Cabbage in Zone 5A — Great Plains

Cabbage is a rewarding crop for Plains gardeners. Its crisp texture and mild flavor make it a versatile addition to slaws, stir-fries, and more. Plus, there's something deeply satisfying about harvesting a dense, perfect head of cabbage you grew yourself, even with our sometimes unpredictable weather.

Our Great Plains climate can throw curveballs, with its extreme temperature swings and occasional hail. But by starting cabbage indoors and timing your planting carefully, you can easily work within our 168-day growing season and enjoy a successful harvest.

Starting cabbage indoors gives you a head start against our short growing season. Begin in late February through mid March, about six weeks before you plan to transplant. Use seed trays or small pots filled with a good seed-starting mix.

Keep the soil consistently moist, and provide plenty of light – a grow light works wonders. Consider bottom watering: set the tray in a shallow pan of water and let the soil absorb moisture from the bottom. This prevents damping off. Spring in the Plains can be variable, so indoor starts are essential.

Transplant your cabbage seedlings outdoors in mid April through early May, after 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 acclimates them to the sun and wind.

Space plants 12-18 inches apart in rows. Keep an eye on the weather forecast; a late cold snap can still happen! Be ready to cover your seedlings if necessary.

Cabbage needs consistent moisture to thrive, but overwatering is just as bad as underwatering, especially with our variable rainfall. Aim for about 1 inch of water per week, either from rain or irrigation. The "finger test" is your friend: 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, though our low-to-moderate humidity helps mitigate this risk. Water deeply and less frequently, rather than shallowly every day.

During hot summer stretches, you might need to water more often. Wilting leaves in the afternoon are a sign of underwatering. Cracked or split heads can indicate inconsistent watering – usually heavy watering after a dry spell.

A layer of mulch around your cabbage plants helps retain moisture and suppress weeds. Straw or grass clippings work well in our region.

You can expect to harvest your cabbage from mid June through early August, about 70 days after transplanting. The key sign of ripeness is a firm, solid head. Give the head a gentle squeeze – it should feel dense and compact.

Cut the head at the base with a sharp knife. Leave the outer leaves intact; they can sometimes produce smaller side heads later in the season.

As the first frost approaches in early October, harvest any remaining heads, even if they aren't quite full size. Smaller cabbages are still delicious in soups and stews.

Cabbage Worms

• What it looks like: Smooth green caterpillars chewing irregular holes in leaves. You'll also see dark green droppings and white cabbage butterflies fluttering around.
• What causes it: Larvae of those pretty white cabbage butterflies. They can go through multiple generations during our warm summers.
• How to fix/prevent it: Bt spray is your best friend. Floating row covers keep butterflies from laying eggs. Handpick any caterpillars you see. Plant aromatic herbs like thyme and sage nearby to deter them.

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: Another type of moth larva that thrives in warm weather.
• How to fix/prevent it: Bt spray works on these too. Handpicking is effective for small infestations. Encourage beneficial insects like parasitic wasps.

Splitting

• What it looks like: The cabbage head cracks or splits open.
• What causes it: Inconsistent watering. Our variable rainfall – going from drought to deluge – is a major culprit. Rapid growth after a dry spell is the main cause.
• How to fix/prevent it: Consistent watering is key. Mulch helps retain moisture. Choose varieties that are less prone to splitting.

Clubroot

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

Great Plains Specific Challenges: Our hot summers can stress cabbage, making them more susceptible to pests and diseases. The low-to-moderate humidity helps a bit with fungal problems, but consistent watering is crucial to prevent splitting, especially with our unpredictable rainfall. Wind protection is always a good idea to prevent damage to the large leaves.

Green beans are great companions for cabbage. They fix nitrogen in the soil, which helps cabbage grow. Celery also works well, supposedly deterring cabbage white butterflies. Onions and potatoes can help repel some cabbage pests. Dill is another good choice; it attracts beneficial insects that prey on cabbage worms.

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