Lynda Bevere
WHAT IS THE DIFFERENCE BETWEEN WARM AND COOL SEASON CROPS (When to Plant What Vegetables?)
What is the difference between warm and cool season crops? In general, warm season vegetables thrive in the warmer temperatures of the summer and cool season vegetables grow best in the cooler months of the spring and fall.
New gardeners often believe that vegetables only grow in the summer months. This is not true. For example, vegetable gardening season here in New Jersey USDA Zone 6 is from March to November and in some warmer zones, all year long. If you want to successfully grow a variety of vegetables and extend your harvest as long as possible, it is important that you are aware of the difference between cool and warm season crops and to know when you should plant and harvest them.

Cool Season Vegetables
Cool season crops are vegetables that thrive in the cooler months of spring and fall. Most cool season crops are frost resistant with some exceptions such as carrots, potatoes and some greens, such as swiss chard. These frost sensitive vegetables should not be seeded until later in the spring.
Plant cool season crops when the soil is workable. Workable soil is no longer frozen and crumbles in your hand. If you can create a ball with the soil, it is too wet and it needs to dry out before planting. In general, you can start planting cool season crops outdoors from seed or seedlings (baby plants or transplants) in mid-March (here in USDA Zone 6) or 4 to 6 weeks before last spring frost wherever you live. Harvesting spring cool season vegetables starts in April and lasts into the summer months.
For a fall harvest, start growing cool season vegetables from seed or seedlings (transplants) in early September (here in USDA Zone 6) or about 8 weeks before the first fall frost where you live. These crops will be available for harvest in October to November.
List of Cool Season Vegetables:

Beets
Broccoli
Cabbage
Carrots*
Cauliflower
Kale
Lettuce
Onions
Parsnips
Peas
Potatoes*
Radishes
Swiss Chard*
(*frost sensitive)
Warm Season Vegetables
Warm season crops are vegetables that die or are severely harmed by frost and thus should not be planted until after the last frost day of your growing zone. There is no benefit to rushing the planting of these warm season vegetables because they will not grow well until the ground warms up. The temperature should be at 50 degrees or above. Seeds of these crops also do not generally germinate reliably until temperatures are near 60 degrees. Warm season crops are harvested from early summer until the first fall frost.
List of Warm Season Vegetables:

Beans (Bush and Pole)
Corn
Cucumbers
Eggplant
Melons
Peppers
Squash (winter and summer)
Tomatoes