Bok Choy in Zone 6B — Midwest

Bok choy is a fantastic addition to any Midwest garden. It's a fast-growing green that thrives in our fertile soil and delivers a mild, slightly sweet flavor perfect for stir-fries, soups, or even just a quick sauté. Plus, harvesting your own fresh bok choy, even if it's just a small patch, brings a unique satisfaction.

Our Midwest weather can be a bit unpredictable, with those summer heat spells and variable springs. But don't worry, bok choy is surprisingly adaptable. With a little planning, you can easily squeeze in a couple of harvests during our 183-day growing season.

Starting bok choy indoors in the Midwest isn't always necessary, but it can give you a head start, especially for an early spring harvest. If you're aiming for that, begin around mid-March through early April, about four weeks before you plan to transplant. This helps you get a jump on the season, given our moderate-to-late spring.

Use seed trays filled with a good seed-starting mix and keep them in a warm spot with plenty of light – a sunny windowsill or under grow lights works well. Bottom watering is key to prevent damping off; just set the tray in a shallow dish of water until the soil surface is moist.

Transplanting your bok choy seedlings outdoors should happen around mid-April through late May, once the risk of a hard frost has passed. Remember, we often get a little temperature swing in early spring, so watch for late frost. Before planting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

When transplanting, space the plants about 6-10 inches apart. If we get a sudden cold snap, be ready to cover your young plants with a frost blanket for a few nights, since those tender leaves can be vulnerable.

Direct sowing bok choy is a great option in the Midwest, and it's often the easiest way to go. You can sow seeds directly into the garden from early April through mid August. This gives you flexibility for multiple harvests.

Make sure the soil is well-worked and the soil temperature is at least 50°F. Sow seeds about a quarter-inch deep and space them 6-10 inches apart. Thin the seedlings to the strongest plants once they emerge. Direct sowing avoids transplant shock, but you'll need to watch for pests early on.

Bok choy needs consistent moisture, especially in our Midwest summers. It's not drought-tolerant and will bolt quickly if it dries out, especially when we get those summer heat spells. Aim to keep the soil evenly moist, not soggy.

A good rule of thumb is to water deeply about once or twice a week, providing about 1 inch of water each time. Stick your finger about 2 inches into the soil; if it feels dry, it's time to water. Since we often have moderate-to-humid conditions, water at the base of the plants rather than overhead to minimize fungal diseases.

If the leaves are wilting, that’s a sign of underwatering. Yellowing leaves can indicate overwatering. Applying a layer of mulch, like straw or shredded leaves, will help retain moisture and keep the soil cool, which is especially helpful during our warmer months.

You can expect your first harvest of bok choy around mid-May through late October in the Midwest, depending on when you planted. Bok choy is usually ready to harvest about 45 days after planting. You can harvest baby bok choy when the leaves are about 6-8 inches tall, or wait for the full-size heads to reach 12-15 inches.

To harvest, cut the entire head above the base, leaving the roots intact. This encourages regrowth for a second harvest. As our first frost approaches around mid- October, harvest any remaining bok choy, even if it's small. It won’t survive a hard freeze.

Here are some common problems you might encounter with bok choy in the Midwest:

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 are small jumping beetles that feed on the leaves. They are most damaging to small, young plants, which is a concern in our variable spring weather.
• How to fix/prevent it: Use row covers to protect seedlings. Delay planting until plants are larger. You can also try spraying with neem oil or interplanting with basil or catnip.

Cabbage Worms

• What it looks like: Smooth green caterpillars on the leaves, irregular holes chewed in the leaves, dark green droppings. You might see white butterflies fluttering around your plants.
• What causes it: These are the larvae of white cabbage butterflies. They thrive in our moderate-to-hot summers.
• How to fix/prevent it: Bt spray is very effective. Use floating row covers to prevent the butterflies from laying eggs. Handpick the caterpillars when you see them. Interplant with aromatic herbs like thyme or sage.

Slugs

• What it looks like: Irregular holes in leaves, especially on low-growing plants. Silvery slime trails on leaves and soil. Damage is worse at night and in wet weather.
• What causes it: Slugs thrive in moist conditions, which we often get with our wet-summer rainfall.
• How to fix/prevent it: Use beer traps (shallow dish of beer sunk into the soil). Iron phosphate bait is also effective and pet-safe. Remove any hiding spots like mulch or boards. Water in the morning so the soil surface dries out by evening. Copper tape around the beds can also deter slugs.

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 it bolts when temperatures rise consistently above 80°F. Our summer heat spells can definitely trigger bolting.
• How to fix/prevent it: Time your plantings for cool weather in spring and fall. Choose bolt-resistant varieties. Provide shade during warm spells. Mulch to keep the soil cool. Harvest the bok choy before bolting progresses too far.

Midwest Specific Challenges: The moderate-to-hot heat and moderate-to-humid humidity of our Midwest summers can create favorable conditions for pests like cabbage worms and slugs, and can also cause bolting. Watch your plants closely and take preventative measures to keep them healthy and productive.

Companion planting can really help your bok choy thrive in the Midwest garden. Garlic and onions are great companions because their strong scent can deter pests like flea beetles and cabbage worms. Beets are also helpful, as they don't compete for the same nutrients and can improve soil structure.

Lettuce and spinach make good ground cover, helping to keep the soil cool and moist, which is especially beneficial during our summer heat spells. Avoid planting bok choy near strawberries or tomatoes, as they can attract similar pests or compete for resources, hindering the growth of your bok choy.