Cabbage in Zone 4B — Great Plains

Cabbage is a rewarding crop for Plains gardeners. Its crisp texture and mild flavor make it perfect for slaws, soups, and roasting. Plus, there's nothing quite like the satisfaction of harvesting a hefty head of cabbage that *you* grew, right here on the prairie.

While our region can throw some extreme weather your way, cabbages are surprisingly resilient if you time things right. Our 149-day growing season is just long enough to get a good harvest, especially if you give your plants a head start indoors.

Start your cabbage seeds indoors from early to late March, about six weeks before you plan to transplant. This gives them a jump start against our unpredictable spring weather. Use seed trays or small pots filled with a good seed-starting mix.

Keep the trays warm (around 70°F) and provide plenty of light, either from a sunny window or a grow light. Water gently from the bottom to avoid damping off. Our springs here can be all over the place, so starting indoors is key to getting a reliable harvest.

Transplant your cabbage seedlings outdoors from late April through mid May, after the worst of the spring frosts have passed. Before planting, harden off the seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

Space the plants 12-18 inches apart in rows. Our spring weather can be tough on young plants, so make sure to protect them from strong winds if possible. A temporary windbreak can make a big difference.

Cabbage needs consistent moisture to thrive, but overwatering can be just as damaging as underwatering, especially with our variable rainfall. Aim to keep the soil consistently moist but not soggy. The finger test is your friend: stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water.

During hot, dry stretches, especially in July and August, you might need to water deeply a couple of times a week, providing about 1-1.5 inches of water each time. Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our low-to-moderate humidity. Look for signs of underwatering (wilting leaves) or overwatering (yellowing leaves).

A layer of mulch around the plants helps retain moisture and suppress weeds. Straw, grass clippings, or wood chips work well in our Plains climate.

You can expect to harvest your cabbage from late June through mid August, about 70 days after transplanting. The key is to check the heads regularly. A ripe cabbage head will feel firm and solid when squeezed. It should also be close to the full size for its variety.

To harvest, use a sharp knife to cut the head off at the base of the plant. If a hard frost is predicted in early October and you still have some heads that aren't quite ready, you can try covering them with blankets or tarps to extend the season a bit.

Here are some common problems you might encounter with cabbage in the Great Plains:

Cabbage Worms

• What it looks like: Smooth green caterpillars on brassica leaves. Irregular holes chewed in leaves. Dark green droppings. White butterflies hovering around plants.
• What causes it: Larvae of white cabbage butterflies. Multiple generations per season in warm climates.
• How to fix/prevent it: Bt spray is very effective. Floating row covers prevent egg laying. Handpick caterpillars. Interplant with aromatic herbs (thyme, sage). Encourage parasitic wasps.

Cabbage Loopers

• What it looks like: Pale green caterpillars that move in a looping motion. They chew large, irregular holes in leaves, often leaving behind only the veins.
• What causes it: Cabbage looper moths lay their eggs on cabbage leaves, and the larvae hatch and feed on the plants.
• How to fix/prevent it: Similar to cabbage worms, Bt spray is effective. Handpicking can work for smaller infestations. Row covers can prevent the moths from laying eggs.

Splitting

• What it looks like: The cabbage head cracks open.
• What causes it: Inconsistent watering, especially heavy watering after a dry spell, causes the head to grow too quickly and burst. This is common after our unpredictable rainfall patterns.
• How to fix/prevent it: Water consistently and evenly. Mulch to retain moisture. Harvest heads as soon as they are mature to prevent them from splitting.

Clubroot

• What it looks like: Stunted growth, wilting in afternoon heat, yellowing leaves. Roots are swollen, distorted, and club-shaped when dug up.
• What causes it: Soil-borne pathogen (Plasmodiophora brassicae) that persists in soil for 10+ years. Favors acidic, wet soil.
• How to fix/prevent it: Raise soil pH to 7.0-7.2 with lime. Improve drainage. Rotate brassicas on a 7-year cycle. Remove and destroy infected plants (don't compost). Start transplants in sterile mix.

Great Plains Specific Challenges: Our hot summers, low-to-moderate humidity, and variable rainfall can stress cabbage plants. Consistent watering is crucial to prevent splitting. Wind protection is also important, as strong winds can damage leaves and dry out the soil. Keep a close eye on your plants and adjust your care as needed to help them thrive in our unique climate.

Good companions for cabbage include green beans, celery, onions, and potatoes. Green beans fix nitrogen in the soil, which benefits cabbage. Celery repels cabbage white butterflies. Onions deter many pests, and potatoes don't compete for the same nutrients. Dill attracts beneficial insects that prey on cabbage pests.

Avoid planting cabbage near tomatoes, strawberries, and peppers. Tomatoes can stunt the growth of cabbage. Strawberries and peppers are susceptible to similar pests and diseases, potentially increasing problems in your garden.