Bok Choy in Zone 9A — Desert Southwest

Bok choy is a fantastic addition to your Desert Southwest garden. Its mild, slightly sweet flavor and crisp texture make it incredibly versatile in stir-fries, soups, and salads. Plus, harvesting your own fresh bok choy is incredibly satisfying, especially knowing you nurtured it through our unique climate.

Desert gardening definitely has its challenges, especially the extreme heat. But with careful timing, you can easily enjoy a bountiful bok choy harvest during our two growing seasons. Our long growing season of around 298 days gives you ample opportunity for success!

Starting bok choy indoors isn't essential in our climate, but it can give you a head start. If you want to get a jump on the spring season, sow seeds indoors from mid-January through early February, about four weeks before you plan to transplant. This allows the seedlings to get a bit larger before facing the elements.

Use seed trays or small pots filled with well-draining potting mix. Keep the soil consistently moist by bottom watering – set the tray in a shallow dish of water and let the soil absorb it from the bottom. This helps prevent damping off. Provide warmth and bright light, and you'll have seedlings ready to go as soon as the weather warms up a bit. Remember our spring can be very-early, so keep an eye on the forecast.

Transplant your bok choy seedlings outdoors from mid-February through late March. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Start with an hour or two of shade, increasing the time each day.

Plant seedlings 6-10 inches apart in well-draining soil. Keep in mind that even in late February, we can still get some unexpected temperature swings, so be prepared to protect your transplants with row covers if needed.

Direct sowing bok choy is a great option in our climate, especially for fall crops. Sow seeds directly into the garden from early February through mid-October. The key is timing it right to avoid the worst of the summer heat.

Prepare the soil by loosening it and adding compost. Plant seeds about ¼ inch deep and keep the soil consistently moist. Soil temps should be between 50-75°F for optimal germination. Thin seedlings to 6-10 inches apart once they emerge. Direct sowing eliminates the need for transplanting, but you’ll need to be vigilant about watering and protecting the young plants from pests.

Watering is critical for bok choy summer survival in the Desert Southwest. This plant needs consistent moisture to thrive, and our arid climate can quickly dry it out. Aim to keep the soil consistently moist, but not waterlogged.

During the cooler spring and fall months, water deeply about 1-2 times per week, providing about 1 inch of water each time. Use the finger test: stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water. During the monsoon season, you may need to adjust your watering schedule depending on rainfall. In the extreme heat of summer, you may need to water daily, especially if plants are in full sun.

Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases. Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to root rot, so make sure your soil drains well. A layer of mulch can help retain moisture and keep the soil cooler.

You can expect your first bok choy harvest from mid-March through mid-December, about 45 days after planting. You can harvest baby bok choy when it's 6-8 inches tall or wait for the full-size heads to reach 12-15 inches.

To harvest, cut the bok choy above the base, leaving the roots intact. This allows the plant to regrow and produce another harvest. You can continue harvesting leaves as needed until the plant starts to bolt.

As the first frost approaches in early December, harvest any remaining bok choy. Even though it's semi-hardy, a hard freeze can damage the leaves. With a bit of planning, you can have a continuous supply of fresh bok choy for most of the year.

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

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves, especially on young seedlings. You might see small dark beetles jumping when disturbed.
• What causes it: These small jumping beetles love to feed on brassicas. They're especially problematic for small, young plants.
• How to fix/prevent it: Use row covers to protect seedlings. Delay planting until plants are larger. Kaolin clay coating can deter them. Neem oil spray can also help. Interplant with basil or catnip. Healthy, vigorous plants can often outgrow the damage.

Cabbage Worms

• What it looks like: Smooth green caterpillars munching on leaves, leaving irregular holes. You'll also see dark green droppings and white butterflies fluttering around your plants.
• What causes it: These are the larvae of those white cabbage butterflies. They can go through multiple generations in our long, warm growing season.
• How to fix/prevent it: Bt spray is very effective. Floating row covers will prevent the butterflies from laying eggs. Handpick caterpillars whenever you see them. Interplant with aromatic herbs like thyme and sage to deter the butterflies.

Slugs

• What it looks like: Irregular holes in leaves, especially those close to the ground. Look for silvery slime trails on leaves and soil. Damage is often worse at night.
• What causes it: These gastropods feed at night in moist conditions. They hide under mulch, boards, and debris during the day.
• How to fix/prevent it: Use beer traps (shallow dishes of beer sunk into the soil). Iron phosphate bait is pet-safe. Remove any hiding spots. Water in the morning so the soil surface dries out by evening. Copper tape around beds can deter them. Diatomaceous earth around plants also works.

Bolting in Heat

• What it looks like: The plant sends up a flower stalk, and the leaves become tough and bitter. Overall harvest quality declines.
• What causes it: Bok choy is a cool-season crop, and it bolts when temperatures rise too high. Brassicas tend to bolt when days consistently exceed 80°F.
• How to fix/prevent it: Time your plantings for the cooler parts of the year (spring and fall). Choose bolt-resistant varieties. Provide shade during warm spells. Mulch to keep the soil cool. Harvest before bolting progresses too far.

Desert Southwest Specific Challenges: Our extreme heat, arid humidity, and occasional monsoon rains can all impact bok choy. The heat can cause bolting, while the low humidity means you need to be extra vigilant about watering.

Good companions for bok choy in the Desert Southwest include garlic and onions, which deter pests. Beets help improve soil structure and nutrient availability. Lettuce and spinach, being low-growing, provide ground cover and help retain moisture in our arid climate.

Avoid planting bok choy near strawberries or tomatoes. Strawberries compete for nutrients, and tomatoes can attract pests that also affect bok choy. Companion planting can really make a difference in our challenging growing conditions.