Collard Greens in Zone 4A — Mountain West

Collard greens might not be the first thing you think of for high-altitude gardening, but these hardy greens thrive in our cool nights and intense sunlight. The slight bitterness mellows with a touch of frost, making them a delicious and nutritious addition to your Mountain garden. They’re incredibly versatile – sauté them, add them to soups, or even use them as wraps.

Our short season and alkaline soil can be a challenge, but with careful timing, collards are absolutely achievable. With a growing season of around 118 days, you'll have plenty of time to enjoy a harvest. We'll walk you through the best strategies to make it happen.

Starting collard greens indoors is an option, but honestly, with our short season, direct sowing often works just as well, if not better. If you want a head start, begin around mid-April through early May, about four weeks before you plan to transplant.

Use seed trays with a good seed-starting mix, and keep them in a warm spot, ideally around 70°F. A heat mat can help. Make sure they get plenty of light – a grow light is best, especially with our late spring starts. Bottom watering is key to prevent damping off.

Remember, our spring weather can be unpredictable. Indoor starting gives you a buffer if we get a late cold snap.

Transplant your collard green seedlings outdoors from mid-May through mid-June, once the danger of a hard frost has passed. Before you transplant, harden them off for about a week. Gradually expose them to outdoor conditions, starting with an hour or two of shade and increasing the time and sun exposure each day.

Space your plants 18-24 inches apart to give them room to grow. Even in late May, keep an eye on the forecast for any unexpected cold snaps. A row cover can provide extra protection if needed.

Direct sowing collard greens is a great option for Mountain gardeners. Sow seeds directly into the garden from early May through mid-June. Make sure the soil temperature is at least 60°F for good germination.

Prepare your soil by amending it with compost to improve drainage and nutrient content. Sow seeds about ½ inch deep and space them 18-24 inches apart. Thin seedlings as they emerge to ensure proper spacing. Direct sowing avoids transplant shock, which can be beneficial in our short growing season.

Watering is crucial for collard greens, especially in our dry Mountain climate. While they're more heat-tolerant than some other brassicas, consistent moisture is key for tender, flavorful leaves.

In the spring, when temperatures are cooler, water deeply once a week, providing about 1 inch of water. As the summer heat ramps up (relatively speaking – we're still talking about highs around 85°F), increase watering to 1-2 inches per week. Use the "finger test" – stick your finger about 2 inches into the soil. If it feels dry, it's time to water.

Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases, even in our low-humidity environment. Signs of underwatering include wilting leaves, while overwatering can lead to yellowing and root rot. A layer of mulch, like straw or wood chips, helps retain moisture and regulate soil temperature.

You can expect your first harvest of collard greens from mid-July through late September. Collards are ready to harvest about 75 days after planting.

Harvest the lower leaves when they are 10-12 inches long, leaving the top 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 long as possible.

As our first frost approaches around mid-September, harvest as many leaves as you can. While collards are frost-hardy, a hard freeze can damage them. You can also cover your plants with a row cover for some added protection.

Here are a few common problems you might encounter with collard greens in the Mountain West:

Cabbage Worms *What it looks like:* Smooth green caterpillars on leaves, irregular holes, dark green droppings, white butterflies. *What causes it:* Larvae of white cabbage butterflies. We can get multiple generations in our moderate summer climate. *How to fix/prevent it:* Bt spray is effective. Floating row covers prevent egg laying. Handpick caterpillars. Interplant with aromatic herbs.

Aphids *What it looks like:* Clusters of tiny insects on stems and leaf undersides, sticky residue, curled growth. *What causes it:* Rapid-reproducing sap-sucking insects. Populations can explode even in our warm weather. *How to fix/prevent it:* Strong water spray knocks them off. Encourage ladybugs. Insecticidal soap for heavy infestations.

Cabbage Loopers *What it looks like:* Similar to cabbage worms but move in a looping motion. Chew large holes in leaves. *What causes it:* Another type of caterpillar pest, more tolerant of warm temperatures than cabbage worms. *How to fix/prevent it:* Handpicking, Bt spray, row covers. Keep a close eye on plants and remove them as soon as you see them.

Downy Mildew *What it looks like:* Yellow patches on leaf tops, fuzzy gray-purple growth on undersides. Leaves die from the bottom up. *What causes it:* Oomycete pathogen that spreads in cool, humid conditions. More common during our cooler, wetter springs. *How to fix/prevent it:* Remove affected leaves. Improve air circulation. Water at the base. Copper-based fungicides for prevention.

Mountain West Specific Challenges: Our intense UV radiation can sometimes stress plants, making them more susceptible to pests and diseases. Keep plants well-watered and consider providing some afternoon shade during the hottest part of the summer. Alkaline soil can also be an issue, so amend with compost to lower the pH. Hail can be devastating, so consider using netting or row covers to protect your plants.

Companion planting can really help your collard greens thrive. Onions and garlic are great companions because their strong scent repels many pests that bother collards. Beets improve the soil structure and provide nutrients that collards appreciate. Potatoes can help break up heavy soil, making it easier for collard roots to grow. Dill attracts beneficial insects like ladybugs and lacewings, which prey on aphids and other pests.

Avoid planting collards near strawberries or tomatoes. Strawberries compete for nutrients, and tomatoes are susceptible to diseases that can spread to collards.