Cabbage in Zone 8B — Desert Southwest

Cabbage is a rewarding crop to grow in our Desert Southwest gardens. Nothing beats the fresh, crisp taste of homegrown cabbage in slaws, stir-fries, or even a simple side dish. Plus, successfully growing a leafy head of cabbage in our challenging climate is incredibly satisfying.

Our extreme heat and alkaline soil can seem daunting, but with careful timing and attention, you can absolutely grow cabbage here. Our long, 279-day growing season allows us to utilize both a spring and fall planting window, giving us ample opportunity for a successful harvest.

Starting your cabbage indoors is the way to go in our region for a spring harvest. Begin sowing seeds indoors from late December through mid January, about six weeks before you plan to transplant them outside. This head start is crucial given our very-early spring.

Use seed trays or small pots filled with a good quality seed-starting mix. Keep the soil consistently moist, and consider bottom watering to avoid disturbing the delicate seedlings. Place the trays in a warm location with plenty of light, either from a sunny window or a grow light.

Transplant your cabbage seedlings outdoors from mid February through mid March. Before transplanting, harden them off 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 a sunny spot with well-draining soil. Be mindful of potential temperature swings at this time of year that can stress young plants. Protect them with row covers if a late freeze is predicted.

Cabbage needs consistent moisture to thrive, but overwatering can be just as detrimental, especially in our heavy, alkaline soils. The key is to find the right balance for our arid Desert Southwest climate. Aim for about 1-1.5 inches of water per week.

Use the finger test to check the soil moisture about two inches deep. If it feels dry, it's time to water. During the hotter parts of spring, you may need to water more frequently. Water deeply at the base of the plant to avoid wetting the foliage, which can lead to fungal issues in our monsoon season.

Signs of underwatering include wilting leaves and stunted growth. Overwatering can cause yellowing leaves and root rot. A layer of organic mulch around the base of the plants helps retain moisture and regulate soil temperature.

You can expect your first cabbage harvest from late April through early June, about 70 days after transplanting. The best way to tell if a cabbage head is ready to harvest is to gently squeeze it. It should feel firm and solid.

Cut the head off at the base with a sharp knife, leaving a small stem attached. If you're approaching our first frost in early December and still have some smaller heads, you can try covering them with a frost blanket to extend the harvest a bit longer.

Here are some common problems you might encounter growing cabbage 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. They chew large holes in leaves, leaving ragged edges.
• What causes it: Similar to cabbage worms, these are the larvae of moths. They thrive in warm weather.
• How to fix/prevent it: Bt spray works well. Inspect plants regularly and handpick loopers. Encourage beneficial insects like lacewings and ladybugs.

Splitting

• What it looks like: The cabbage head cracks open.
• What causes it: Inconsistent watering, especially heavy watering after a dry spell. Rapid growth spurts due to temperature fluctuations can also contribute. This is especially relevant with our monsoon moisture.
• How to fix/prevent it: Maintain consistent soil moisture. Water deeply but less frequently. Mulch around the plants. Harvest 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: Our extreme heat can stress cabbage plants, making them more susceptible to pests and diseases. The arid humidity can also lead to issues like sunscald. Monitor your plants closely and provide shade if necessary during the hottest part of the day. The monsoon season can bring welcome moisture, but also the risk of overwatering and fungal problems.

Companion planting can be a great way to improve the health and productivity of your cabbage. Green beans are good companions because they fix nitrogen in the soil, which cabbage needs. Celery helps to repel cabbage white butterflies, reducing the risk of cabbage worms.

Onions and dill are also beneficial companions, as their strong scents deter pests. Avoid planting cabbage near tomatoes, strawberries, or peppers. Tomatoes and peppers compete for nutrients, while strawberries can attract slugs and snails that may also damage cabbage.