Bok Choy in Zone 7A — Desert Southwest

Bok choy is a fantastic addition to your Desert Southwest garden. Its mild, slightly sweet flavor is delicious in stir-fries, soups, or even grilled. Plus, you'll get a real sense of satisfaction harvesting fresh greens from your own backyard during our mild spring and fall seasons.

Gardening in our region presents unique challenges like extreme heat and alkaline soil. But with careful timing and a few tricks, you can successfully grow bok choy during our two growing seasons. Our 230-day growing season means you can plant in spring and again in the fall.

Starting bok choy indoors isn't essential, but it can give you a head start, especially for a spring crop. If you want to go this route, begin your seeds indoors from mid-February through mid-March, about four weeks before you plan to transplant. Use seed trays with a good seed-starting mix, and keep them in a warm spot with plenty of light.

Bottom watering is key to prevent damping off. Place your tray in a shallow dish of water, allowing the soil to soak it up from the bottom. Given our very-early spring character in the Desert Southwest, indoor starting helps you jump ahead of any late cold snaps.

Transplant your bok choy seedlings outdoors from late March through early May. 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, preventing transplant shock.

Space your plants 6-10 inches apart in well-draining soil. Keep an eye on the weather forecast—even in late March and April, we can sometimes get unexpected temperature swings here. Protect young transplants with row covers if frost threatens.

Direct sowing bok choy is a great option, especially for your fall crop. Sow seeds from mid-March through mid-September, aiming for when soil temperatures are consistently between 50°F and 75°F. Prepare your soil by loosening it and amending with compost to improve drainage and fertility.

Plant seeds about ¼ inch deep, spacing them 6-10 inches apart. Direct sowing eliminates transplant shock, but you'll need to be diligent about watering, especially during our hot, dry spring and early summer. Thin seedlings as they grow to ensure proper spacing.

Bok choy needs consistent moisture, especially in our arid Desert Southwest climate. Aim to keep the soil evenly moist, but not waterlogged. This is key to preventing bolting and ensuring healthy growth.

In the spring and fall, water deeply about 1-2 times per week, providing about 1 inch of water each time. During the monsoon season, let the rainfall supplement your watering schedule, but check the soil moisture regularly. In the hottest part of the summer, you may need to water daily, especially if plants are in full sun. Use the "finger test" – stick your finger about 2 inches 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 in our climate. Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. Apply a layer of organic mulch around your bok choy plants to help retain moisture and keep the soil cool.

You can expect your first harvest of bok choy from late April through mid-November, depending on when you planted. Bok choy is ready to harvest about 45 days after planting. Harvest baby bok choy when the heads are 6-8 inches tall for a more tender flavor.

For full-sized bok choy, wait until the heads reach 12-15 inches. To harvest, cut the head above the base, leaving the roots intact. This allows the plant to regrow and produce additional leaves for a continuous harvest.

As the first frost approaches in early November, harvest any remaining bok choy, even if it's not fully mature. You can use these smaller leaves in salads or stir-fries. If a light frost is predicted, you can cover your plants with a frost blanket to extend the harvest a bit longer.

Here are some common problems you might encounter growing bok choy in the Desert Southwest, and how to deal with them:

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves, especially on young seedlings. You might see small, dark beetles that jump when disturbed.
• What causes it: Small jumping beetles that feed on leaves. They're most damaging to small, young plants, and the dry conditions in our region can stress plants, making them more susceptible.
• How to fix/prevent it: Use row covers to protect seedlings during their vulnerable stage. Delay planting until plants are larger. Kaolin clay coating can deter them. Neem oil spray can help. Interplant with basil or catnip. Healthy, vigorous plants outgrow the damage.

Cabbage Worms

• What it looks like: Smooth green caterpillars on brassica leaves. Irregular holes chewed in leaves. Dark green droppings. You might see white butterflies hovering around your plants.
• What causes it: Larvae of white cabbage butterflies. They can have multiple generations per season in our warm climate.
• 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.

Slugs

• What it looks like: Irregular holes in leaves, especially on low-growing plants. Silvery slime trails on leaves and soil. Damage is worse at night and in wet weather.
• What causes it: Gastropods that feed at night in moist conditions. They hide under mulch, boards, and debris during the day. The monsoon season can create ideal conditions for slugs.
• How to fix/prevent it: Beer traps (shallow dish of beer sunk into the soil). Iron phosphate bait (pet-safe). Remove hiding spots. Water in the morning so the soil surface dries by evening. Copper tape around beds. Diatomaceous earth around plants.

Bolting in Heat

• What it looks like: The cool-season crop sends up a flower stalk when temperatures rise. Leaves become tough and bitter, and harvest quality declines.
• What causes it: Extended warm temperatures above the crop's comfort zone. Bok choy bolts when days consistently exceed 80°F. Our extreme heat in the summer is a major trigger.
• How to fix/prevent it: Time plantings for cool weather (spring/fall). Choose bolt-resistant varieties. Provide shade during warm spells – shade cloth is essential. Mulch to keep the soil cool. Harvest before bolting progresses.

Desert Southwest Specific Challenges: Our extreme heat, arid humidity, and intense sun can all stress bok choy. Using shade cloth, choosing bolt-resistant varieties, and providing consistent moisture are crucial for success. The monsoon season can bring needed rainfall, but also increases the risk of fungal diseases and slug damage, so monitor your plants closely.

Good companions for bok choy include garlic and onions. These alliums help deter pests with their strong scent. Beets are also a good choice, as they don't compete for the same nutrients and can help loosen the soil. Lettuce and spinach are also good companions, as they have similar growing requirements and can provide ground cover to help retain moisture.

Avoid planting bok choy near strawberries or tomatoes. Strawberries compete for nutrients, and tomatoes can attract pests that also affect bok choy. By choosing the right companions, you can create a thriving and productive garden, even in our challenging Desert Southwest climate.