Cabbage in Zone 8A — Desert Southwest

Cabbage thrives in our two growing seasons, offering crisp texture and mild flavor perfect for slaws, stir-fries, and even grilling. Nothing beats the satisfaction of harvesting a beautiful, tightly-packed head of cabbage that you nurtured yourself, especially knowing it's a crop that can handle the cooler temperatures we see.

While the extreme heat of our Desert Southwest summers might seem daunting, the key to successful cabbage growing here is timing. By starting early indoors and focusing on spring harvests, you can enjoy a bountiful cabbage crop during our mild weather, taking full advantage of our long 265-day growing season.

Start your cabbage seeds indoors in early to late January, giving them about six weeks to get a head start before transplanting. 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 in a warm location (around 70°F) and provide plenty of light – a grow light works wonders. Remember, our spring season here in the Desert Southwest arrives very early, so getting those seeds going indoors is crucial.

Transplant your cabbage seedlings outdoors from mid-February through mid-March. Before planting, 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 plants 12-18 inches apart in well-draining soil. Keep an eye on the forecast; late cold snaps can still happen, so be prepared to cover your young plants if necessary.

Cabbage needs consistent moisture to thrive, but overwatering can be just as detrimental, especially in our alkaline soil. Aim to keep the soil evenly moist, but not soggy. The finger test is your best friend here: stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water.

During our mild spring, you'll likely need to water deeply about 1-2 times per week, providing about 1-1.5 inches of water each time. Water at the base of the plants to avoid wetting the leaves, which can lead to fungal problems in our arid climate, even though humidity is low. As the monsoon season approaches (typically starting in July, but you'll be done with this crop by then), be extra vigilant about drainage.

Signs of underwatering include wilting leaves and slow growth. Overwatering can cause yellowing leaves and root rot. A layer of organic mulch around your cabbage plants helps retain moisture in the soil and regulate soil temperature, which is especially helpful in our region.

You can expect your first cabbage harvest from late April through mid-June, about 70 days after transplanting. The key is to look for signs of maturity rather than strictly relying on the calendar.

A ripe cabbage head will feel firm and solid when you gently squeeze it. It should also be close to the full size for its variety. To harvest, use a sharp knife to cut the head off at the base of the plant.

As our first frost approaches in late November, keep an eye on any late-planted cabbage. While they can tolerate frost, a hard freeze can damage the heads. Harvest any remaining heads before a significant freeze is predicted.

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

Cabbage Worms

• What it looks like: Smooth green caterpillars munching on leaves, leaving irregular holes and dark green droppings. You might also spot white butterflies fluttering around your plants.
• What causes it: These are the larvae of white cabbage butterflies. They thrive in our warm climate and can have multiple generations in a single season.
• How to fix/prevent it: Bt spray is very effective at controlling cabbage worms. Floating row covers can prevent the butterflies from laying eggs on your plants. You can also handpick the caterpillars and interplant with aromatic herbs like thyme or sage to deter the butterflies. Encourage parasitic wasps, which prey on cabbage worms.

Cabbage Loopers

• What it looks like: Similar to cabbage worms, but these caterpillars move in a looping motion. They also chew holes in leaves and can quickly defoliate your plants.
• What causes it: Cabbage loopers are another type of caterpillar that feeds on brassicas. They are more tolerant of warmer temperatures than cabbage worms, making them a common pest in our region.
• How to fix/prevent it: Bt spray is also effective against cabbage loopers. Handpicking can help with smaller infestations. Keep your garden free of weeds, as they can serve as a host for the loopers.

Splitting

• What it looks like: The cabbage head cracks or splits open.
• What causes it: Splitting is usually caused by inconsistent watering. A period of drought followed by heavy watering causes the head to swell too quickly, leading to cracks. This can be especially problematic with our monsoon season's sporadic downpours.
• How to fix/prevent it: Maintain consistent soil moisture by watering regularly, especially during dry spells. Mulching can help regulate soil moisture. Harvest cabbage heads as soon as they are mature to prevent them from splitting.

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: This is a soil-borne disease caused by the pathogen *Plasmodiophora brassicae*. It thrives in acidic, wet soil and can persist in the soil for many years.
• How to fix/prevent it: Raise the soil pH to 7.0-7.2 with lime. Improve soil drainage. Rotate brassicas on a 7-year cycle. Remove and destroy infected plants (do not compost them). Start transplants in a sterile mix to avoid introducing the pathogen.

Desert Southwest Specific Challenges: The extreme heat can stress cabbage plants, making them more susceptible to pests and diseases. Our alkaline soil can also be a challenge, so be sure to amend your soil with compost to improve drainage and nutrient availability. The monsoon season's heavy rains can lead to splitting, so monitor soil moisture carefully and harvest heads promptly.

Good companions for cabbage in the Desert Southwest include green beans, celery, onions, potatoes, and dill. Green beans fix nitrogen in the soil, benefiting cabbage growth. Celery and onions deter cabbage moths. Potatoes don't compete for the same nutrients. Dill attracts beneficial insects that prey on cabbage pests.

Avoid planting cabbage near tomatoes, strawberries, and peppers. Tomatoes and peppers compete for the same nutrients and can attract similar pests. Strawberries can stunt cabbage growth. These combinations create conditions where one or both plants are weaker in our Desert Southwest climate.