Collard Greens in Zone 6B — Pacific Northwest

Collard greens thrive in our mild summers and even taste better after a touch of frost, making them a perfect fit for the Pacific Northwest garden. Their versatility in the kitchen, from Southern-style braising to adding a nutritious boost to stir-fries, makes them a rewarding crop to grow right here in your backyard.

While our overcast spring days and the potential for late blight can present challenges, with careful timing and attention, you can easily enjoy a bountiful harvest of collard greens within our 162-day growing season. You'll find that these leafy greens are well-suited to our climate, offering a reliable and flavorful addition to your meals.

Starting collard greens indoors is an option, particularly if you're eager to get a head start on the season. Sow seeds indoors from late March through mid April, about four weeks before you plan to transplant them outside. Use seed trays with a good seed-starting mix and provide consistent warmth and light.

Bottom watering is your friend during this stage; it helps prevent damping-off and keeps the seedlings evenly moist. Given our slow-starting springs, indoor starts can give your collards a jump on the season, but direct sowing often works just as well here.

Transplant your collard greens seedlings outdoors from early to late May, after the danger of hard frost has passed. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the cooler temperatures and stronger sunlight.

Space your plants 18-24 inches apart to allow them plenty of room to grow. Keep an eye on the weather forecast – a late cold snap is not unheard of here, so be ready to cover your young plants if needed.

Direct sowing is a perfectly viable method for growing collard greens in the Pacific Northwest. Sow seeds directly into the garden from mid April through mid July. This gives you a long window to get them established.

Prepare your soil by loosening it and amending with compost. Ensure the soil temperature is at least 50°F for good germination. Space seeds 18-24 inches apart or sow them closer and thin later. Direct sowing skips the transplanting stress and can result in strong, healthy plants.

Collard greens need consistent moisture to produce tender, flavorful leaves, but overwatering can be just as detrimental, especially with our wet springs. Aim to keep the soil evenly moist, but not soggy. During our dry summer months, you'll need to pay closer attention to watering.

Check the soil moisture by using the "finger test"—stick your finger about two inches deep into the soil. If it feels dry, it's time to water. In general, aim for about 1 inch of water per week, either through rainfall or irrigation. Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our climate.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around your plants can help retain moisture and suppress weeds, which is especially helpful during our drier summer months.

You can expect your first harvest of collard greens from early July through mid October, about 75 days after planting. Look for lower leaves that are 10-12 inches long and a deep green color. These are ready to be harvested.

Harvest by cutting the outer leaves near the base of the plant, leaving the top rosette to continue growing. This encourages continued production throughout the season. Collard greens actually taste sweeter after a light frost, so don't be afraid to leave them in the garden as the weather cools.

As the first frost approaches in early October, you can harvest the entire plant if you prefer, or cover it with a frost blanket to extend the harvest a bit longer. Fresh collard greens are best enjoyed soon after harvesting.

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

Cabbage Worms

• What it looks like: You'll see smooth, green caterpillars munching on leaves, leaving irregular holes and dark green droppings. White butterflies fluttering around are a giveaway.
• What causes it: These are the larvae of those white cabbage butterflies. They can have multiple generations during our warmer months.
• How to fix/prevent it: Bt spray is very effective. Floating row covers prevent butterflies from laying eggs. Handpicking works too. Try interplanting with aromatic herbs like thyme and sage to deter them.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. You might also notice sticky honeydew residue and curled or distorted new growth.
• What causes it: These sap-sucking insects reproduce rapidly, especially when it warms up. Ants often "farm" them for their honeydew.
• How to fix/prevent it: A strong blast of water from the hose knocks them off. Encourage ladybugs and lacewings, which are natural predators. Insecticidal soap works well for heavy infestations.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but these caterpillars move in a looping fashion. They chew large holes in leaves, often leaving only the veins.
• What causes it: Cabbage loopers are another type of caterpillar that thrives in warm weather. They are often more prevalent later in the season.
• How to fix/prevent it: Use Bt spray, handpick them off the plants, and use floating row covers to prevent the moths from laying eggs.

Downy Mildew

• What it looks like: Yellow patches on the tops of leaves with fuzzy, gray-purple growth on the undersides. Leaves will eventually brown and die, starting from the bottom of the plant.
• What causes it: This is a fungal disease that spreads in cool, humid conditions. It's more common during our wet springs and falls.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation around your plants. Water at the base, avoiding overhead watering. Copper-based fungicides can help prevent its spread.

Pacific Northwest Specific Challenges: Our mild summers and dry-summer rainfall can actually help reduce some pest and disease pressures on collard greens compared to other regions. However, our wet springs and the risk of late blight in the area mean you need to be vigilant about air circulation and avoiding overhead watering. Slugs can also be an issue, especially for young plants, so use appropriate control methods if they become a problem.

Good companions for collard greens include onions and garlic, whose strong scent can deter pests like cabbage moths. Beets and potatoes also make good neighbors, as they don't compete for the same nutrients. Dill is another beneficial companion, attracting beneficial insects that prey on aphids and other pests.

Avoid planting collard greens near strawberries or tomatoes. Strawberries can attract slugs, which will then target your collards. Tomatoes can harbor diseases that might also affect your collard greens. Companion planting is a great way to maximize your garden space and create a healthier ecosystem, especially in our unique Pacific Northwest climate.