Cabbage in Zone 3A — Great Plains

Cabbage is a rewarding crop to grow in the Great Plains. Its crisp texture and slightly sweet flavor make it a versatile addition to many meals, from slaws to soups. Plus, there's a certain satisfaction in harvesting a beautiful, tightly-packed head of cabbage that *you* grew, especially after battling our variable Plains weather.

Sure, we have our share of challenges with extreme temperature swings and the occasional hail risk. But with careful timing, you can absolutely grow delicious cabbage here. Our intense sunshine helps them thrive, and with a 108-day growing season, you have just enough time to get a good harvest.

Starting your cabbage indoors is the way to go in our neck of the woods. Begin your seeds indoors from late March through mid April, about six weeks before you plan to transplant. This gives them a head start before our unpredictable spring weather hits.

Use seed trays filled with a good seed-starting mix. Keep them warm – around 70°F – until the seedlings emerge. A heat mat can really help with that. Once they're up, make sure they get plenty of light, either from a grow light or a very sunny window. Don't forget to water from the bottom to avoid damping off.

Our springs are known for being variable, so starting indoors gives your cabbage seedlings the best chance of survival when they eventually face the elements.

Transplant your cabbage seedlings outdoors from mid May through early June, after the risk of hard frost has passed. Before you plant them in the garden, be sure to harden them off. This means gradually exposing them to outdoor conditions for about a week.

When transplanting, space them 12-18 inches apart to give them plenty of room to grow. Our late spring weather can still be a bit unpredictable, so keep an eye on the forecast and be prepared to cover them if a late frost threatens. Wind protection is essential, especially for young plants.

Cabbage needs consistent moisture to thrive, but overwatering is just as bad as underwatering, especially in our climate. The key is to find a balance. During our hot Plains summers, you'll likely need to water your cabbage deeply a couple of times a week.

Stick your finger about two inches into the soil near the base of the plant. If it feels dry, it's time to water. Aim for about 1-1.5 inches of water per week, either from rainfall or irrigation. With our low-to-moderate humidity, watering at the base of the plant is usually best to avoid fungal diseases.

Watch for signs of underwatering, like wilting leaves. Overwatering can cause yellowing leaves and potentially lead to root rot. Mulching around your cabbage plants with straw or wood chips can help retain moisture in the soil and suppress weeds, which is a big help during our variable rainfall periods. Remember, heavy watering after a dry spell can cause the heads to split, so try to maintain consistent moisture levels.

You can expect your first cabbage harvest from mid July through early September, about 70 days after transplanting. The best way to tell if a cabbage is ready to harvest is to gently squeeze the head. If it feels firm and solid, it's ready to go. It should also be the full size for the variety you're growing.

To harvest, simply cut the head off at the base with a sharp knife. Leave a few of the outer leaves intact to protect the remaining stem. Cabbage doesn't ripen off the vine, and it's not a continuous harvest crop, so you'll harvest the whole head at once.

As our first frost approaches in early September, harvest any remaining mature heads. Even if they aren't quite as large as you'd hoped, they'll still be delicious. Any heads that are too small can be used in stir-fries or soups.

Here are some common problems you might encounter growing 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 can occur during our warm summers.
• How to fix/prevent it: Bt spray is very effective. Floating row covers prevent egg laying. Handpick caterpillars. Interplant with aromatic herbs like thyme and sage. Encourage parasitic wasps.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but these caterpillars move with a distinctive looping motion. They also chew holes in leaves.
• What causes it: Another type of moth larvae that thrives in warm weather.
• How to fix/prevent it: Similar to cabbage worms, use Bt spray, handpick, and use row covers.

Splitting

• What it looks like: The cabbage head cracks open.
• What causes it: Inconsistent watering. A sudden heavy watering after a dry spell causes the head to grow too quickly, leading to splitting. Our variable rainfall patterns can make this a challenge.
• How to fix/prevent it: Maintain consistent soil moisture. Water deeply and regularly, especially during dry periods. Mulch to help retain moisture. Harvest heads as soon as they are mature to reduce the risk of 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. Heavy clay soils common in the Plains can exacerbate drainage issues.
• 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 region's hot summers, low-to-moderate humidity, and variable rainfall can create challenges for cabbage. The heat can stress plants, making them more susceptible to pests and diseases. The variable rainfall can lead to inconsistent soil moisture, increasing the risk of splitting. Wind protection is also important, as strong winds can damage the large leaves.

Companion planting can really help your cabbage thrive. Green beans are a great choice because they fix nitrogen in the soil, which cabbage loves. Celery is said to deter cabbage white butterflies, reducing the risk of cabbage worms. Onions also deter pests, and potatoes can help break up the soil, improving drainage. Dill attracts beneficial insects that prey on cabbage pests.

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