Bok Choy in Zone 7B — Pacific Northwest

Bok Choy is a fantastic addition to any Pacific Northwest garden. Its mild, slightly sweet flavor shines in stir-fries, soups, and salads, and it's incredibly versatile in the kitchen. Here in the PNW, the cool nights and mild summers actually enhance the flavor of your bok choy, making it even more delicious.

While we PNW gardeners might struggle with heat-loving plants, Bok Choy thrives in our climate, especially with the long, mild fall. Our 193-day growing season gives you plenty of time to get multiple harvests. Careful timing will help you avoid any potential issues.

Starting Bok Choy indoors is possible, but honestly, it's not always necessary here in the PNW. Our springs are long enough to direct sow. Indoor starts are most helpful if you're aiming for a very early spring harvest.

If you do start indoors, aim for mid-March through early April, about four weeks before you want to transplant. Use seed trays with a good seed-starting mix. Keep them warm and provide plenty of light – a grow light is helpful since our overcast spring days can be dim. Bottom watering helps prevent damping-off; just set the tray in a shallow dish of water until the soil surface is moist.

Transplanting Bok Choy seedlings outdoors can be done from mid-April through late May. Before you transplant, be sure to harden off your seedlings. This means gradually exposing them to outdoor conditions for about a week.

Space the plants 6-10 inches apart in well-drained soil. Keep an eye on the weather forecast; a late frost can still happen in April, so be prepared to cover your seedlings if necessary. The cool soil in spring can slow growth at first, so be patient.

Direct sowing Bok Choy is a great option in the Pacific Northwest, especially for succession planting. You can direct sow from early April through late August. This gives you a long window for multiple harvests.

Prepare the soil by loosening it and adding compost. Bok Choy prefers a soil temperature of at least 50°F for germination. Sow seeds about ½ inch deep and 6-10 inches apart. Thin seedlings as needed once they emerge.

Consistent moisture is key for happy Bok Choy in the Pacific Northwest. While our mild summers mean we rarely see temperatures above 90°F, dry spells can still happen. Bok Choy bolts quickly in dry or hot conditions, so don't let it dry out.

During the wet springs, you might not need to water much at all – let the rain do the work. In the drier summer months, check the soil moisture regularly. Stick your finger about 2 inches deep; if it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation. 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 yellowing leaves and root rot. A layer of mulch, like straw or wood chips, can help retain moisture and keep the soil cool.

You can expect your first Bok Choy harvest from mid-May through early November in the Pacific Northwest. Bok Choy is ready to harvest about 45 days after planting. You can harvest baby bok choy when it's 6-8 inches tall, or wait for full size 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. Keep harvesting regularly to encourage new growth.

As the first frost approaches in late October, harvest any remaining Bok Choy. Even though it's semi-hardy, a hard frost can damage the leaves. You can also try covering the 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 Pacific Northwest:

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in the leaves, especially on young seedlings. You might see small, dark beetles that jump when disturbed.
• What causes it: Small jumping beetles that feed on the leaves. They're most damaging to small, young plants in the spring.
• How to fix/prevent it: Row covers are your best bet to protect seedlings. You can also delay planting until the plants are larger and more resilient. Kaolin clay coating or neem oil spray can also help. Interplanting with basil or catnip can 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: The larvae of white cabbage butterflies.
• How to fix/prevent it: Bt spray is very effective. Floating row covers prevent the butterflies from laying eggs. Handpicking the caterpillars is also an option. Interplant with aromatic herbs like thyme or sage to deter the butterflies.

Slugs

• What it looks like: Irregular holes in the leaves, especially on low-growing plants. You'll also see silvery slime trails on the leaves and soil. Damage is worse at night and in wet weather.
• What causes it: Gastropods that feed at night in moist conditions. They thrive in our wet springs and hide under mulch 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 hiding spots like boards 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 above the plant's comfort zone. Bok Choy bolts when days consistently exceed 80°F.
• How to fix/prevent it: Time your plantings for cool weather (spring/fall). Choose bolt-resistant varieties. Provide shade during warm spells. Mulch to keep the soil cool. Harvest before bolting progresses too far.

Pacific Northwest Specific Challenges: Our mild heat and dry-summer rainfall mean that bolting and flea beetles are the biggest concerns. Pay attention to the weather forecast and be prepared to provide shade and protection if needed. Slugs are always a threat in our damp climate, so take preventative measures early. Late blight isn't a direct threat to Bok Choy, but practicing good garden hygiene helps prevent it from spreading to other susceptible plants.

Good companions for Bok Choy include garlic and onion, which deter pests like aphids and cabbage worms. Beets and lettuce are also good companions because they don't compete for the same nutrients and can help shade the soil, keeping it cool. Spinach is another great choice because it grows quickly and provides ground cover, suppressing weeds.

Avoid planting Bok Choy near strawberries, as they can attract slugs, which will then feast on your Bok Choy. Tomatoes are also not ideal companions, as they are heavy feeders and can compete for nutrients.