June.
Planting early within these ranges gives tomato plants the best chance of producing a good crop before the onset of midsummer heat, but it also exposes transplants to the danger of a late frost at the beginning of the season.