Collard Greens in Zone 6B — Great Plains

Collard greens are a fantastic addition to any Great Plains garden. Their slightly bitter, earthy flavor mellows beautifully when cooked, making them incredibly versatile in everything from Southern-style braises to stir-fries. Plus, the satisfaction of harvesting your own greens well into the fall, even after a light frost, is especially rewarding in our variable climate.

Our region can throw some curveballs, with extreme temperature swings and the ever-present threat of hail. However, with a 198-day growing season, you can easily time your collard crop for success. Careful planning lets you enjoy a long harvest window.

Starting collard greens indoors is an option, especially if you're aiming for the earliest possible harvest. Start your seeds indoors from early to late March, about four weeks before you plan to transplant them outside. Use seed trays and a good seed-starting mix, providing warmth and plenty of light – a grow light is really helpful this time of year.

Make sure to water from the bottom to prevent damping-off. In the Plains, spring weather can be so unpredictable, so starting indoors gives you a head start and protects seedlings from those early temperature swings.

Transplant your collard greens outdoors from early April through early May. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

Space your plants 18-24 inches apart to give them plenty of room to grow. Keep an eye on the weather forecast, as late frosts are always a possibility. If a frost is predicted, cover your young plants with row covers or blankets.

Direct sowing collard greens is a straightforward and reliable method, especially for a later harvest. Sow your seeds directly into the garden from late March through late July. Prepare the soil well, ensuring it's loose and fertile. Collard greens seeds germinate best when the soil temperature is above 60°F (15°C).

Plant seeds about ½ inch deep and space them 18-24 inches apart. Thin seedlings as needed to ensure proper spacing. Direct sowing is a great option if you want to avoid the hassle of indoor starting and transplanting, but keep in mind that germination can be slower in cooler soil.

Collard greens need consistent moisture to thrive, especially in our Great Plains climate. Aim for about 1-1.5 inches of water per week, either through rainfall or irrigation. The "finger test" is a good way to check soil moisture: stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water.

In the hot summer months, you may need to water more frequently, especially during dry spells. Water at the base of the plants to avoid wetting the leaves, which can encourage disease in our low-to-moderate humidity. Overwatering can lead to root rot, so make sure the soil is well-draining.

Signs of underwatering include wilting leaves and slow growth. Overwatering can cause yellowing leaves and stunted growth. A layer of mulch around your plants helps retain moisture and regulate soil temperature.

You can expect your first harvest of collard greens from early June through early November, about 75 days after planting. Harvest the lower leaves when they are 10-12 inches long, leaving the top rosette to continue growing. The flavor of collard greens actually sweetens after a light frost, so don't be afraid to leave them in the garden as long as possible.

To harvest, simply snap or cut the leaves off near the base of the plant. Avoid damaging the central stem. Continuous harvesting encourages more leaf production.

As the first frost approaches in late October, you can cover your plants with a blanket or row cover to extend the harvest a bit longer. Even if the leaves get a little frost-bitten, they're often still edible and taste great after cooking.

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

Cabbage Worms

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

Aphids

• What it looks like: Clusters of tiny insects (green, black, or white) on stems and leaf undersides. You might also see sticky honeydew and curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects. Populations can explode in warm weather. Ants sometimes "farm" them for honeydew.
• How to fix/prevent it: A strong spray of water can knock them off. Encourage ladybugs and lacewings. Insecticidal soap works for heavy infestations. Avoid excess nitrogen fertilizer.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, these are pale green caterpillars that move in a looping motion. They also chew holes in leaves.
• What causes it: Another type of caterpillar that feeds on brassicas.
• How to fix/prevent it: Bt spray is effective. Handpicking is also an option. Row covers can help prevent them from reaching your plants.

Downy Mildew

• What it looks like: Yellow patches on leaf tops with fuzzy gray-purple growth on undersides. Leaves brown and die from the bottom up.
• What causes it: A pathogen 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, never overhead. Copper-based fungicides can help prevent it.

Great Plains Specific Challenges: Our region's hot summers, low-to-moderate humidity, and variable rainfall can stress collard greens. The key is to provide consistent moisture without overwatering and to monitor plants regularly for pests and diseases. Wind protection is also essential to prevent damage to the leaves.

Companion planting can be a great way to improve the health and productivity of your collard greens.

Good companions:

• Onion and Garlic: These help repel pests like aphids and cabbage moths. Their strong scent confuses insects.
• Beets: They don't compete for the same nutrients and can help improve soil structure.
• Potatoes: They don't compete for the same nutrients and can help break up the soil.
• Dill: Attracts beneficial insects like ladybugs and lacewings, which prey on aphids and other pests.

Bad companions:

• Strawberry: Collard greens can inhibit the growth of strawberries.
• Tomato: Both plants are susceptible to similar pests and diseases, which can increase the risk of infestation or infection.