Mustard Greens in Zone 5A — Midwest

Mustard greens are a fantastic addition to any Midwest garden. Their peppery bite adds zing to salads and stir-fries, plus they're incredibly easy to grow in our fertile soil. You'll get a lot of satisfaction harvesting fresh greens throughout the growing season, especially knowing you grew them yourself.

Our Midwest weather can be unpredictable, with variable springs and summer heat spells, but mustard greens are surprisingly resilient. With a 157-day growing season, we have plenty of time to get multiple harvests if we time things right.

Starting mustard greens indoors isn't essential, but it can give you a head start, especially if you're itching to get gardening during those late winter months. You can start seeds indoors from mid-March through early April, about 3 weeks before you'd like to transplant them outside.

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. Water from the bottom to avoid damping off. Given our moderate-to-late springs, indoor starting allows you to get a jump on the season.

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

Plant them 6-12 inches apart in well-drained soil. Keep an eye on the weather forecast, since we can still get a late frost in April. A row cover can protect your young plants if needed.

Direct sowing mustard greens is a simple and effective method for Midwest gardeners. You can sow seeds directly into the garden from early April through early August.

Prepare the soil by loosening it and adding some compost. Make sure the soil temperature is at least 45°F. Sow seeds about ½ inch deep and 6-12 inches apart. Direct sowing is less work upfront, but you'll need to stay on top of weeding.

Mustard greens need consistent moisture, especially during our moderate-to-hot summer heat spells. Aim to keep the soil consistently moist, but not waterlogged. Drought stress will make the leaves spicier and can cause the plants to bolt prematurely.

During the spring and fall, when temperatures are cooler and we tend to get more rainfall, you might only need to water once or twice a week. In the heat of summer, especially during dry spells, you may need to water daily. Use the finger test – 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. Watering at the base of the plants is best, to avoid getting the leaves wet, which can encourage fungal diseases in our moderate-to-humid climate.

If the leaves are wilting or turning yellow, you're likely underwatering. If the leaves are yellowing and the soil is constantly soggy, you're overwatering. A layer of mulch, like straw or shredded leaves, will help retain moisture and keep the soil cool.

You can expect your first harvest of mustard greens from mid-May through mid-October, depending on when you planted. Mustard greens are typically ready to harvest about 45 days after planting.

Harvest young leaves when they're about 4-6 inches long for a milder flavor. Larger leaves will be spicier. Simply snip off the outer leaves, leaving the inner leaves to continue growing. This encourages continued production throughout the season.

As the first frost approaches in early October, harvest any remaining leaves, even if they're small. You can use them in a final stir-fry or soup.

Here are some common problems you might encounter growing mustard greens in the Midwest:

Flea Beetles

• What it looks like: Tiny round holes (shot-hole pattern) in leaves. You'll see small dark beetles that jump when disturbed. Young seedlings are most vulnerable.
• What causes it: These small jumping beetles feed on the leaves. They thrive in warm, dry conditions.
• How to fix/prevent it: Row covers are your best bet to protect seedlings. Delay planting until plants are larger. You can also try spraying with kaolin clay or neem oil. Interplanting with basil or catnip can help deter them.

Aphids

• What it looks like: Clusters of tiny soft-bodied insects (green, black, or white) on stems and leaf undersides. You might also see sticky honeydew residue and curled or distorted new growth.
• What causes it: These sap-sucking insects reproduce rapidly, especially in warm weather.
• How to fix/prevent it: A strong spray of water will knock them off. Encourage natural predators like ladybugs and lacewings. Insecticidal soap or neem oil can help with heavy infestations. Avoid over-fertilizing with nitrogen, as this attracts them.

Cabbage Worms

• What it looks like: Smooth green caterpillars on the leaves. You'll see irregular holes chewed in the leaves and dark green droppings. White butterflies hovering around the plants are a telltale sign.
• What causes it: These are the larvae of those white cabbage butterflies. They can have multiple generations per season in our climate.
• How to fix/prevent it: Bt spray is very effective. Floating row covers will prevent the butterflies from laying eggs. Handpicking the caterpillars is also an option. Interplant with aromatic herbs like thyme or sage to deter them.

Bolting in Heat

• What it looks like: The plant sends up a flower stalk. The leaves become tough and bitter.
• What causes it: Mustard greens are a cool-season crop and will bolt (go to seed) when temperatures rise consistently above 80°F. This is common during our summer heat spells.
• 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 leaves frequently to delay bolting.

Midwest Specific Challenges: Our moderate-to-hot summers and moderate-to-humid humidity can create ideal conditions for pests and diseases. Be vigilant about monitoring your plants and take action quickly to prevent problems from getting out of hand. The wet-summer rainfall can also contribute to fungal diseases, so ensure good air circulation and avoid overhead watering whenever possible.

Companion planting can really boost your mustard greens in the Midwest. Onions and garlic are great companions because their strong scent deters many pests. Beets are also beneficial, as they don't compete for the same nutrients and can help loosen the soil. Dill attracts beneficial insects that prey on aphids and other pests. 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 pests as mustard greens, and tomatoes can stunt the growth of mustard greens.