Collard Greens in Zone 3B — Mountain West

Collard greens might not be the first thing that comes to mind for high-altitude gardening, but their slightly bitter, earthy flavor is a welcome addition to our short-season harvests. They're surprisingly versatile – braise them, add them to soups, or even use them in salads when the leaves are young. Plus, there's something deeply satisfying about harvesting your own greens as the nights start to cool down.

Our short growing season and alkaline soil can be a challenge, but with a little planning, you can absolutely grow collards here in the Mountain West. With a 108-day growing season, you'll need to time your planting carefully. Luckily, collards can handle a touch of frost, giving you a bit of wiggle room.

Starting collard greens indoors is an option, though not always necessary given our short season. If you want a head start, aim to sow seeds indoors from mid-April through mid-May, about four weeks before you plan to transplant them outside. This gives the seedlings a jump before the risk of frost has passed.

Use seed trays with a good seed-starting mix and keep them in a warm location (around 70°F) with plenty of light – a south-facing window or grow lights work well. Bottom watering is key to prevent damping off; set the tray in a shallow dish of water and let the soil absorb moisture from the bottom. Remember, spring in the mountains can be unpredictable, so having seedlings ready to go gives you flexibility if the weather throws a curveball.

Once the danger of frost has passed, typically from late May through mid-June, it's time to transplant your collard greens seedlings outdoors. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense sun and cooler nights we experience.

Plant seedlings 18-24 inches apart in well-drained soil. Keep an eye on the forecast – late spring hailstorms can damage young plants, so be ready to cover them if needed. A row cover can also provide protection from pests and our intense UV rays.

Direct sowing collard greens is a viable option, especially if you're not looking for a super early harvest. Sow seeds directly into the garden from mid-May through mid-June, once the soil has warmed up. While direct sowing is less work initially, the plants will need consistent moisture to germinate.

Prepare the soil by loosening it and adding compost to improve drainage and fertility – our alkaline soil benefits from the added organic matter. Plant seeds about ½ inch deep and thin seedlings to 18-24 inches apart once they emerge. Keep the soil consistently moist, especially during germination.

Watering is crucial for collard greens in our dry Mountain West climate. While they're more heat-tolerant than some brassicas, consistent moisture is essential for tender, flavorful leaves. Aim to keep the soil evenly moist, but not waterlogged.

During the cooler spring months, you might only need to water once or twice a week, but as the temperatures rise in the summer, increase watering to 2-3 times per week, providing about 1-2 inches of water each time. 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 minimize the risk of fungal diseases in our low-humidity environment. Signs of underwatering include wilting leaves, while yellowing leaves can indicate overwatering.

Adding a layer of mulch around your collard greens, such as straw or wood chips, helps retain moisture in the soil and suppress weeds. This is especially important during our hot, dry summers.

You can expect your first harvest of collard greens from late July through mid-September, about 75 days after planting. Look for leaves that are 10-12 inches long and a deep green color. The lower, outer leaves are usually the first to mature.

To harvest, simply cut or snap off the mature leaves near the base of the plant, leaving the top rosette intact. This allows the plant to continue producing new leaves throughout the season. Regular harvesting encourages continued growth. The flavor of collard greens actually sweetens after a light frost, so don't be afraid to leave them in the garden a little longer as the weather cools.

As the first frost approaches in early September, you can harvest the entire plant if you prefer, or cover it with a frost blanket to extend the harvest for a few more weeks.

Here are some common problems you might encounter with 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 per season.
• How to fix/prevent it: Bt spray is very effective. Floating row covers prevent egg laying. Handpick caterpillars. Interplant with aromatic herbs (thyme, 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 explode in warm weather.
• 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 (it attracts them).

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but these caterpillars move with a distinctive looping motion. They chew large holes in leaves and can quickly defoliate plants.
• What causes it: The larvae of a nocturnal moth. They are most active at night.
• How to fix/prevent it: Handpick the loopers off the plants, especially in the early morning or late evening. Use Bt spray, which is effective against young loopers. Floating row covers can prevent moths from laying eggs on the 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 conditions.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation. Water at the base, never overhead. Copper-based fungicides for prevention.

Mountain West Specific Challenges: Our intense sun can sometimes stress plants, making them more susceptible to pests. While our low humidity generally reduces fungal issues, it also means we need to be diligent about watering. Hailstorms can be devastating, so consider using row covers or netting to protect your collard greens.

Companion planting can benefit your collard greens in several ways. Onions and garlic are excellent companions because their strong scent deters many pests, including aphids and cabbage moths. Beets are also good companions, as they help to loosen the soil and improve drainage, which is especially helpful in our often-compacted alkaline soil. Potatoes can provide some shade during the hottest part of the day, protecting the collard greens from our intense UV rays. 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 compete for nutrients, and tomatoes can attract pests that also affect collards.