Collard Greens in Zone 5A — Mountain West

Collard greens thrive in our cool Mountain West nights, which actually sweeten their flavor. They're incredibly versatile, lending themselves to Southern-style braising or a quick sauté. Plus, harvesting your own greens, even in our challenging climate, is deeply satisfying.

High altitude gardening presents unique hurdles: intense sun, alkaline soil, and a short growing season of about 138 days. But with careful timing and attention, you can absolutely enjoy homegrown collards. Our moderate summer heat and intense sunlight can actually be an advantage.

Starting collard greens indoors is an option, especially if you want a head start on our short season. Sow seeds early to late April, about four weeks before your anticipated transplant date. This gives you a jump, considering our springs can be late.

Use seed trays with a good seed-starting mix. Keep them warm (around 70°F) and provide plenty of light – a grow light is ideal. Bottom watering helps prevent damping-off, a common problem with seedlings.

Transplant your collard greens outdoors early May through early June, after hardening them off. This means gradually exposing them to outdoor conditions for about a week. Start with a few hours of shade and increase the sun exposure each day.

Space the plants 18-24 inches apart. Keep an eye on the weather; late frosts can still happen in early May, so be ready to cover your seedlings if needed.

Direct sowing collard greens is perfectly doable in our Mountain climate. Sow seeds late April through late June, once the soil has warmed up a bit.

Prepare the soil well, ensuring it's loose and fertile. Plant seeds about ½ inch deep, spacing them according to package directions, then thin to 18-24 inches apart. Direct sowing is less work, but you'll need to be diligent about watering and weeding.

Collard greens need consistent moisture, especially in our dry Mountain West climate. Aim for about 1-1.5 inches of water per week, especially during hot spells. Don't let them dry out completely, or the leaves will become tough.

Stick your finger about two inches deep into the soil. If it feels dry, it's time to water. Water deeply at the base of the plants, avoiding overhead watering which can encourage fungal diseases in some areas, though our low humidity helps minimize this risk.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch, such as straw or wood chips, helps retain moisture and regulate soil temperature.

You can expect your first harvest of collard greens early July through early October, about 75 days after planting. Look for the lower leaves to be 10-12 inches long and a good, dark green color.

Harvest by cutting the outer leaves, 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, a benefit of our cool nights.

As the first frost approaches in late September, harvest any remaining large leaves. You can also cover the plants with a blanket or row cover for a few extra weeks of harvest.

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

Cabbage Worms

• What it looks like: Smooth green caterpillars chewing irregular holes in leaves. You might also see dark green droppings and white cabbage butterflies fluttering around.
• What causes it: Larvae of cabbage butterflies. They can have multiple generations, even in our relatively short season.
• How to fix/prevent it: Bt spray is effective. Floating row covers prevent butterflies from laying eggs. Handpick caterpillars when you see them.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and undersides of leaves. Sticky honeydew residue and curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects. They can boom quickly, even with our low humidity.
• How to fix/prevent it: A strong spray of water can knock them off. Encourage ladybugs and lacewings. Use insecticidal soap if the infestation is heavy.

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: Another type of moth larvae.
• How to fix/prevent it: Same as for cabbage worms: Bt spray, row covers, handpicking.

Downy Mildew

• What it looks like: Yellow patches on the upper leaf surface with fuzzy gray-purple growth on the undersides. Leaves eventually brown and die, starting from the bottom.
• What causes it: A pathogen that thrives in cool, humid conditions. While we're generally dry, cool nights can still create enough humidity for it to spread.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation around plants. Water at the base. Copper-based fungicides can help prevent it.

Mountain West Specific Challenges: Our intense sun can sometimes scorch leaves, especially on young plants. Providing some afternoon shade can help. Alkaline soil can also be an issue; amend with compost to improve soil pH. Hail can be devastating; consider using netting for protection.

Companion planting can really help your collard greens thrive. Onions and garlic are great companions because their strong scent deters many pests. Beets also work well, as they don't compete for the same nutrients and can help loosen the soil. Potatoes are beneficial because they attract beneficial insects that prey on collard green pests. Dill attracts beneficial insects that prey on aphids and cabbage worms.

Avoid planting strawberries or tomatoes near your collard greens. Strawberries can attract slugs and snails that may also attack your greens. Tomatoes can stunt the growth of collard greens, as they compete for similar nutrients in the soil.