Collard Greens in Zone 7B — Southeast

Collard greens are a Southern staple for a reason. Their slightly bitter, earthy flavor is fantastic braised, sautéed, or even added to soups. Here in the Southeast, with our long summer, collards thrive, giving you a steady supply of nutritious greens from late spring well into fall.

Our hot, humid summers and clay soil can present challenges, but collards are surprisingly resilient. With a little attention to timing and watering, you can easily grow a bountiful crop. Our 235-day growing season gives you plenty of opportunities to get it right, whether you start seeds indoors or directly sow them in the garden.

Starting collard greens indoors in the Southeast isn't always necessary, given our long growing season, but it can give you a head start, especially for an earlier spring harvest. If you want to get a jump on things, sow your seeds indoors from mid February through early March, about four weeks before you plan to transplant them outside.

Use seed trays or small pots filled with a good seed-starting mix. Keep the soil consistently moist by bottom watering – set the tray in a shallow dish of water and let the soil absorb it from the bottom. This helps prevent damping-off disease. Place the trays in a warm location with plenty of light, either from a sunny window or a grow light. Remember, our spring weather can be moderate, so protecting seedlings indoors for a few weeks can be beneficial.

Transplant your collard green seedlings outdoors from mid March through mid April, once the danger of a hard frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Start with an hour or two of shade and slowly increase the time and sun exposure each day.

When transplanting, space your collard greens 18-24 inches apart in well-drained soil. Even though our weather is usually warming up by this time, keep an eye out for late cold snaps that can stress young plants. Water them well after transplanting to help them settle in.

Direct sowing collard greens is a great option in the Southeast, especially since we have such a long window to do it. You can direct sow from early March through mid August, giving you plenty of flexibility. The later you sow, the better for avoiding early Japanese beetle damage.

Prepare your soil by loosening it and adding compost or other organic matter. Sow seeds ½ inch deep and 18-24 inches apart. Keep the soil consistently moist until the seedlings emerge, usually in about a week. Direct sowing is simple, but remember that young seedlings are more vulnerable to pests and diseases than transplants.

Consistent watering is key to growing healthy, tender collard greens in the Southeast. While collards are more heat-tolerant than some brassicas, they still need regular moisture, especially during our hot and humid summers. Aim to keep the soil evenly moist, but not waterlogged.

During the spring and fall, when temperatures are milder and rainfall is more frequent, you may only need to water once or twice a week, depending on rainfall. In the heat of summer, you might need to water every other day, or even daily during dry spells. The best way to check is the "finger test" – stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water.

Give your collards about 1-1.5 inches of water per week, either from rainfall or irrigation. Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our humid climate. Signs of underwatering include wilting leaves, while overwatering can lead to yellowing leaves and root rot. A layer of mulch around your plants will help retain moisture and suppress weeds, which is especially helpful in our hot, humid summers. Pine straw or shredded leaves work great.

You can expect your first harvest of collard greens about 75 days after planting, so from mid May through mid November, depending on when you planted. The lower leaves are ready to harvest when they are 10-12 inches long and a healthy green color.

To harvest, simply snap or cut off the outer leaves, leaving the top rosette intact. This allows the plant to continue producing new leaves throughout the season. Collard greens actually taste sweeter after a frost, so don't be afraid to leave them in the garden until early November.

As the first frost approaches, harvest any remaining large leaves to prevent them from being damaged. You can blanch and freeze them for later use. Even after a light frost, the central rosette may survive and continue to produce new growth, giving you a few more harvests.

Here are some common problems you might encounter growing collard greens in the Southeast:

Cabbage Worms

• What it looks like: Smooth green caterpillars chewing irregular holes in leaves. You might also see dark green droppings and white butterflies fluttering around.
• What causes it: These are the larvae of white cabbage butterflies. They have multiple generations per season in our warm climate.
• How to fix/prevent it: Bt spray is very effective. Floating row covers can prevent the butterflies from laying eggs. Handpick caterpillars whenever you see them. Interplant with aromatic herbs like thyme and sage to deter them.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. You might also see sticky honeydew residue and curled or distorted new growth.
• What causes it: Aphids are sap-sucking insects that reproduce rapidly, especially in warm weather. Ants often "farm" them for their honeydew.
• How to fix/prevent it: A strong spray of water can knock them off. Encourage ladybugs and lacewings, which are natural predators. Insecticidal soap works well for heavy infestations. Avoid over-fertilizing with nitrogen, as this attracts aphids.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but these caterpillars move in a looping motion. They also chew holes in leaves.
• What causes it: Cabbage loopers are the larvae of a gray-brown moth. They thrive in warm weather.
• How to fix/prevent it: Use Bt spray, handpick caterpillars, and use floating row covers. Encourage natural predators like parasitic wasps.

Downy Mildew

• What it looks like: Yellow patches on leaf tops with fuzzy gray-purple growth on the undersides. Leaves eventually brown and die from the bottom up.
• What causes it: This is a fungal disease that spreads in cool, humid conditions via wind-carried spores.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation by spacing plants properly. Water at the base of the plants, never overhead. Copper-based fungicides can help prevent the spread.

Southeast Specific Challenges: The hot and humid climate of the Southeast can exacerbate these problems. High humidity promotes fungal diseases like downy mildew, while our long, warm summers allow pests like cabbage worms and aphids to thrive. Regular monitoring and proactive measures are key to keeping your collard greens healthy.

Companion planting can be a great way to improve the health and productivity of your collard greens. Onions and garlic are good companions because their strong scent can deter pests like aphids and cabbage moths. Beets and potatoes are also good neighbors, as they don't compete for the same nutrients and can help improve soil health. Dill attracts beneficial insects like ladybugs and lacewings, which prey on aphids and other pests.

Avoid planting strawberries or tomatoes near your collard greens. Strawberries can attract slugs and snails, which can also damage collard greens. Tomatoes can compete for nutrients and water, and they can also attract pests that affect collards.