Collard Greens in Zone 6B — Mountain West

Collard greens are a fantastic addition to any Mountain West garden. Their slightly bitter, earthy flavor is delicious braised, sautéed, or even added raw to salads. Plus, they're incredibly versatile in the kitchen and a nutritional powerhouse. The cool nights even in summer we often experience here seem to enhance the flavor of brassicas like collards, making them even sweeter after a light frost.

Our high altitude, intense sun, and alkaline soil present unique challenges, but with careful timing, you can absolutely grow a bountiful crop of collard greens. Our short season of around 163 days means planning is key, but knowing your microclimate and taking advantage of our intense sunlight will set you up for success.

Starting collard greens indoors gives you a head start, especially with our short growing season. Sow seeds indoors from late March through mid April, 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 – bottom watering works wonders to prevent damping off – and provide plenty of light. A sunny windowsill might do, but a grow light ensures strong, healthy seedlings. Remember, our spring weather can be unpredictable, so indoor starting gives you more control.

Transplant your collard green seedlings outdoors from late April through late May, after the danger of a hard freeze has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense sun and cool nights of our Mountain climate.

Plant them 18-24 inches apart in well-draining soil. Even though our last frost is around late April, be prepared to cover your transplants if a cold snap threatens.

Direct sowing collard greens is also a viable option in the Mountain West, especially if you're looking for a less intensive approach. Sow seeds directly into the garden from mid April through early July. Ensure the soil temperature is at least 60°F for good germination.

Prepare the soil well, amending it with compost to improve drainage and fertility. Plant seeds about ½ inch deep and thin seedlings to 18-24 inches apart once they emerge. Direct sowing is convenient, but remember that young seedlings are more vulnerable to pests and temperature swings, so keep a close eye on them.

Watering is crucial for healthy collard greens in our dry Mountain West climate. While they're more heat-tolerant than some brassicas, they still need consistent moisture, especially during our hot, dry summers. Aim to keep the soil evenly moist, but not waterlogged, for the most tender leaves.

In the spring and fall, when temperatures are cooler, you might only need to water once or twice a week, providing about 1 inch of water each time. During the peak of summer, with typical highs around 85°F and almost no humidity, you'll likely need to water every other day, or even daily, providing 1-2 inches of water. Use the "finger test" – stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water.

Water at the base of the plants rather than overhead to minimize fungal diseases, especially in the cooler evenings. Signs of underwatering include wilting and yellowing leaves, while overwatering can lead to root rot and stunted growth. A good layer of mulch, like straw or wood chips, will help retain moisture and regulate soil temperature, crucial with our intense sun and cool nights.

You can expect your first harvest of collard greens from late June through mid October, depending on when you planted. Collard greens are ready to harvest when the lower leaves are about 10-12 inches long. These will typically be about 75 days from sowing.

To harvest, simply snap off the outer, lower leaves, leaving the top rosette intact. This allows the plant to continue producing new leaves throughout the season. The flavor of collard greens actually sweetens after a frost, so don't be afraid to leave them in the garden as late as possible.

As our first frost approaches in early October, harvest any remaining large leaves. You can blanch and freeze them for later use, or enjoy them in a hearty fall stew. Even after a light frost, the remaining leaves are often still delicious.

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

Cabbage Worms

• What it looks like: Smooth green caterpillars on brassica leaves. Irregular holes chewed in leaves. Dark green droppings. White butterflies hovering around plants.
• What causes it: Larvae of white cabbage butterflies. Multiple generations can occur during our relatively short warm season.
• How to fix/prevent it: Bt spray is very effective. Floating row covers prevent egg laying. Handpick caterpillars. Interplant with aromatic herbs like thyme and sage. Encourage parasitic wasps.

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Rapid-reproducing sap-sucking insects. Populations can explode during warm spells. Ant colonies may farm them for honeydew.
• How to fix/prevent it: Strong water spray knocks them off. Encourage ladybugs and lacewings (natural predators). Insecticidal soap for heavy infestations. Neem oil works systemically. Avoid excess nitrogen fertilizer, which attracts them.

Cabbage Loopers

• What it looks like: Pale green caterpillars that move in a looping motion. They chew large holes in leaves, often leaving only the veins.
• What causes it: Larvae of a grayish-brown moth. They thrive in warm weather and can quickly defoliate plants.
• How to fix/prevent it: Handpicking is effective for small infestations. Bt spray is a good option for larger outbreaks. Floating row covers can prevent moths from laying eggs on 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: Oomycete 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 adequately. Water at the base, never overhead. Copper-based fungicides can be used for prevention.

Mountain West Specific Challenges: Our moderate-at-altitude heat, low humidity, and dry rainfall can actually work to your advantage when growing collard greens. The dry conditions help reduce the risk of fungal diseases, but you'll need to be diligent about watering. Also, our intense sun can sometimes scorch leaves, so providing some afternoon shade can be beneficial, especially for young plants.

Companion planting can help your collard greens thrive in the Mountain West.

Good companions include onions and garlic, whose strong scent deters many pests that bother collards. Beets improve the soil structure and add nutrients. Potatoes don't directly benefit the collards, but they don't compete for the same nutrients and can be grown in close proximity. Dill attracts beneficial insects like ladybugs and lacewings, which prey on aphids and other pests.

Avoid planting strawberries and tomatoes near your collard greens. Strawberries are susceptible to diseases that can also affect brassicas, and tomatoes compete for the same nutrients in the soil.