Collard Greens in Zone 7A — Northeast

Collard greens are a Southern staple that surprisingly thrive in our Northeast gardens. Their slightly bitter, earthy flavor is fantastic braised, sauteed, or even added raw to salads. Plus, they're incredibly versatile and cold-hardy, making them a reliable crop to extend your harvest well into fall.

Our short growing season and occasional late frosts might seem daunting, but with a little planning, you can easily enjoy a bountiful harvest of collard greens. With our 198-day growing season, you have plenty of time to get these greens established and flourishing.

Starting collard greens indoors isn't essential, but it can give you a jump start, especially if you're aiming for an early harvest. Sow seeds indoors from early to late March, about four weeks before you plan to transplant them.

Use seed trays filled with a good seed-starting mix. Keep them warm and provide plenty of light, either with a grow light or a sunny windowsill. Bottom watering is a great way to keep the soil consistently moist without overwatering. Remember our late springs often have temperature swings, so indoor growing provides a stable environment.

Transplant your collard greens seedlings outdoors from early April through early May, after the danger of a hard frost has passed. Remember to harden them off for about a week before transplanting, gradually exposing them to outdoor conditions.

Space the plants 18-24 inches apart to give them room to grow. Even in April and early May, we can get some surprising cold snaps, so be prepared to cover your seedlings if necessary.

Direct sowing collard greens is a perfectly viable option, especially if you're not in a rush for an early harvest. Sow seeds directly into the garden from late March through late July.

Make sure the soil is well-prepared and has warmed up a bit. Plant seeds 1/2 inch deep, spacing them 18-24 inches apart. Direct sowing is less work than starting indoors, but your plants might take a little longer to mature.

Collard greens need consistent moisture, especially in our Northeast climate. Aim for about 1 inch of water per week, whether from rainfall or irrigation.

The finger test is your friend: 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 encourage fungal diseases in our moderate-to-humid climate. During the hottest part of summer, you might need to water more frequently.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A good layer of mulch, like straw or shredded leaves, will help retain moisture and keep the soil cool.

You can expect your first harvest of collard greens from early June through early November, depending on when you planted them. Look for leaves that are 10-12 inches long.

Harvest the lower leaves, leaving the top rosette to continue growing. This will allow for continuous production throughout the season. The flavor of collard greens actually sweetens after a frost, so don't be afraid to leave them in the garden until late in the fall.

As our first frost approaches in late October, you can harvest the entire plant if you like, or cover it to extend the harvest a bit longer. Even a light frost won't kill them!

Here are some common problems you might encounter with collard greens in your Northeast garden:

Cabbage Worms *What it looks like:* Smooth green caterpillars munching on leaves, leaving irregular holes and dark green droppings. You might also see white cabbage butterflies fluttering around. *What causes it:* Larvae of white cabbage butterflies. They can have multiple generations throughout the growing season in our region. *How to fix/prevent it:* Bt spray is your best bet. Floating row covers are great for preventing the butterflies from laying eggs. Handpicking caterpillars is also effective. Planting thyme and sage nearby can help deter 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 are also signs. *What causes it:* Rapidly reproducing sap-sucking insects. Populations can explode during warm spells. *How to fix/prevent it:* A strong spray of water will knock them off. Encourage ladybugs and lacewings, which are natural predators. Insecticidal soap can help with heavy infestations.

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:* Larvae of a moth. *How to fix/prevent it:* Bt spray is effective. Handpick them off the plants. Floating row covers can also help.

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 from the bottom up. *What causes it:* A 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 of the plants. Copper-based fungicides can be used preventatively.

Northeast Specific Challenges: Our moderate heat and moderate-to-humid humidity can create favorable conditions for some pests and diseases, like downy mildew and aphids. Consistent monitoring and early intervention are key to keeping your collard greens healthy and productive.

Companion planting can be a great way to improve the health and productivity of your collard greens. Onions and garlic are excellent companions because their strong scent deters many pests. Beets and potatoes also make good neighbors, as they don't compete for the same nutrients. Dill attracts beneficial insects that prey on pests like aphids and cabbage worms.

Avoid planting collard greens near strawberries or tomatoes. Strawberries can attract slugs and snails, which can also damage collard greens. Tomatoes can attract pests like aphids and whiteflies, which can spread to your collard greens.