Collard Greens in Zone 4A — Midwest

Collard greens are a fantastic addition to any Midwest garden. Their slightly bitter, earthy flavor is delicious in soups, stews, or even sautéed as a side dish. Plus, they tolerate our summer heat spells better than many other leafy greens, and their flavor actually sweetens up after a frost, extending your harvest well into the fall.

While Midwest weather can be unpredictable, especially in spring with its temperature swings, collards are surprisingly resilient. With a growing season of around 128 days, you have plenty of time to get a good crop. Proper timing and a little attention is all it takes.

Starting collard greens indoors gives you a head start, but it's not strictly necessary here in the Midwest. If you're itching to get going early or want to ensure a longer harvest, start seeds indoors from early April through early May, about four weeks before you plan to transplant.

Use seed trays or small pots filled with a good seed-starting mix. Keep them warm (around 70-75°F) and provide plenty of light – a grow light works best. Water gently, and consider bottom watering to avoid damping off. Our moderate-to-late springs can still bring cool snaps, so indoor starting provides a buffer.

Transplant your collard green seedlings outdoors from mid May through mid June, after the risk of a hard frost has passed. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Midwest weather.

Space the plants 18-24 inches apart in rows. Be mindful of late frosts, which are not uncommon in the Midwest even in late May. Have row covers ready to protect your young plants if needed.

Direct sowing collard greens is a straightforward option, especially if you're not in a rush. Sow seeds directly into the garden from early May through late June. This avoids transplant shock and simplifies the process.

Prepare the soil by loosening it and mixing in some compost. Make sure the soil temperature is at least 60°F for good germination. Plant seeds about ½ inch deep and space them 18-24 inches apart. You might need to thin them later if too many germinate.

Consistent watering is key to growing healthy collard greens in the Midwest. While they're more heat-tolerant than some brassicas, they still need regular moisture, especially during our summer heat spells. Aim for even moisture to promote tender, flavorful leaves.

During the wet-summer season, check the soil moisture regularly. Stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. Generally, collard greens need about 1-1.5 inches of water per week, including rainfall. Water at the base of the plants rather than overhead to reduce the risk of fungal diseases, which can be a concern with our moderate-to-humid conditions.

Yellowing leaves can indicate overwatering, while wilting leaves signal underwatering. Add a layer of mulch around your collard greens to help retain moisture and suppress weeds. Straw or shredded leaves work well in our climate.

You can expect your first harvest of collard greens from mid July through late September, depending on when you planted. The leaves are ready to harvest when they are 10-12 inches long.

Harvest the lower leaves first, leaving the top rosette to continue growing. This allows for continuous production throughout the season. Simply snap or cut the leaves off near the base of the plant. Don't be afraid to harvest frequently – this encourages new growth.

As the first frost approaches in mid- September, don't panic! Collard greens actually taste sweeter after a frost. You can continue harvesting as long as the leaves are still in good condition. If a hard freeze is predicted, you can cover the plants with a blanket or row cover to extend the harvest a bit longer.

Here are some common problems you might encounter growing collard greens in the Midwest:

Cabbage Worms

• What it looks like: Smooth green caterpillars chewing irregular holes in leaves. You might also see dark green droppings and white cabbage butterflies fluttering around.
• What causes it: These are the larvae of white cabbage butterflies, and they can have multiple generations during our warm summers.
• How to fix/prevent it: Bt spray is very effective. Use floating row covers to prevent butterflies from laying eggs. Handpick caterpillars when you see them. Consider interplanting with aromatic herbs like thyme and sage.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. You might also notice sticky honeydew and curled or distorted new growth.
• What causes it: Aphids are sap-sucking insects that reproduce rapidly, especially in warm weather.
• How to fix/prevent it: A strong spray of water can knock 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 motion. They chew large holes in leaves.
• What causes it: Cabbage loopers are another type of caterpillar that thrives in warm weather.
• How to fix/prevent it: Use Bt spray, handpick caterpillars, and use row covers.

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: This is a fungal disease that spreads in cool, humid conditions via wind-carried spores.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation. Water at the base, never overhead. Copper-based fungicides can help prevent it.

Midwest Specific Challenges: Our moderate-to-hot summers and moderate-to-humid conditions can create a favorable environment for pests and diseases. Regular monitoring and proactive measures are key to keeping your collard greens healthy. Clay soil can also be an issue; amend it with compost to improve drainage and fertility.

Companion planting can benefit your collard greens in the Midwest garden.

Good companions include onions and garlic, which deter pests with their strong scent. Beets and potatoes are also good neighbors, as they don't compete for the same nutrients. Dill attracts beneficial insects that prey on pests.

Avoid planting collard greens near strawberries or tomatoes. Strawberries are susceptible to similar fungal diseases, and tomatoes can attract pests that also bother collards.