Collard Greens in Zone 3B — Great Plains

Collard greens thrive in our Plains summers and provide a delicious, slightly bitter flavor that's fantastic braised, sautéed, or added to soups. Their sturdy texture holds up well in the heat, and they offer a welcome green to your table even as other plants are struggling. Plus, there's real satisfaction in harvesting your own greens after a long winter.

Our weather here can be unpredictable, with extreme temperature swings and the occasional hail. But with a little planning and attention to timing, you can definitely enjoy a successful collard crop within our roughly 118-day growing season.

Starting collards indoors gives you a jump on the season, especially if you're farther north in the Plains. You can start seeds indoors from mid-April through early May, about four weeks before you plan to transplant them outside. This is especially helpful if spring is slow to warm up.

Use seed trays or small pots filled with a good seed-starting mix. Keep them warm (around 70°F) and provide plenty of light – a grow light works great. Don't forget to water from the bottom to prevent damping off.

The variable spring weather on the Plains can make indoor starting a good strategy for a more reliable harvest.

Transplant your collard seedlings outdoors from mid-May through mid-June, once the risk of a hard frost has passed. Be sure to harden them off for about a week before transplanting. Gradually expose them to outdoor conditions to prevent shock.

Space the plants 18-24 inches apart to give them plenty of room to grow. The Plains can still have some chilly nights even in late May, so keep an eye on the forecast and be prepared to cover them if necessary.

Direct sowing is a perfectly viable option for collards here on the Plains, especially if you're looking for a more hands-off approach. Sow the seeds directly into the garden from early May through mid-June.

Make sure the soil is warm (at least 60°F) for good germination. Prepare the soil well, loosening it and adding compost. Plant seeds about ½ inch deep and space them 18-24 inches apart. Thin seedlings as needed. Direct sowing can be a bit riskier with our variable spring weather, but it saves time and effort.

Collard greens need consistent moisture to produce tender, flavorful leaves, but they don't like to be waterlogged. Here on the Plains, that can be a tricky balance with our hot summers and variable rainfall.

During the hotter parts of summer (typical high: 93°F), you'll likely need to water deeply about twice a week, providing roughly 1-1.5 inches of water each time. Use the finger test: stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. In spring and fall, when temperatures are milder and rainfall is more frequent, you may only need to water once a week, or even less.

Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our low-to-moderate humidity. Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch can help conserve moisture and regulate soil temperature, which is especially helpful during our extreme temperature swings.

You can expect to start harvesting your collard greens from mid-July through late September, about 75 days after planting. The best time to harvest is when the lower leaves are about 10-12 inches long.

Harvest by cutting or snapping off the outer leaves, leaving the top rosette to continue growing. This allows for continuous production throughout the season. Collard greens actually taste sweeter after a light frost, so don't be afraid to leave them in the garden until mid-September.

As the first frost approaches, harvest any remaining large leaves. You can blanch and freeze them for later use, or add them to soups and stews.

Even with our relatively low disease pressure here on the Plains, collard greens can still face a few challenges.

Cabbage Worms

• What it looks like: Smooth green caterpillars on brassica leaves with irregular holes chewed in leaves. You might also see dark green droppings and white butterflies hovering around your plants.
• What causes it: These are the larvae of white cabbage butterflies. They can have multiple generations per season if the weather stays warm enough.
• How to fix/prevent it: Bt spray is very effective and safe to use. Floating row covers are great for keeping the butterflies from laying eggs. You can also handpick the caterpillars and interplant with aromatic herbs like thyme and sage to deter the butterflies. Encourage parasitic wasps, which are natural predators.

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) 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 sometimes "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, and neem oil can be used systemically. Avoid excess nitrogen fertilizer, as it attracts aphids.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but these caterpillars move in a looping motion. They chew large holes in leaves.
• What causes it: These are the larvae of a different type of moth.
• How to fix/prevent it: The same methods used for cabbage worms will work for cabbage loopers: Bt spray, handpicking, and row covers.

Downy Mildew

• What it looks like: Yellow patches on leaf tops with fuzzy gray-purple growth on the undersides. Leaves brown and die from the bottom up.
• What causes it: This is an oomycete pathogen that spreads in cool, humid conditions via wind-carried spores.
• How to fix/prevent it: Remove affected leaves immediately and improve air circulation around your plants. Water at the base, never overhead. Copper-based fungicides can be used for prevention. Plant resistant varieties if available.

Great Plains Specific Challenges: The hot, dry summers on the Plains can stress collard greens, making them more susceptible to pests and diseases. Variable rainfall can also make it difficult to maintain consistent moisture levels. Be sure to monitor your plants closely and adjust your watering and pest control strategies as needed. Wind protection is essential to keep the plants from drying out.

Companion planting can be really helpful on the Plains, especially to maximize your limited space and protect against pests.

Good companions for collard greens include onions and garlic, which deter many pests with their strong scent. Beets and potatoes are also good neighbors, as they don't compete for the same nutrients. Dill attracts beneficial insects like ladybugs and lacewings, which prey on aphids and other pests.

Avoid planting collard greens near strawberries or tomatoes. Strawberries can attract slugs and snails, which may also feed on your collards. Tomatoes are susceptible to diseases that can also affect collards.