There are 11 hardiness zones in the United States. The orange color shows when to start seedlings indoors, the yellow is times to transplant or direct sow and the green is harvest dates. Custom programming and server maintenance by Reinvented Inc.. Connect With Us Scroll down to see the vegetable planting guide. The expected first frost dates are September 30 to October 30. To find your USDA hardiness zone, click the link. If you planted any winter lettuce, spinach, and parsley, you need to protect them from upcoming frost. Enter the code on the security pop-up (it is case-sensitive), then enter your ZIP Code to see your zone. Gardeners who live in warmer growing zones, such as those above zone 7, should plant their delphiniums where they will be protected from hot, direct sunlight, and where the soil is shaded. Seeding: Last chance to plant spring bulbs, winter lettuce, and spinach.. Zone 7 has expected last frost dates between March 30 and April 30. Harvest: Any remaining carrots, kale, cabbage, and Brussels sprouts.. Hardiness zones are determined by frost dates (the last expected frost in the spring and the first expected frost in the fall). At the beginning of the month, you can still plant shrubs, trees, and strawberries. Temperature: 45 to 66 F (10 to 19 Celsius).