Most vegetable gardeners need a year or two of trial and error plantings and attentive record keeping to know when is the best time to plant in their garden.
To start a vegetable garden, pay attention to the temperature. Your growing season happens between the last killing freeze of spring and the first killing freeze of fall. The exact date of the last and first freeze each year will vary—but you will soon notice there’s an average (check weather records online to see the pattern for your area).
By season, here is guide to planting vegetables:
• Early Spring, as soon as the ground can turned with a shovel but before the last frost: Broccoli plants (starts, not seeds), Cabbage plants, Endive, Kohlrabi, Lettuce, Onion sets, Parsley, Peas, Radishes, Spinach, Turnips (these plants want to mature before average temperatures reach much above 65°F).
• Mid-Spring, at about the time of the last killing frost: Carrots, Cauliflower plants, Beets, Onion seeds, Parsnips, Swiss Chard; two weeks after the last frost: Beans, Corn, Potatoes, early Tomato seeds.
• Early Summer, when the soil has warmed to 65°-85° range: Lima Beans, Cantaloupe, Celery plants, Crenshaw melons, Cucumbers, Eggplant plants, Pumpkins, Pepper plants, Potatoes for winter, Squash, Tomato plants, Watermelons.
• Mid-Summer—Fall, plant in early summer: Beets, Broccoli, Cabbage, Cauliflower, Kohlrabi, Lettuce, Radishes, Spinach, Turnips (these plants will mature in the cool temperatures of autumn).
Here are more helpful articles on Planting and Weather: