Collard Greens in Zone 8B — Pacific Northwest

Collard greens are a fantastic addition to any Pacific Northwest garden. Their slightly bitter, earthy flavor mellows beautifully with cooking, and they're incredibly versatile – think Southern-style braising, vibrant salads, or even adding a nutritional boost to smoothies. Plus, their tolerance for cool nights and our long, mild fall means you can harvest fresh greens well into autumn.

While we might struggle with heat-loving plants sometimes, collards thrive in our 210-day growing season. With a little attention to timing, you can easily enjoy a bountiful harvest of these nutritious greens.

Starting collard greens indoors isn’t strictly necessary in our mild climate, but it can give you a jump start, especially if you're eager for an early harvest. If you want to start indoors, aim for early to late March, about four weeks before you plan to transplant them outside.

Use seed trays or small pots filled with seed-starting mix. Keep them in a warm spot, ideally around 70°F, and provide plenty of light – a grow light is helpful, especially during our overcast spring days. Bottom watering helps prevent damping off; simply set the tray in a shallow dish of water until the soil surface is moist.

Transplant your collard green seedlings outdoors from early April through early May, after they've developed a few sets of true leaves. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week.

Choose a spot with full sun to partial shade and space the plants 18-24 inches apart. Keep an eye on the weather forecast; if there's an unexpected cold snap, cover the seedlings with row covers or cloches.

Direct sowing collard greens is a simple and effective method, especially for later harvests. Sow seeds late March through early August, ensuring the soil temperature is at least 60°F.

Prepare the soil by loosening it and mixing in some compost. Plant seeds about ½ inch deep and space them 18-24 inches apart. Keep the soil consistently moist until the seedlings emerge. Thin to one plant per space once they have a few true leaves.

Collard greens need consistent moisture to produce tender, flavorful leaves. In our Pacific Northwest climate, this means paying close attention, especially during our dry summer months.

During the wet springs, you might not need to water much at all, but once the dry season hits, check the soil regularly. Stick your finger about two inches deep; if it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation.

Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our sometimes-humid conditions. Wilting leaves indicate underwatering, while yellowing leaves can signal overwatering. A layer of mulch, like straw or compost, helps retain moisture and suppress weeds.

You can expect your first harvest of collard greens from early June through early November, about 75 days after planting. The best time to harvest is when the lower leaves are 10-12 inches long and a healthy green color.

Harvest by cutting the outer leaves near the base of the plant, leaving the central rosette to continue growing. This allows for continuous production throughout the season. The flavor of collard greens often sweetens after a light frost, so don't be afraid to leave them in the garden a bit longer as fall approaches.

Here are a few common problems you might encounter with collard greens in the Pacific Northwest:

Cabbage Worms

• What it looks like: Smooth green caterpillars chewing irregular holes in leaves. You might also see dark green droppings and white butterflies fluttering around.
• What causes it: The larvae of white cabbage butterflies. They can have multiple generations throughout the growing season.
• How to fix/prevent it: Use Bt spray, which is very effective. Floating row covers can prevent butterflies from laying eggs. You can also handpick the caterpillars.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. Sticky honeydew residue and curled or distorted new growth.
• What causes it: Rapidly reproducing sap-sucking insects.
• How to fix/prevent it: A strong spray of water can knock them off. Encourage ladybugs and lacewings. Use insecticidal soap for heavy infestations.

Cabbage Loopers

• What it looks like: Pale green caterpillars that move in a looping motion. They chew large, ragged holes in leaves.
• What causes it: Similar to cabbage worms, they are the larvae of moths.
• How to fix/prevent it: Handpicking, Bt spray, and row covers are all effective control methods.

Downy Mildew

• What it looks like: Yellow patches on the tops of leaves with fuzzy gray-purple growth on the undersides. Leaves brown and die from the bottom up.
• What causes it: An oomycete pathogen that thrives in cool, humid conditions.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation by spacing plants properly. Water at the base, avoiding overhead watering. Copper-based fungicides can be used for prevention.

Pacific Northwest Specific Challenges: Our mild summers and dry-summer rainfall can actually be beneficial for collard greens, reducing the risk of some fungal diseases. However, late blight can still be a concern. Good air circulation and avoiding overhead watering are key. Slugs can also be a nuisance, especially in wet springs, so use appropriate control measures.

Companion planting can help your collard greens thrive. Onions and garlic are good companions because their strong scent deters many pests. Beets and potatoes are also beneficial, as they don't compete for the same nutrients. Dill attracts beneficial insects that prey on aphids and other pests.

Avoid planting collard greens near strawberries or tomatoes. Strawberries can attract slugs, which will also feast on your collards. Tomatoes can stunt the growth of collards.