Cabbage in Zone 5B — Great Plains

Cabbage thrives in our Plains gardens, delivering a satisfying crunch and mild flavor that's perfect for everything from coleslaw to hearty stews. The crisp texture holds up well, even after summer's intense sunshine, and the taste is a welcome addition to any meal.

Our extreme temperature swings and variable rainfall can be a challenge, but starting cabbage indoors gives you a head start, ensuring a great harvest within our roughly 178-day growing season. Careful planning and timely planting make cabbage a reliable crop for Plains gardeners.

Starting cabbage indoors is key in our region to get a jump on the growing season. Begin in mid February through early March, roughly six weeks before you plan to transplant. Use seed trays with a good seed-starting mix and keep them in a warm location, ideally around 70°F, until germination.

Consistent moisture is important. Bottom watering is an easy way to keep the soil evenly moist without disturbing the seedlings. Place the tray in a shallow container of water until the soil surface is damp.

Remember our spring weather can be unpredictable. Provide supplemental light with a grow light, especially during cloudy stretches, to ensure strong, healthy seedlings.

Transplant your cabbage seedlings outdoors in early April through early May, after hardening them off for about a week. Gradually expose them to outdoor conditions, starting with a few hours of shade and increasing the time and sunlight each day. This helps them adjust to the wind and temperature swings common in our region.

Plant seedlings 12-18 inches apart in rows. Dig a hole slightly larger than the root ball and gently place the seedling in, backfilling with soil. Water thoroughly after transplanting.

Keep an eye on the forecast. A late frost can still happen, so be prepared to cover your young plants if needed.

Cabbage needs consistent moisture to thrive, but our variable rainfall in the Plains can make this tricky. Aim for about 1 inch of water per week, either from rainfall or irrigation. The "finger test" is a good way to check: stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water.

In the cooler spring months, watering once or twice a week might be enough. As the summer heat cranks up, especially with temperatures around 93°F, you may need to water more frequently. Water at the base of the plants to avoid wetting the leaves, which can increase the risk of fungal diseases in our low-to-moderate humidity.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can lead to root rot, indicated by yellowing leaves and a generally unhealthy appearance. Mulching around your cabbage plants with straw or wood chips helps retain moisture in our often-dry climate and keeps the soil cooler during the summer heat.

You can expect your first cabbage harvest from mid June through early August, about 70 days after transplanting. The best sign that a cabbage head is ready is its firmness. Give it a gentle squeeze; it should feel solid and dense.

Also, check that it's reached the full size for its variety. To harvest, use a sharp knife to cut the head at its base, leaving a few outer leaves attached.

As our first frost approaches around mid- October, harvest any remaining heads, even if they aren't quite fully mature. Smaller heads can still be used in cooking.

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

Cabbage Worms

• What it looks like: Smooth green caterpillars munching on leaves, leaving irregular holes. You'll also see dark green droppings and white butterflies flitting around.
• What causes it: These are the larvae of the white cabbage butterflies. They can have multiple generations in a single season, especially when the weather warms up.
• How to fix/prevent it: Bt spray is very effective and safe. Floating row covers are great for preventing butterflies from laying eggs. Handpicking the caterpillars is also an option. Planting aromatic herbs like thyme and sage nearby can deter them, and you can also encourage parasitic wasps.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but loopers move in a distinctive "looping" motion. They also chew holes in leaves.
• What causes it: Cabbage loopers are another type of caterpillar that feeds on brassicas.
• How to fix/prevent it: Use Bt spray, handpick them, and encourage beneficial insects like parasitic wasps. Row covers also work well.

Splitting

• What it looks like: The cabbage head cracks open.
• What causes it: Inconsistent watering. A sudden heavy rain after a dry spell causes the head to swell rapidly, resulting in splitting.
• How to fix/prevent it: Consistent watering is key. Mulching helps retain moisture. If a heavy rain is predicted after a dry period, consider making a shallow cut on one side of the head to relieve pressure.

Clubroot

• What it looks like: Stunted growth, wilting in the afternoon heat, and yellowing leaves. When you dig up the plant, the roots are swollen, distorted, and club-shaped.
• What causes it: A soil-borne pathogen (Plasmodiophora brassicae) that can stick around for 10+ years. It likes 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 sterile mix to prevent infection.

Great Plains Specific Challenges: Our hot summer heat can stress cabbage, making it more susceptible to pests and diseases. Variable rainfall means you need to be extra vigilant about watering. Wind protection is essential to prevent damage to the large leaves. Hail risk is ever present, so consider protective netting if hail is in the forecast.

Companion planting can really boost your cabbage crop in the Plains. Green beans are a great companion because they fix nitrogen in the soil, which cabbage loves. Celery helps deter cabbage white butterflies. Onions and dill are also good choices, as their strong scents repel many common cabbage pests. Potatoes can also be good companions as they don't compete for the same nutrients.

Avoid planting cabbage near tomatoes, strawberries, or peppers. Tomatoes and peppers can stunt the growth of cabbage, and strawberries compete for the same nutrients.