Collards (Brassica oleracea) can be grown most of the year in South Carolina, though early spring or fall production is generally preferred. Mature plants will withstand frosts and light to medium freezes. Collards may be grown in a variety of soils. In the spring, select a bolting tolerant cultivar, meaning it will not readily develop a flower head when exposed to cold following a favorable growing period. Eventually, any cultivar will bolt
|Piedmont||Mar. 15-June 30||July 15-Sept 30|
|Central||Feb. 15-June 15||July 15-Oct. 15|
|Coastal||Feb. 1-June 15||Aug 1-Oct. 30|
Transplants are the preferred planting material for a spring crop, as seeds germinate slowly in cool soil in the spring. Start seeds indoors six to eight weeks prior to the desired planting date. Plant collards in rows that are 18 to 36 inches apart. Space plants 6 to 18 inches apart on the row.
Direct seeding works well when planting in the late summer for a fall harvest, as the soil is much warmer at this time. It is critical to keep the soil moist during seedling establishment. Plant seed in moist soil about ¼ to ½ inch deep. Seeds planted deeper than ½ inch likely will not germinate. Thin plants to the desired stand when they are in the three-leaf stage.
When planting for microgreens, always select seeds that have not been treated with an insecticide or fungicide.
Most collard cultivars are bred to be slow to bolt. The cultivars listed below are just a few of many good available options.
- Blue Max
- Top Bunch 2.0
- Georgia Southern
- Morris Heading
Collards require moderate amounts of fertilizer. A soil test is always the best method of determining the fertilization needs of the crop. For more information, see HGIC 1652, Soil Testing. Follow the results of a soil test to maintain a soil pH between 6.0 and 6.5.
Apply preplant fertilizer according to soil test recommendations. Broadcast the fertilizer evenly and incorporate it into the soil by tilling or discing to a depth of around 6 inches. Working the fertilizer into the soil ensures that the nutrients are available to the plants when they are seeded or transplanted.
Nitrogen is essential for collards to produce high-quality leaves. Side dress the plants with 5 pounds of calcium nitrate (15.5-0-0) per 1000 square feet or 300 feet of row three to four weeks after planting. For smaller gardens, use ½ pound of calcium nitrate fertilizer per 100 square feet or 30 feet of row. A pint is roughly equal to a pound for most fertilizers. Side dress another 5 pounds per 1000 square feet or ½ pound per 100 square feet three to four weeks after that. To avoid burning the roots, place side-dress fertilizer 4 to 6 inches away from the plants. If fertilizer is broadcast, avoid burning the plant foliage by watering overhead after the application to wash the fertilizer granules off the leaves.
Water the garden to provide a uniform moisture supply to the crop. Leaves will become wilted and limp when soil moisture is insufficient. Water early in the day to allow the leaves to dry before nightfall. This will aid in avoiding foliar plant diseases. Water sufficiently to moisten the soil to a depth of at least 6 inches, as light sprinklings will encourage shallow rooting. The critical periods for moisture are at stand establishment and crop maturation. Mulching can help conserve water and reduce weeds.
Harvesting & Storage
Collards should be ready for harvest 60 to 80 days after direct seeding, depending on the cultivar. Microgreens will be ready to harvest 10 to 15 days after seeding. Entire plants may be cut when half-grown or full-grown. To extend the harvest, break off individual leaves starting from the bottom of the plant and move up over time. Pick only a few leaves from each plant to give the plant time to recover. Collards can be stored in a plastic bag in the refrigerator for up to 2 weeks.
Several caterpillars (imported cabbageworm, cabbage looper, diamondback moth caterpillar), and harlequin bugs are the major insect problems. Aphids may be an occasional problem, most commonly in the fall. For more information about collard insect pests, see HGIC 2203, Cabbage, Broccoli, and Other Cole Crop Insect Pests.
Common disease problems include black rot, downy mildew, and Alternaria leaf spot. Fusarium yellows may be a problem on summer-grown collards. For more information about diseases affecting collards, see HGIC 2202, Cabbage, Broccoli, and Other Cole Crop Diseases.