Bok Choy in Zone 4B — Great Plains

Bok choy, with its mild, slightly sweet flavor, is a great addition to stir-fries, soups, and salads, and it's surprisingly well-suited to our Great Plains gardens. Its quick growth means you can get multiple harvests even with our shorter growing season, and fresh, homegrown bok choy tastes so much better than anything you'll find at the grocery store.

Our extreme weather can be a challenge, but with careful timing, you can definitely succeed with bok choy. Our 149-day growing season offers a decent window for both spring and fall crops, allowing you to enjoy fresh greens even when the weather throws us curveballs.

Starting bok choy indoors is possible, but honestly, it's often not necessary here in the Plains. If you're eager for an extra-early start, aim to sow seeds indoors from late March through late April, about four weeks before you plan to transplant. Use seed trays with a good seed-starting mix, and provide consistent warmth and bright light – a simple shop light works wonders.

Bottom watering is key to prevent damping off; just set the tray in a shallow dish of water until the soil surface is moist. Our variable spring weather can bring unexpected cold snaps, so having seedlings ready to transplant as soon as the soil warms up can give you a jumpstart.

Transplant your bok choy seedlings outdoors from early May through mid June, once the risk of hard frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the intense Plains sunshine and wind.

Space the plants 6-10 inches apart in well-drained soil. Keep an eye on the forecast – a late-season hailstorm can decimate young plants, so be ready to cover them if needed.

Direct sowing is a perfectly viable option for bok choy in our region, and it can save you the hassle of starting seeds indoors. Sow seeds directly into the garden from late April through early August. The soil should be at least 50°F for good germination.

Prepare the soil by loosening it and adding compost for fertility. Sow seeds about ¼ inch deep and keep the soil consistently moist. Thin seedlings to 6-10 inches apart once they emerge. The advantage of direct sowing is that the plants avoid transplant shock, but they are more vulnerable to pests and extreme weather when they are small.

Bok choy needs consistent moisture to thrive, especially in our hot Plains summers. Aim to keep the soil consistently moist, but not waterlogged. The "finger test" is a good way to check: stick your finger into the soil about 2 inches deep. If it feels dry, it's time to water.

During the heat of summer, your bok choy might need up to 1-1.5 inches of water per week, either from rainfall or irrigation. Water at the base of the plants to avoid wetting the leaves, as this can encourage fungal diseases in our low-to-moderate humidity.

Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of organic mulch, like straw or shredded leaves, can help retain soil moisture and keep the soil cooler during hot spells.

You can expect your first harvest of bok choy from early June through early October, depending on when you planted. Baby bok choy is ready to harvest when it reaches 6-8 inches tall, while full-size bok choy can be harvested at 12-15 inches.

To harvest, cut the plant above the base, leaving the roots intact. This allows the plant to regrow and produce more leaves for a continuous harvest. As the first frost approaches in early October, harvest any remaining bok choy, even if it's small. You can blanch and freeze it for later use.

Here are some common problems you might encounter growing bok choy in the Great Plains:

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves. You'll see small dark beetles that jump when disturbed. The worst damage is to young seedlings.
• What causes it: These are small jumping beetles that feed on leaves. They are most damaging to small, young plants, especially during dry spells.
• How to fix/prevent it: Use row covers to protect seedlings during their vulnerable stage. Delay planting until plants are larger. You can also try kaolin clay coating or neem oil spray. Interplanting with basil or catnip can help deter them. Healthy, vigorous plants will often outgrow the damage.

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 hovering around your plants.
• What causes it: These are the larvae of those white cabbage butterflies.
• How to fix/prevent it: Bt spray is very effective. Floating row covers can prevent the butterflies from laying eggs. Handpick the caterpillars when you see them. Interplant with aromatic herbs like thyme or sage, and encourage parasitic wasps.

Slugs

• What it looks like: Irregular holes in leaves, especially on low-growing plants. Silvery slime trails on the leaves and soil are a dead giveaway. Damage is worse at night and in wet weather.
• What causes it: Slugs are gastropods that feed at night in moist conditions. They hide under mulch, boards, and debris during the day.
• How to fix/prevent it: Beer traps (shallow dish of beer sunk into the soil) are effective. Iron phosphate bait is a pet-safe option. Remove any hiding spots. Water in the morning so the soil surface dries out by evening. Copper tape around beds and diatomaceous earth around plants can also help.

Bolting in Heat

• What it looks like: The bok choy sends up a flower stalk. The leaves become tough and bitter, and the harvest quality declines.
• What causes it: This happens when the cool-season crop experiences extended warm temperatures. Bok choy bolts when days consistently exceed 80°F.
• How to fix/prevent it: Time your plantings for cool weather in spring or fall. Choose bolt-resistant varieties. Provide shade during warm spells with shade cloth. Mulch to keep the soil cool. Harvest before the bolting progresses too far.

Great Plains Specific Challenges: Our hot summers and variable rainfall can make it tricky to keep bok choy consistently watered, which can lead to bolting. The strong winds can also damage young plants, so wind protection is essential. Keep a close eye on the weather forecast and be prepared to take action to protect your plants from extreme conditions.

Good companions for bok choy in our Plains gardens include garlic and onions, which help deter pests. Beets are also beneficial, as they don't compete for the same nutrients. Lettuce and spinach make good neighbors, as they have similar growing requirements.

Avoid planting bok choy near strawberries or tomatoes. Strawberries can attract slugs, which will also target your bok choy. Tomatoes can stunt the growth of bok choy, and vice versa. Careful companion planting can help you maximize your yields and minimize pest problems in our challenging climate.