Mustard Greens in Zone 7A — Southeast

Mustard greens are a fantastic addition to any Southeastern garden. They bring a zesty, peppery flavor to your table, whether you're adding them to salads, stir-fries, or braising them Southern-style. Plus, with our long growing season, you can enjoy multiple harvests of this nutritious green from spring through fall.

While the Southeast's hot and humid summers can present challenges like increased disease pressure and bolting, careful timing and variety selection will help you overcome these issues. Our 225-day growing season gives you plenty of opportunities to plant and harvest mustard greens.

Starting mustard greens indoors is definitely an option, especially if you're aiming for an extra-early spring harvest or want to get a jump start on the season. Start your seeds indoors from mid-February through early March, roughly three weeks before you plan to transplant them outside. Use seed trays 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 your friend for seed starting. It helps prevent damping-off disease. Just set the tray in a shallow container of water until the soil surface is moist.

Keep in mind that our springs can be moderate here, so starting indoors offers a bit of insurance against any late cold snaps. However, mustard greens germinate easily, so direct sowing is also a perfectly viable choice.

Transplant your mustard green seedlings outdoors from mid-March through late April, once the soil has warmed up a bit and the danger of a hard frost has passed. Before transplanting, harden off your seedlings by gradually exposing them to outdoor conditions for about a week. Start with an hour or two of sunlight and increase the time each day.

Space your plants 6-12 inches apart to allow for good air circulation, which helps prevent fungal diseases in our humid climate. Keep an eye out for late-season frosts, which can still occur during this period.

Direct sowing mustard greens is a simple and effective method, especially for succession planting throughout the growing season. You can direct sow from late February through early September, giving you a long window to get your seeds in the ground. Choose a spot with well-drained soil, and work in some compost or other organic matter before planting.

Sow seeds about ½ inch deep and keep the soil consistently moist until they germinate. Thin seedlings to 6-12 inches apart once they emerge. Direct sowing works best when the soil temperature is consistently above 45°F.

Mustard greens need consistent moisture to thrive, but overwatering can lead to problems in our humid Southeast climate. Aim to keep the soil consistently moist, but not soggy. The finger test is a good way to gauge moisture levels: stick your finger about 2 inches into the soil; if it feels dry, it's time to water.

During the spring and fall, when temperatures are cooler and rainfall is more frequent, you may only need to water once or twice a week. In the heat of summer, especially if we're experiencing a dry spell, you might need to water every other day. Even though we often get afternoon thunderstorms, don't rely on them to provide all the water your plants need.

Water at the base of the plants to avoid wetting the leaves, which can encourage fungal diseases in our humid environment. Aim for about 1 inch of water per week, either from rainfall or irrigation. Signs of underwatering include wilting leaves and slow growth. Overwatering can lead to yellowing leaves and root rot. A layer of mulch around your mustard greens will help retain moisture and suppress weeds. Pine straw or shredded leaves work well here in the Southeast.

You can expect your first harvest of mustard greens around mid-April if you started early, and you can continue harvesting all the way through mid-November. Mustard greens are ready to harvest about 45 days after planting. Harvest young leaves when they are about 4-6 inches long for a milder flavor. Larger, more mature leaves will have a spicier kick.

Pick the outer leaves, leaving the inner leaves to continue growing. This cut-and-come-again method allows for continuous harvests throughout the season. Be sure to harvest before the plant starts to flower (bolt), as the leaves will become bitter and tough.

As the first frost approaches in early November, harvest any remaining leaves to enjoy before the cold weather sets in. You might even get a few more harvests if you protect the plants with a cold frame or row cover.

Here are some common issues you might encounter growing mustard greens in the Southeast:

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves, especially on young seedlings. You'll see 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. They love warm, dry weather, so they can be a real nuisance in the spring.
• How to fix/prevent it: Cover seedlings with row covers to protect them during their vulnerable stage. You can also delay planting until plants are larger and more resilient. Kaolin clay coating can deter them. Neem oil spray can help control infestations. Interplant with basil or catnip. Healthy, vigorous 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. You might also notice a sticky honeydew residue and curled or distorted new growth.
• What causes it: Aphids are rapid-reproducing sap-sucking insects. Populations explode in warm weather, and ant colonies often farm them for honeydew.
• How to fix/prevent it: A strong water spray can knock them off. Encourage ladybugs and lacewings (natural predators). Insecticidal soap can be used for heavy infestations. Neem oil works systemically. Avoid excess nitrogen fertilizer, as it attracts them.

Cabbage Worms

• What it looks like: Smooth green caterpillars on brassica leaves. You'll see irregular holes chewed in the leaves, and dark green droppings. White butterflies hovering around plants are a sign.
• What causes it: These are the larvae of white cabbage butterflies. We often have multiple generations per season in our warm climate.
• How to fix/prevent it: Bt (Bacillus thuringiensis) spray is very effective. Floating row covers can prevent egg laying. Handpick caterpillars when you see them. Interplant with aromatic herbs like thyme or sage. Encourage parasitic wasps.

Bolting in Heat

• What it looks like: The plant sends up a flower stalk, and the leaves become tough and bitter. The harvest quality declines.
• What causes it: Mustard greens are a cool-season crop, and they bolt when temperatures rise. This is especially common during our hot summers.
• How to fix/prevent it: Time your plantings for cooler weather in spring and fall. Choose bolt-resistant varieties. Provide shade during warm spells. Mulch to keep the soil cool. Harvest before bolting progresses too far.

Southeast Specific Challenges: Our hot, humid summers create a perfect environment for fungal diseases. Good air circulation and proper watering practices are essential. Japanese beetles can also be a nuisance, so keep an eye out for them and take action if needed. Deer can also be a problem, so consider fencing or other deterrents if they are common in your area. Our clay soil can be challenging, so amend it with plenty of organic matter to improve drainage and fertility.

Companion planting can be a great way to improve the health and productivity of your mustard greens. Onions and garlic are excellent companions because their strong scent can help deter pests like aphids and flea beetles. Beets are also good companions, as they don't compete for the same nutrients and can help loosen the soil. Dill attracts beneficial insects like ladybugs and lacewings, which prey on aphids and other pests. Lettuce makes a good ground cover, suppressing weeds and keeping the soil cool.

Avoid planting mustard greens near strawberries or tomatoes. Strawberries are susceptible to fungal diseases that can spread to mustard greens in our humid climate. Tomatoes compete for the same nutrients and can shade out the mustard greens, especially in the long summer.