Cabbage in Zone 10B — Desert Southwest

Cabbage thrives in our mild Desert Southwest winters, offering a satisfyingly crisp and nutritious addition to your spring meals. Its versatility in slaws, stir-fries, and even grilled wedges makes it a rewarding crop to grow in your own garden.

Don't let our reputation for extreme heat scare you off. By timing your cabbage crop to mature before the worst of the summer heat hits, you can enjoy a successful harvest. Our 349-day growing season allows for a fantastic winter and spring crop of cabbage.

Starting cabbage indoors is the way to go for a spring harvest here. Begin in mid November through early December, 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 consider bottom-watering to prevent damping-off. Place the trays under grow lights or in a very bright window. Remember, we're starting these indoors because our spring warmth comes early.

Transplant your cabbage seedlings outdoors in early to late January. Before transplanting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sunlight and temperature fluctuations.

Space the seedlings 12-18 inches apart in well-draining soil. Even in January, keep an eye on the forecast, and be ready to cover your young plants if a hard freeze threatens.

Cabbage needs consistent moisture to thrive, but overwatering can be just as harmful as underwatering, especially in our alkaline soil. Aim to keep the soil consistently moist, but not soggy. Strive for "moderate" watering.

During the cooler months, check the soil moisture with the "finger test" – stick your finger about two inches deep into the soil. If it feels dry, it's time to water. Water deeply at the base of the plant, providing about 1-1.5 inches of water per week, depending on rainfall. Avoid overhead watering to prevent fungal diseases in our arid climate.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of organic mulch, like composted leaves or shredded bark, helps retain moisture and regulate soil temperature.

You can expect your first cabbage harvest from mid March through late April. Cabbage is ready to harvest when the head feels firm and solid when you give it a gentle squeeze. It should also be close to the full size for the variety you're growing.

To harvest, use a sharp knife to cut the head at the base of the plant. Leave the outer leaves intact, as they can sometimes produce smaller side shoots for a later harvest. As late December approaches and the first frost threatens, harvest any remaining mature heads to prevent damage.

Here are some common cabbage problems you might encounter in the Desert Southwest:

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, similar to inchworms. They chew large, irregular holes in leaves.
• What causes it: Cabbage looper moths lay eggs on cabbage plants. The larvae hatch and feed on the leaves.
• How to fix/prevent it: Handpick the loopers off the plants. Use Bt (Bacillus thuringiensis) spray, which is effective against young loopers. Encourage natural predators like parasitic wasps and lacewings.

Splitting

• What it looks like: The cabbage head cracks or splits open. This is most common after a period of drought followed by heavy watering.
• What causes it: Inconsistent watering, especially after periods of drought stress, causes the head to grow too quickly and split.
• How to fix/prevent it: Provide consistent, even watering. Avoid letting the soil dry out completely, then drenching it. Harvest cabbage heads as soon as they are mature to prevent 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.

Desert Southwest Specific Challenges: The extreme heat and intense sun can stress cabbage plants, making them more susceptible to pests and diseases. The arid climate requires careful attention to watering to prevent both drought stress and splitting. Our alkaline soil can also contribute to nutrient deficiencies, so amend your soil with compost before planting.

Companion planting can be a great help in our Desert Southwest gardens. Green beans fix nitrogen in the soil, benefiting cabbage. Celery deters cabbage white butterflies, reducing cabbage worm infestations. Onions and dill are said to repel various pests, helping to keep your cabbage plants healthy. Potatoes can improve the soil structure and drainage, which is especially helpful in our sometimes compacted soils.

Avoid planting cabbage near tomatoes, strawberries, and peppers. Tomatoes and peppers compete for the same nutrients and can attract similar pests. Strawberries can inhibit the growth of cabbage, so it's best to keep them separated.