Mustard Greens in Zone 6B — Midwest

Mustard greens are a fantastic addition to any Midwest garden, offering a spicy kick to salads and cooked dishes. They thrive in our fertile soil and provide a delicious harvest from spring through fall. You can enjoy them fresh or cooked, adding a unique flavor to your meals.

While our Midwest weather can be unpredictable, with variable springs and summer heat spells, mustard greens are surprisingly resilient. Our long 183-day growing season gives you plenty of opportunities to plant and harvest this flavorful green. With a little planning, you can enjoy a continuous supply of mustard greens throughout the season.

Starting mustard greens indoors is definitely an option, especially if you want a head start on the season. Starting seeds indoors during early to late March gives you a jump, about 3 weeks before you'd consider transplanting. This can be helpful in our region, where spring can be moderate-to-late.

Use seed trays or small pots filled with a good seed-starting mix. Keep them warm and provide plenty of light – a grow light works wonders. Don’t forget to water from the bottom to prevent damping-off. Honestly, though, with our long growing season, direct sowing often works just as well, saving you some effort.

Transplanting your mustard greens seedlings outdoors can be done from early April through mid May. Before you move them permanently, be sure to harden them off. This means gradually exposing them to outdoor conditions for about a week.

When transplanting, space the seedlings 6-12 inches apart to give them room to grow. Keep an eye on the weather, since we can still get a late frost in early spring. If frost threatens, cover the seedlings with row covers or blankets.

Direct sowing mustard greens is super easy and often the preferred method for many Midwest gardeners. You can sow seeds directly into the garden from mid March through mid August. This gives you a long window for multiple plantings and continuous harvests.

Prepare the soil by loosening it and removing any rocks or debris. Mustard greens prefer soil temperatures between 45°F and 75°F for optimal germination. Sow seeds about ½ inch deep and space them 6-12 inches apart, or sow more densely and thin later.

Consistent watering is key to happy mustard greens, especially with our moderate-to-hot summer heat. While we get a fair amount of wet-summer rainfall (30-40 inches annually), you'll still need to supplement during drier periods. Mustard greens aren't drought-tolerant, and stressing them can lead to bitter leaves and bolting.

Aim to keep the soil consistently moist but not soggy. A good way to check is the "finger test" – stick your finger about 2 inches into the soil. If it feels dry, it's time to water. During the warmer months, your mustard greens may need about 1 inch of water per week.

Water at the base of the plants to avoid wetting the leaves, especially with our moderate-to-humid conditions. Wet leaves can encourage fungal diseases. Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. Consider mulching around your plants to help retain moisture and keep the soil cool, especially during summer heat spells.

You can expect your first harvest of mustard greens from early May through late October, depending on when you planted. Mustard greens are typically ready to harvest about 45 days after planting. The leaves are ready when they're a good size, usually around 6-8 inches long.

Harvest young leaves for a milder flavor, and larger leaves for a spicier kick. Be sure to pick the leaves before the plant starts to flower, as this can make them bitter. To harvest, simply snip off the outer leaves with scissors or a knife, leaving the inner leaves to continue growing.

This cut-and-come-again method encourages continued production throughout the season. As our first frost approaches in mid- October, harvest any remaining leaves to enjoy before the cold weather sets in. You can also cover the plants to extend the harvest a bit longer.

Mustard greens, like any garden crop, can face a few challenges in the Midwest. Here are some common problems and how to deal with them:

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves. Small dark beetles that jump when disturbed. Worst damage to young seedlings.
• What causes it: Small jumping beetles that feed on leaves. They are most damaging to small, young plants.
• How to fix/prevent it: Row covers protect seedlings. Delay planting until plants are larger. You can also try kaolin clay coating or neem oil spray. Interplant with basil or catnip. Healthy plants often outgrow the damage.

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue. Curled or distorted new growth.
• What causes it: Rapid-reproducing sap-sucking insects. Populations explode in warm weather. Ant colonies may farm them.
• How to fix/prevent it: Strong water spray knocks them off. Encourage ladybugs and lacewings. Use insecticidal soap for heavy infestations. Neem oil works systemically. Avoid excess nitrogen fertilizer.

Cabbage Worms

• What it looks like: Smooth green caterpillars on brassica leaves. Irregular holes chewed in leaves. Dark green droppings. White butterflies hovering around plants.
• What causes it: Larvae of white cabbage butterflies. Multiple generations per season in warm climates.
• How to fix/prevent it: Bt spray is very effective. Floating row covers prevent egg laying. Handpick caterpillars. Interplant with aromatic herbs (thyme, sage). Encourage parasitic wasps.

Bolting in Heat

• What it looks like: The plant sends up a flower stalk. Leaves become tough and bitter. Harvest quality declines.
• What causes it: Extended warm temperatures. Mustard greens bolt when days consistently exceed 80°F.
• How to fix/prevent it: Time plantings for cool weather (spring/fall). Choose bolt-resistant varieties. Provide shade during warm spells. Mulch to keep soil cool. Harvest before bolting progresses.

Midwest Specific Challenges: Our moderate-to-hot summer heat and moderate-to-humid humidity can create conditions that favor pests like aphids and flea beetles, and can also trigger bolting. Regular monitoring and proactive measures are key to keeping your mustard greens healthy and productive.

Companion planting can really boost your mustard greens' growth and health. Onions and garlic are great companions because their strong scent deters pests like aphids and cabbage moths. Beets are also beneficial, as they help loosen the soil, making it easier for mustard greens to grow.

Dill is another good choice, attracting beneficial insects like ladybugs and lacewings that prey on aphids. Lettuce can provide ground cover, helping to keep the soil cool and moist. Avoid planting mustard greens near strawberries or tomatoes. Strawberries are susceptible to similar fungal diseases, and tomatoes can stunt the growth of mustard greens.