Bok Choy in Zone 7A — Pacific Northwest

Bok Choy is a fantastic addition to any Pacific Northwest garden. Its mild, slightly sweet flavor shines in stir-fries, soups, and even salads. Plus, the cool nights we often get here in the PNW seem to make it even more crisp and delicious.

While our wet springs and mild summers can present some challenges, Bok Choy thrives with proper timing. Our long 183-day growing season gives you plenty of opportunity to plant multiple crops. You can easily work around potential issues like bolting in warmer weather.

Starting Bok Choy indoors is possible, but honestly, it's often not necessary here in the PNW unless you're aiming for a very early harvest. If you want a head start, begin in mid-March through early April, about four weeks before the last expected frost. Use seed trays with a good seed-starting mix and provide consistent warmth and light.

Bottom watering is a great way to keep the seedlings evenly moist without overwatering. It's especially helpful during those overcast spring days we get so often. But keep in mind that direct sowing is usually successful and saves you the indoor space.

Transplant your Bok Choy seedlings outdoors from mid-April through early June. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the cooler temperatures and stronger sunlight.

Space the seedlings 6-10 inches apart to allow for good air circulation. Be mindful of potential late frosts that can still occur during this period. If a frost is predicted, cover the young plants with row covers or blankets.

Direct sowing Bok Choy is a simple and effective method here in the PNW. Sow seeds from early April through late August for a continuous harvest. Choose a spot with full sun to partial shade and prepare the soil by loosening it and adding compost.

Sow seeds 1/4 to 1/2 inch deep and space them 6-10 inches apart. Keep the soil consistently moist, especially during germination. Direct sowing is best when the soil has warmed up a bit, usually by late spring.

Bok Choy needs consistent moisture, especially during our dry summer months. Aim to keep the soil evenly moist, but not waterlogged. During the wetter spring, you may not need to water at all, but once our dry summers hit, you'll need to be more diligent.

Stick your finger about two inches deep into the soil. If it feels dry, it's time to water. Generally, Bok Choy needs about 1 inch of water per week, either from rainfall or irrigation. Water at the base of the plant to avoid wetting the leaves, which can encourage fungal diseases in our humid environment.

Overwatering can lead to root rot, while underwatering can cause bolting. Signs of underwatering include wilting leaves and slow growth. Yellowing leaves can indicate overwatering. A layer of mulch will help retain moisture and keep the soil cool.

You can expect your first Bok Choy harvest from late May through late October, depending on when you planted. Baby Bok Choy can be harvested when it's 6-8 inches tall, while full-sized heads are ready at 12-15 inches. Look for firm, compact heads with healthy-looking leaves.

To harvest, cut the Bok Choy just above the base of the plant. This allows for potential regrowth and a second harvest. You can also harvest individual outer leaves as needed. As our first frost approaches in mid-October, harvest any remaining Bok Choy to prevent damage.

Here are some common problems you might encounter growing Bok Choy in the Pacific Northwest:

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.
• How to fix/prevent it: Use row covers to protect seedlings. Delay planting until plants are larger. You can also try a kaolin clay coating or neem oil spray. 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 hovering around your plants.
• What causes it: These are the larvae of white cabbage butterflies.
• How to fix/prevent it: Bt spray is very effective. Floating row covers prevent egg laying. You can also handpick caterpillars and interplant with aromatic herbs like thyme and sage.

Slugs

• What it looks like: Irregular holes in leaves, especially low-growing plants. You'll often see silvery slime trails on leaves and soil. Damage is usually worse at night and in wet weather.
• What causes it: Slugs thrive in our moist PNW climate.
• How to fix/prevent it: Beer traps (shallow dish of beer sunk into soil) are effective. Iron phosphate bait is pet-safe. Remove hiding spots like mulch and debris. Water in the morning so the soil surface dries by evening. Copper tape around beds and 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: Extended warm temperatures, which can happen even during our mild summers.
• How to fix/prevent it: Time your plantings for cooler weather (spring/fall). Choose bolt-resistant varieties. Provide shade during warm spells, and mulch to keep the soil cool. Harvest before bolting progresses too far.

Pacific Northwest Specific Challenges: Our mild summers and dry-summer humidity can make bolting a concern, so choose bolt-resistant varieties and provide shade during warmer periods. Slugs are always a challenge in the PNW, so stay vigilant with your control methods. Late blight is typically a problem for tomatoes and potatoes, but it's good to maintain good air circulation to prevent any fungal issues.

Good companions for Bok Choy include garlic and onions, as their strong scent can deter pests. Beets improve soil health, and lettuce and spinach offer ground cover to suppress weeds. Avoid planting Bok Choy near strawberries or tomatoes. Strawberries compete for nutrients, and tomatoes are susceptible to late blight, which can spread to Bok Choy.