Collard greens are a leafy, cool-weather vegetable belonging to the Brassica oleracea species, a relative of cabbage and kale. Unlike many of its cousins, collards grow as a loose bouquet of leaves rather than a tight head. The crop thrives in cooler temperatures and can tolerate a wide range of conditions. USDA Hardiness Zone 7, defined by average minimum winter temperatures ranging from 0°F to 10°F, offers two distinct, extended planting windows for a long and productive harvest.
Spring Planting Schedule for Zone 7
The spring planting window is calculated by working backward from the average last expected frost date, which typically falls around April 15th in Zone 7. Collard greens are cold-tolerant, allowing for planting much earlier than many other vegetables. Starting seeds indoors approximately six weeks before the last frost date is the most reliable method for a head start. Sow seeds in trays about 1/4 to 1/2 inch deep to ensure the seedlings develop a strong root system.
Once the seedlings have been growing for four to six weeks, they are ready to be moved outside. Transplanting can safely occur two to four weeks before the average last frost date, usually from mid-March to early April. This timing takes advantage of the collard’s ability to withstand light frosts and temperatures down to the upper teens. Direct sowing outdoors can also be done when the soil can be easily worked, but transplanting offers a more consistent and earlier harvest before the peak heat of summer.
Maximizing the Fall and Winter Harvest
The fall planting season is preferred because the resulting leaves offer superior flavor. This improvement occurs after a light frost, which triggers a biological process converting starches into sugars. The average first frost in Zone 7 is around November 15th. To ensure the plants reach a harvestable size before the first hard freeze, seeds should be direct-sown or transplanted six to eight weeks prior.
This means planting is scheduled for late August through mid-September, allowing the collards to mature just as the cool weather arrives.
Collards planted in the fall can often be harvested well into the winter months in Zone 7, a practice known as overwintering. Mature plants continue to produce new leaves even after several light frosts. Gardeners can use a row cover or cold frame to protect the crop and extend the harvest season.
Essential Growing Conditions
Collard greens require consistent environmental factors to ensure rapid growth and tender leaves. They flourish best when given full sun (six to eight hours of direct sunlight daily). While they will tolerate partial shade, sufficient light is necessary for robust leaf development.
The plant needs fertile, rich, and well-draining soil that has been amended with organic matter like compost. Collards prefer a slightly acidic to neutral soil pH, ideally ranging between 6.0 and 6.8, to discourage common diseases. Consistent soil moisture is required, typically 1 to 1.5 inches of water weekly from rainfall or irrigation.
Proper spacing is necessary for good air circulation and plant health, preventing the spread of fungal issues. When planting for a full-sized harvest, each plant should be spaced 18 to 24 inches apart. This spacing allows the large, loose leaves to fully develop and ensures the best possible yield and quality.