Collard Greens in Zone 5B — Great Plains

Collard greens are a fantastic addition to any Great Plains garden. They offer a unique, slightly bitter flavor that's delicious braised, sautéed, or even added to soups. Plus, their cold hardiness means you can often harvest them well into the fall, even after a light frost sweetens the leaves.

Our variable spring weather and potential for summer drought can present challenges, but with careful timing, collard greens thrive here. Our 178-day growing season gives you ample opportunity to enjoy multiple harvests of this nutritious leafy green.

Starting collard greens indoors gives you a jump start, especially if you're further north in the Plains where the growing season is shorter. You can sow seeds indoors from mid-March through early April, about four weeks before you plan to transplant.

Use seed trays with a good seed-starting mix and keep them warm and consistently moist. Bottom watering is a great way to prevent damping off. A sunny window or grow light will provide the light they need as our spring weather can be unpredictable.

Transplant your collard green seedlings outdoors from mid-April through mid-May, once the danger of hard frost has passed. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Space them 18-24 inches apart to give them plenty of room to grow. Keep an eye on the weather forecast – a late-season cold snap or hailstorm can damage young plants, so be ready to cover them if needed.

Direct sowing collard greens is a viable option in the Great Plains, especially if you're not in a rush. Sow seeds directly into well-prepared soil from early April through mid-July.

Make sure the soil temperature is at least 60°F for good germination. Plant seeds about ½ inch deep and thin seedlings to 18-24 inches apart once they emerge. Direct sowing avoids transplant shock, but you'll need to be diligent about weed control and watering, especially during the hot summer months.

Watering is key to growing healthy collard greens in our Plains climate. While they're more heat-tolerant than some other brassicas, they still need consistent moisture, especially during our hot, dry summers.

In the spring, when temperatures are cooler and rainfall is more frequent, you may only need to supplement natural rainfall once or twice a week. As the summer heat intensifies, increase watering to 1-1.5 inches per week, delivered in one or two deep soakings. Use the "finger test" – if the top 2 inches of soil feel dry, it's time to water.

Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our low-to-moderate humidity. Wilting leaves indicate underwatering, while yellowing leaves and soggy soil suggest overwatering. A good layer of mulch around your collard greens helps retain moisture and suppress weeds, which is particularly important during our dry spells.

You can expect your first harvest of collard greens from mid-June through late October, about 75 days after planting. Look for lower leaves that are 10-12 inches long and a deep green color.

Harvest by cutting or snapping off the outer leaves, leaving the central rosette to continue growing. This allows for continuous production throughout the season. The flavor of collard greens actually sweetens after a light frost, so don't be afraid to leave them in the garden as the weather cools.

As the first hard frost approaches in mid- October, harvest any remaining large leaves to enjoy. You can even cover the plants with a blanket or row cover to extend the harvest a bit longer if the weather cooperates.

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

Cabbage Worms

• What it looks like: Irregular holes chewed in leaves, smooth green caterpillars on the leaves, dark green droppings, and white butterflies fluttering around.
• What causes it: The larvae of white cabbage butterflies. They can have multiple generations in our warm summers.
• How to fix/prevent it: Use Bt spray, which is very effective. Cover plants with floating row covers to prevent butterflies from laying eggs. Handpick caterpillars when you see them. Interplant with aromatic herbs like thyme and sage to deter the butterflies.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects. Populations can explode in warm weather.
• How to fix/prevent it: Knock them off with a strong spray of water. Encourage ladybugs and lacewings, which are natural predators. Use insecticidal soap for heavy infestations. Neem oil can also work. 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: Similar to cabbage worms, these are the larvae of a moth.
• How to fix/prevent it: Use Bt spray. Handpick caterpillars. Encourage parasitic wasps. Floating row covers can also help.

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 around plants. Water at the base, never overhead. Copper-based fungicides can be used for prevention.

Great Plains Specific Challenges: Our extreme temperature swings and variable rainfall can stress collard greens, making them more susceptible to pests and diseases. Wind protection is essential to prevent leaf damage. Consistent watering is crucial, especially during hot, dry spells. Keep a close eye on your plants and act quickly to address any problems that arise.

Companion planting can greatly benefit your collard greens in the Great Plains garden. Onions and garlic help deter pests like aphids and cabbage moths with their strong scent. Beets provide minerals that can improve soil health and benefit collard greens. Potatoes also make good companions, as they don't compete for the same nutrients. Dill attracts beneficial insects like ladybugs and parasitic wasps that prey on pests.

Avoid planting collard greens near strawberries or tomatoes. Strawberries compete for nutrients, and tomatoes can attract pests that also affect collard greens. Thoughtful companion planting can create a healthier, more productive garden.