Mustard Greens in Zone 7A — Northeast

Mustard greens offer a spicy kick to your salads and stir-fries, and they're surprisingly easy to grow in our Northeast gardens. The cool nights we often get, even in summer, actually enhance their flavor, making them a rewarding addition to your garden.

Our short growing season and the occasional late or early frost can be a challenge, but with a little planning, you can enjoy a continuous harvest of mustard greens. Our 198-day growing season gives you plenty of time to get multiple crops in.

Starting mustard greens indoors gives you a head start, but it's not essential. If you're eager for an extra-early crop, start seeds indoors from late February through mid March, about 3 weeks before you plan to transplant.

Use seed trays with a good seed-starting mix, and keep them in a warm spot with plenty of light. Bottom watering helps prevent damping-off, a common issue, especially with our sometimes-damp spring weather. Remember that spring can be late here, so don't rush them outside too soon.

Transplant your mustard greens outdoors from late March through early May. Before planting, harden them off by gradually exposing them to outdoor conditions for about a week.

Space the plants 6-12 inches apart. Keep an eye on the forecast; we can still get a frost in late March or early April, so be ready to cover them if needed.

Direct sowing mustard greens is very straightforward, and it's a great option for successive plantings throughout the growing season. You can direct sow from mid March through late August.

Prepare the soil by loosening it and removing any rocks – we all know about our rocky New England soil. Sow seeds 1/4 inch deep, and keep the soil consistently moist. Direct sowing avoids transplant shock, but the young seedlings are more vulnerable to pests.

Mustard greens need consistent moisture to thrive, but avoid waterlogging the soil. In our Northeast climate, the key is to find the right balance, especially with our even rainfall.

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 warmer summer months, especially during dry spells, increase watering to two or three times a week. Stick your finger about 2 inches deep into the soil; 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 in our moderately humid climate. Wilting leaves indicate underwatering, while yellowing leaves can be a sign of overwatering. A light layer of mulch, like straw or shredded leaves, helps retain moisture and suppress weeds.

You can expect your first harvest of mustard greens from late April through early November, about 45 days after planting. Young leaves, about 4-6 inches long, have a milder flavor and are great for salads.

Harvest by snipping off the outer leaves, leaving the inner leaves to continue growing. This allows for continuous production throughout the season. As the first frost approaches in late October, harvest any remaining leaves, as they may become damaged by the cold.

Here are some common issues you might encounter with mustard greens in the Northeast:

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 small jumping beetles feed on the leaves, and they're most active in spring.
• How to fix/prevent it: Use row covers to protect seedlings. You can also try spraying with neem oil or kaolin clay. Interplanting with basil or catnip can help deter them.

Aphids

• What it looks like: Clusters of tiny green, black, or white insects on stems and leaf undersides. You might also notice sticky honeydew residue and curled or distorted new growth.
• What causes it: These sap-sucking insects multiply rapidly, especially in warm weather.
• How to fix/prevent it: Knock them off with a strong spray of water. Encourage ladybugs and lacewings, which are natural predators. Insecticidal soap can also be effective.

Cabbage Worms

• What it looks like: Smooth green caterpillars chewing irregular holes in the leaves. You might also see dark green droppings and white butterflies fluttering around your plants.
• What causes it: These are the larvae of cabbage butterflies.
• How to fix/prevent it: Bt spray is very effective. You can also use floating row covers to prevent the butterflies from laying eggs. Handpicking the caterpillars is another option.

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 they bolt (go to seed) when temperatures rise.
• How to fix/prevent it: Time your plantings for spring or fall. Choose bolt-resistant varieties. Provide shade during warm spells.

Northeast Specific Challenges: Our moderate heat and moderate-to-humid humidity means you have to be vigilant about watering and pest control. The even rainfall helps, but be ready to irrigate during dry spells.

Good companions for mustard greens include onions and garlic, which deter pests. Beets improve soil health and don't compete for nutrients. Dill attracts beneficial insects that prey on aphids and cabbage worms. Lettuce provides ground cover and helps retain moisture. Avoid planting mustard greens near strawberries, as they can attract pests that affect both crops, and tomatoes, which require different soil conditions.