Cabbage in Zone 6A — Midwest

Cabbage is a rewarding crop to grow in the Midwest. The crisp texture and slightly sweet flavor, especially after a touch of frost, make it a versatile addition to your kitchen. From slaws to stir-fries, it’s a garden staple that thrives with our fertile soil and good summer heat.

Midwest weather can be unpredictable, with temperature swings in spring and the occasional summer heat spell. But don't worry, with a little planning and attention to timing, you can successfully grow cabbage within our 178-day growing season.

Starting cabbage indoors gives you a head start on the season, allowing you to harvest earlier. Aim to sow your seeds from mid-February through early March, about 6 weeks before you plan to transplant them outside. This timing helps you avoid the worst of our variable spring weather.

Use seed trays or small pots filled with a good seed-starting mix. Keep the soil consistently moist, and consider bottom watering to prevent damping off. Provide warmth and plenty of light, either from a sunny window or grow lights. Starting indoors helps you get a jump on the season, especially with our moderate-to-late springs.

Transplant your cabbage seedlings outdoors in early April through early May, once the danger of hard frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Midwest weather.

Space your plants 12-18 inches apart to allow for proper head development. Be mindful of late frosts, which can still occur in early spring. If a frost is predicted, cover your young plants with row covers or blankets.

Cabbage needs consistent moisture to thrive, but overwatering can be just as detrimental as underwatering, especially with our moderate-to-humid conditions. Aim for about 1 inch of water per week, either from rainfall or irrigation. Our wet-summer rainfall can help with this.

Use the "finger test" to check soil moisture: stick your finger about 2 inches deep 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 humid climate. Signs of underwatering include wilting leaves, while yellowing leaves and stunted growth can indicate overwatering.

Mulching around your cabbage plants with straw or wood chips helps retain moisture and suppress weeds. This is especially useful during summer heat spells.

You can expect your first cabbage harvest from mid-June through early August, about 70 days after planting. The key is to watch for signs of ripeness. A ripe cabbage head will feel firm and solid when squeezed, and it will have reached its full size for the variety you're growing.

To harvest, use a sharp knife to cut the head at its base. Leave the outer leaves intact, as they can sometimes produce smaller secondary heads. As the first frost approaches in mid- October, harvest any remaining mature heads. Cabbage can tolerate a light frost, but a hard freeze can damage the heads.

Here are some common cabbage problems we face in the Midwest:

Cabbage Worms

• What it looks like: Smooth green caterpillars chewing irregular holes in leaves. You'll also see dark green droppings and white butterflies fluttering around your plants.
• What causes it: The larvae of those white cabbage butterflies. They can go through multiple generations in a single season with our warm summers.
• How to fix/prevent it: Bt spray is very effective against cabbage worms. Floating row covers will prevent the butterflies from laying eggs. You can also handpick the caterpillars or interplant cabbage with aromatic herbs like thyme or sage to deter the butterflies.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but these caterpillars move in a looping motion. They also chew holes in the leaves.
• What causes it: Cabbage loopers are another type of caterpillar that feeds on brassicas. Like cabbage worms, they thrive in our warm summer weather.
• How to fix/prevent it: Bt spray is also effective against cabbage loopers. Handpicking and row covers are other good options.

Splitting

• What it looks like: The cabbage head cracks or splits open.
• What causes it: Inconsistent watering, especially heavy watering after a dry spell. This sudden influx of water causes the head to grow too quickly, leading to splitting.
• How to fix/prevent it: Water regularly and consistently, especially during dry periods. Mulching can help maintain even soil moisture. Harvest cabbage heads as soon as they are mature to prevent splitting.

Clubroot

• What it looks like: Stunted growth, wilting in the afternoon heat, and yellowing leaves. If you dig up the plant, you'll see swollen, distorted, club-shaped roots.
• What causes it: A soil-borne pathogen (Plasmodiophora brassicae) that can persist in the soil for over 10 years. It favors acidic, wet soil.
• How to fix/prevent it: Raise the soil pH to 7.0-7.2 with lime. Improve drainage to prevent waterlogged conditions. Rotate brassicas on a 7-year cycle. Remove and destroy infected plants (don't compost them). Start transplants in a sterile mix.

Midwest Specific Challenges: Our moderate-to-hot heat, moderate-to-humid humidity, and wet-summer rainfall can create ideal conditions for pests and diseases. Consistent monitoring and proactive measures are key to keeping your cabbage healthy.

Companion planting can give your cabbage a boost in the Midwest garden. Green beans help fix nitrogen in the soil, benefiting cabbage growth. Celery can deter cabbage white butterflies, while onions repel many pests. Potatoes are good neighbors as well. Dill attracts beneficial insects that prey on cabbage pests.

Avoid planting cabbage near tomatoes, strawberries, or peppers. Tomatoes and strawberries compete for the same nutrients, while peppers can attract pests that also affect cabbage.