Bok Choy in Zone 3A — Mountain West

Bok Choy is a fantastic addition to any Mountain West garden. Its crisp, mild flavor shines in stir-fries, soups, and salads, and the cool nights even in summer here actually enhance its sweetness. You'll find it's incredibly satisfying to harvest your own fresh greens, especially in our short growing season.

Our high altitude, intense sun, and short season do present challenges. But with careful timing, you can absolutely enjoy a bountiful Bok Choy harvest. With a 96-day growing season, we need to get a jump start!

Starting Bok Choy indoors is an option, but not always necessary given its quick maturity. If you want a really early harvest, start seeds indoors from late April through mid May, about 4 weeks before you plan to transplant. This can give you a head start before our last frost, which often lingers into early June.

Use seed trays with a good seed-starting mix. Keep them warm (around 70°F) and provide plenty of light – a grow light is ideal. Bottom watering helps prevent damping off. Remember our spring weather can be unpredictable, so indoor starts offer a buffer.

Transplant your Bok Choy seedlings outdoors from early June through early July, once the danger of frost has passed. Be sure to harden them off for about a week beforehand by gradually exposing them to outdoor conditions. This helps them adjust to the intense sun and cooler nights.

Space the seedlings 6-10 inches apart. Keep an eye on the forecast – late frosts or even hail are always a possibility in early June. A row cover can offer extra protection.

Direct sowing Bok Choy is a great option in the Mountain West, especially for a later harvest. Sow seeds from mid May through early July. This takes advantage of the warming soil and longer days.

Prepare your soil by loosening it and adding compost to improve drainage and fertility. Bok Choy prefers a soil temperature of around 60-70°F for germination. Plant seeds about ¼ inch deep and space them 6-10 inches apart. Thin seedlings as needed.

Watering is critical for Bok Choy in our dry Mountain climate. Consistent moisture is key, as drought stress can cause it to bolt prematurely. Aim to keep the soil consistently moist, but not waterlogged.

During the warmer months (late June through August), 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. With our low humidity, watering at the base of the plants is preferable to overhead watering, which can lead to fungal issues in other climates but isn't a concern here.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around your Bok Choy plants helps retain moisture and regulate soil temperature.

You can expect your first Bok Choy harvest from early July through mid September, about 45 days after planting. You can harvest baby bok choy when the leaves are 6-8 inches tall for a more tender flavor. For larger heads, wait until they reach 12-15 inches.

To harvest, cut the plant above the base, leaving the roots intact. This allows the plant to regrow and provide you with multiple harvests. Continue harvesting regularly to encourage new growth.

As the first frost approaches in early September, harvest any remaining Bok Choy, even if it's not fully mature. You can use it in stir-fries or soups. Row covers can extend the harvest a bit longer into the fall.

Here are some common problems you might encounter with Bok Choy in the Mountain West:

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves. Small dark beetles that jump when disturbed.
• What causes it: These small jumping beetles feed on leaves, especially of young plants. They thrive in dry conditions, which we often have.
• How to fix/prevent it: Row covers are your best friend for protecting seedlings. You can also try coating the leaves with kaolin clay or spraying with neem oil. Interplanting with basil or catnip can also help deter them.

Cabbage Worms

• What it looks like: Smooth green caterpillars on the leaves, with irregular holes chewed in them. You might also see dark green droppings and white butterflies fluttering around.
• What causes it: These are the larvae of cabbage butterflies.
• How to fix/prevent it: Bt spray is very effective and safe. Floating row covers will prevent the butterflies from laying eggs. Handpicking the caterpillars also works, or interplant with aromatic herbs like thyme or sage to confuse the butterflies.

Slugs

• What it looks like: Irregular holes in leaves, especially on low-growing plants, and silvery slime trails.
• What causes it: Slugs feed at night in moist conditions.
• How to fix/prevent it: Beer traps (shallow dishes of beer sunk into the soil) work wonders. Iron phosphate bait is pet-safe. Remove any hiding spots like boards or debris. Water in the morning so the soil surface dries out by evening. Diatomaceous earth around plants can also help.

Bolting in Heat

• What it looks like: The plant sends up a flower stalk, and the leaves become tough and bitter.
• What causes it: Bok Choy is a cool-season crop and bolts when temperatures rise consistently above 80°F. Our intense sun can exacerbate this.
• How to fix/prevent it: Time your plantings for cooler weather in spring and fall. Choose bolt-resistant varieties. Provide shade during warm spells with shade cloth. Mulch to keep the soil cool. Harvest promptly before bolting progresses too far.

Mountain West Specific Challenges: Our moderate-at-altitude heat, low humidity, and dry rainfall can be a mixed bag for Bok Choy. The intense sun can stress the plants, making them more susceptible to bolting, but the low humidity helps prevent fungal diseases. Consistent watering is crucial to combat the dryness and prevent bolting.

Good companions for Bok Choy include garlic and onions, whose strong scents deter pests like flea beetles and cabbage moths. Beets improve the soil structure and provide nutrients. Lettuce and spinach, as fellow cool-season crops, enjoy similar growing conditions and won't compete for resources.

Avoid planting Bok Choy near strawberries, as they can attract slugs. Tomatoes can also inhibit Bok Choy's growth, potentially due to allelopathic compounds they release into the soil.