Mustard Greens in Zone 7A — Mid-Atlantic

Mustard greens bring a delightful peppery kick to your Mid-Atlantic garden and plate. They're incredibly versatile – you can sauté them, add them to soups, or even enjoy them raw when the leaves are young. Plus, few things are more satisfying than harvesting your own greens throughout our four distinct seasons.

Our humid summers and occasional temperature swings in spring can present challenges, but with careful timing, you can enjoy a continuous harvest of mustard greens. Our 208-day growing season gives you plenty of opportunity to get this quick-growing crop in the ground.

Starting mustard greens indoors gives you a head start, especially for an early spring crop. You can start seeds indoors from late February through mid March, about three weeks before you plan to transplant them outside. This is most useful if you want an extra-early crop, but direct sowing often works just fine in our moderate Mid-Atlantic spring.

Use seed trays or small pots filled with a good seed-starting mix. Keep the soil consistently moist by bottom watering – set the tray in a shallow dish of water and let the soil soak it up from the bottom. Provide warmth and plenty of light, either from a sunny windowsill or a grow light, until seedlings are ready to move outdoors.

Transplant your mustard greens seedlings outdoors from late March through early May, once the danger 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 sun and wind.

Space the seedlings 6-12 inches apart in well-drained soil. Be mindful of our variable spring weather; watch for late frost warnings and be ready to cover your seedlings if needed.

Direct sowing mustard greens is a simple and effective method, especially for later crops. You can direct sow from early March through early September, taking advantage of our long growing season. Make sure the soil temperature is at least 45°F for good germination.

Prepare the soil by loosening it and removing any rocks or debris. Sow seeds about ½ inch deep and 6-12 inches apart. Keep the soil consistently moist until the seedlings emerge. Direct sowing is less work, but you'll need to protect young plants from pests.

Watering is crucial for healthy mustard greens, especially with our humid summers. Aim to keep the soil consistently moist, but not waterlogged. The "finger test" works well: stick your finger about two inches into the soil, and if it feels dry, it's time to water.

During the hotter months, you'll likely need to water every few days, providing about an inch of water per week. Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our humid climate. In spring and fall, when temperatures are cooler and rainfall is more frequent, you may only need to water once a week or less.

Pay attention to the plants' appearance. Wilting leaves indicate underwatering, while yellowing leaves can be a sign of overwatering. A layer of mulch, like straw or shredded leaves, can help retain moisture and regulate soil temperature, which is a huge help during our summer heat.

You can expect your first harvest of mustard greens from late April through early November, depending on when you planted. Mustard greens are typically ready to harvest about 45 days after planting. Young leaves have a milder flavor and are great for salads, while larger leaves are spicier and better for cooking.

Harvest by cutting individual leaves from the outer part of the plant, leaving the inner leaves to continue growing. This allows for continuous production throughout the season. Be sure to harvest before the plant starts to flower, as this can make the leaves bitter.

As our first frost approaches in late October, harvest any remaining leaves to enjoy before the cold weather sets in. You can also cover the plants with a frost blanket to extend the harvest a bit longer.

Here are some common problems you might encounter growing mustard greens in the Mid-Atlantic:

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves, especially on young seedlings. Small dark beetles that jump when disturbed.
• What causes it: These small jumping beetles feed on the leaves, and they're most damaging to small, young plants.
• How to fix/prevent it: Use row covers to protect seedlings during their vulnerable stage. You can also delay planting until plants are larger and more resistant. A coating of kaolin clay can deter them, and neem oil spray can help control infestations. Interplanting with basil or catnip may also help.

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) on stems and leaf undersides. Sticky honeydew residue and curled or distorted new growth.
• What causes it: These sap-sucking insects reproduce rapidly, especially in warm weather. Ant colonies may farm them for honeydew.
• How to fix/prevent it: A strong spray of water can knock them off. Encourage natural predators like ladybugs and lacewings. Use insecticidal soap for heavy infestations, and neem oil can work systemically. Avoid excess nitrogen fertilizer, which attracts them.

Cabbage Worms

• What it looks like: Smooth green caterpillars on brassica leaves. Irregular holes chewed in leaves, dark green droppings, and white butterflies hovering around plants.
• What causes it: These are the larvae of white cabbage butterflies, and they can have multiple generations per season in our warm climate.
• How to fix/prevent it: Bt spray is very effective. Floating row covers can prevent the butterflies from laying eggs. Handpick caterpillars when you see them. Interplant with aromatic herbs like thyme and sage, and encourage parasitic wasps.

Bolting in Heat

• What it looks like: The plant sends up a flower stalk, and the leaves become tough and bitter.
• What causes it: Mustard greens are a cool-season crop and will bolt when temperatures rise. This often happens when days consistently exceed 80°F.
• How to fix/prevent it: Time your plantings for cool weather in spring and fall. Choose bolt-resistant varieties. Provide shade during warm spells, and mulch to keep the soil cool. Harvest before bolting progresses.

Mid-Atlantic Specific Challenges: Our moderate-to-hot summers and humid conditions can make mustard greens more susceptible to bolting and fungal diseases. Consistent monitoring and prompt action are key to keeping your plants healthy. The even rainfall helps, but you still need to water deeply during dry spells.

Mustard greens thrive with certain companions in the Mid-Atlantic garden. Onions and garlic are great choices, as their pungent scent can deter pests like aphids and flea beetles. Beets are also beneficial, as they don't compete for the same nutrients and can help improve soil structure. Dill attracts beneficial insects like ladybugs and lacewings, which prey on aphids. Lettuce makes a good ground cover, helping to keep the soil cool and moist.

Avoid planting mustard greens near strawberries or tomatoes. Strawberries are susceptible to some of the same fungal diseases as mustard greens, and planting them together can increase the risk of infection. Tomatoes can stunt the growth of mustard greens, possibly due to allelopathic compounds they release into the soil.