Planting vegetables in their right season will greatly enhance your harvest. Most vegetables belong to one of two seasonal groups: cool-season crops and warm-season crops.
The planting date for each vegetable depends upon the weather that the vegetable can best tolerate. Cool-season vegetables grow best in early spring or in late summer and autumn when the weather is cooler. Warm-season vegetables grow best during the late spring, summer, and early autumn when the weather is warm.
Cool-season crops must mature while the weather is cool otherwise they will go to seed. That means they are usually planted at the end of the warm season or the start of the cool season. Warm-season crops must be planted and begin to grow after the last frost or freeze of winter, and they must mature soon enough that they can be harvested before the first frost of the next cool season.
Of course, if the weather in your region is cool year-round, cool-weather crops will be well suited most of the year. And, if you live in tropical or subtropical region where the weather is seldom if ever cool, warm-weather crops are your best year-round choice.
Cool-season vegetables should be planted so that they mature either in the spring or early summer before the heat of summer or later in autumn as the weather begins to cool. Cool-weather vegetables require a minimum planting temperature of 40-50°F (5-10°C), and they grow best when the temperature highs are in the range of 70-75°F (21-24°C).Cool weather crops usually stop producing when daytime temperatures reach 80ºF (26°C). or higher.
Cool-season vegetables that can tolerate frost and or short freezes are classified as hardy and half-hardy according to their tolerance. Hardy vegetables can be planted two to four weeks before the last frost in spring. Their seeds will germinate in cold soil and their seedlings can endure short freezes
Hardy vegetables include:
- Brussels sprouts
Half-hardy cool-weather vegetables are able to tolerate light freezes, just a few hours of freezing weather or frost. Half-hardy crops should be planted about the date of the last spring frost. If they are planted too soon, they will not survive extended freezing weather.
Half-hardy vegetables include:
- Chinese cabbage
- Globe artichokes
Warm-season vegetables require a minimum soil planting temperature of 50°F (10°C). The optimal soil planting temperature for warm-season crops is 60°F (16°C). Warm-season crops do best when the air and soil temperatures reach 65-86° (18-30°C). Most warm-season vegetables require at least 75°F (24°C) for minimum growth.
Warm-season crops can be classified as tender and very tender. Tender vegetables are best planted one to two weeks after the last frost. Very tender vegetables are best planted at least three weeks after the last frost.
Tender vegetables include:
- New Zealand spinach
- Snap beans
- Sweet corn
Very tender vegetables include:
- Lima beans
- Sweet potatoes
Many warm-season vegetables can be grown out of their season if they are protected from temperatures below 50ºF (10ºC). You can use cold frames, row covers, cloches or other season-extending devices to grow warm-season vegetables out of season.
More tips at Seed Planting Times.