Collard Greens in Zone 6A — Pacific Northwest

Collard greens thrive in our mild Pacific Northwest summers, offering a slightly bitter, earthy flavor that's fantastic braised, sauteed, or added to soups. The cool nights here actually improve their flavor, making them sweeter and more palatable. Plus, the satisfaction of harvesting fresh greens well into fall is a real treat in our region.

While we may struggle with heat-loving plants, collards are perfectly suited to our 148-day growing season. We just need to be mindful of timing and potential pests. Starting seeds at the right time ensures a successful harvest before the first frost hits.

Starting collard greens indoors gives you a head start, especially if we have a particularly cool spring. Start your seeds indoors from early to late April, about four weeks before you plan to transplant them outside. This helps you get a jump on the season when our soil is still cool.

Use seed trays or small pots filled with seed-starting mix. Provide warmth and plenty of light, either from a sunny window or a grow light. Bottom watering is a great way to keep the soil consistently moist without overwatering, something especially useful with our overcast spring days.

Transplant your collard green seedlings outdoors from early May through early June, after the risk of hard frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This prevents transplant shock.

Space your plants 18-24 inches apart to give them plenty of room to grow. Keep an eye on the forecast; a late cold snap can still happen, so be ready to cover your young plants if necessary.

Direct sowing collard greens is a straightforward option, especially if you're looking for a low-maintenance approach. Sow seeds directly into the garden from late April through early July. This gives the plants enough time to mature before our first frost.

Prepare the soil by loosening it and adding compost. Make sure the soil temperature is at least 60°F (15°C) for optimal germination. Thin seedlings to 18-24 inches apart once they emerge.

Collard greens need consistent moisture, especially during our dry summer months. Aim for about 1 inch of water per week, either from rainfall or irrigation. Use the "finger test" – stick your finger about 2 inches into the soil. If it feels dry, it's time to water.

Water deeply at the base of the plants rather than overhead to minimize the risk of fungal diseases, which can sometimes be a concern even with our dry-summer humidity. Watering at the base keeps the leaves dry. In the PNW, we often don't need to water as much as other regions due to our consistent rainfall, especially in the spring and fall.

Signs of underwatering include wilting leaves, while overwatering can lead to yellowing leaves and root rot. A layer of mulch around your plants will help retain moisture and suppress weeds.

You can expect your first harvest of collard greens from early July through mid October, about 75 days after planting. Harvest the lower leaves when they are 10-12 inches long. Leave the top rosette intact to continue producing new leaves.

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. Harvest leaves as needed, working from the bottom up. As the first frost approaches in early October, harvest any remaining large leaves to prevent them from being damaged by the cold.

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

Cabbage Worms

• What it looks like: Smooth green caterpillars chew irregular holes in leaves, leaving dark green droppings behind. You might also see white butterflies fluttering around your plants.
• What causes it: These are the larvae of white cabbage butterflies. They can have multiple generations in a season if conditions are warm enough, though our mild summers usually limit their numbers.
• How to fix/prevent it: Bt spray is very effective against cabbage worms. Floating row covers will prevent the butterflies from laying eggs on your plants. You can also handpick the caterpillars and interplant 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: Aphids are sap-sucking insects that reproduce rapidly, especially in warm weather. Ant colonies may farm them for the honeydew they produce.
• How to fix/prevent it: A strong spray of water can knock aphids off your plants. Encourage ladybugs and lacewings, which are natural predators. Insecticidal soap can be used for heavy infestations, and neem oil works systemically. Avoid excess nitrogen fertilizer, as it attracts them.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, these are pale green caterpillars that move in a looping motion. They also chew holes in leaves.
• What causes it: These are the larvae of moths. Like cabbage worms, they thrive in warmer conditions.
• How to fix/prevent it: Use Bt spray, handpick the caterpillars, and use floating row covers to prevent moths from laying eggs.

Downy Mildew

• What it looks like: Yellow patches on leaf tops with fuzzy gray-purple growth on the undersides. Leaves brown and die from the bottom up.
• What causes it: This is a disease that spreads in cool, humid conditions via wind-carried spores.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation around your plants by spacing them properly. Water at the base, never overhead. Copper-based fungicides can be used for prevention.

Pacific Northwest Specific Challenges: Our mild heat and dry-summer rainfall can actually help reduce some pest and disease pressures on collard greens compared to other regions. However, slugs can still be a problem, especially in wet springs. Use slug bait or traps to protect your plants.

Companion planting can really benefit your collard greens. Onions and garlic are great companions because their strong scent deters many pests. Beets and potatoes are also good choices 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 are susceptible to diseases that can also affect collards, and tomatoes can attract pests that will also feed on your greens.