Green Onions in Zone 7B — Southeast

Green onions are a must-grow in the Southeast. Their mild, fresh flavor elevates everything from summer salads to grilled dishes. Plus, you can't beat the satisfaction of snipping fresh greens right outside your door, even when it's hot and humid outside.

Our long growing season gives you plenty of time to get multiple harvests, but we also have to deal with humidity and pests. Don't worry, though – with a little planning, you can enjoy fresh green onions from late spring all the way through fall. Our 235-day season gives you lots of chances to get it right!

You can transplant green onion seedlings outdoors in the Southeast from mid February through mid March. This gets them established before the full force of our summer heat arrives. Before planting, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week.

Space transplants 2-3 inches apart in well-drained soil. Keep an eye on the weather forecast, as late frosts can still happen in early spring. If a freeze threatens, cover your young plants with a frost blanket.

Direct sowing is the easiest way to grow green onions here in the Southeast, and you can do it from mid February through late August. Choose a spot with full sun to partial shade. Green onions aren’t too picky, but they’ll appreciate soil amended with compost to improve drainage and fertility.

Sow seeds about ¼ inch deep and 2-3 inches apart. Keep the soil consistently moist until germination, which usually takes about a week. A great trick is to also plant the root ends of store-bought green onions – just stick them in the ground, and they'll regrow!

Green onions need consistent moisture to produce tender, mild stalks, but our Southeast humidity means we have to be careful not to overwater. During the spring and fall, when temperatures are milder and we get those nice, soaking afternoon thunderstorms, aim for about 1 inch of water per week, either from rainfall or irrigation.

In the heat of summer, especially during dry spells, you might need to increase watering to 1-1.5 inches per week. The finger test is your friend: stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. Always water at the base of the plants to avoid wetting the foliage, as this can encourage fungal diseases in our humid climate.

Signs of underwatering include yellowing leaves and stunted growth, while overwatering can lead to root rot. A layer of mulch, like pine straw or shredded leaves, can help retain moisture and suppress weeds, which is a big plus in our long summer.

You can expect your first harvest of green onions in late April through mid November here in Zone 7B. Green onions are usually ready to harvest about 60 days after planting, when the stalks are about pencil-thick. Don't wait too long, or they can become tough and strongly flavored.

To harvest, you can either pull up the entire plant or, for continuous production, cut the stalks about an inch above the base. The plant will regrow, giving you multiple harvests. As our first frost approaches in early November, harvest any remaining green onions to use fresh or preserve for later.

Here are some common problems you might encounter growing green onions in the Southeast:

Onion Maggots

• What it looks like: Wilting or yellowing leaves, stunted growth, and small white maggots feeding on the roots and bulb.
• What causes it: Flies lay eggs at the base of the plants, and the hatched maggots burrow into the roots.
• How to fix/prevent it: Use row covers to prevent flies from laying eggs. Introduce beneficial nematodes to the soil. Remove and destroy any infested plants.

Thrips

• What it looks like: Silvery or white streaks on the leaves, distorted growth, and tiny, slender insects visible on the plant.
• What causes it: These tiny pests suck plant juices, causing damage and weakening the plant.
• How to fix/prevent it: Encourage beneficial insects like ladybugs and lacewings. Use insecticidal soap or neem oil. Keep the area around your plants free of weeds.

Downy Mildew

• What it looks like: Yellow patches on leaf tops with fuzzy gray-purple growth on undersides. Leaves brown and die from the bottom up.
• What causes it: Oomycete pathogen that spreads in cool, humid conditions via wind-carried spores.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation. Water at the base, never overhead. Copper-based fungicides for prevention.

Pink Root

• What it looks like: Pink or reddish roots, stunted growth, and yellowing leaves.
• What causes it: A soilborne fungus that infects the roots, hindering water and nutrient uptake.
• How to fix/prevent it: Improve soil drainage. Rotate crops to avoid planting onions in the same spot year after year. Solarize the soil during the hot summer months to kill off the fungus.

Southeast Specific Challenges: Our hot, humid summers and wet-summer rainfall create ideal conditions for fungal diseases like downy mildew. Good air circulation, proper watering techniques, and proactive use of fungicides can help mitigate these issues. Also, keep an eye out for Japanese beetles, which can sometimes munch on the leaves.

Companion planting can help your green onions thrive in the Southeast. Carrots are great companions because they deter onion flies. Lettuce benefits from the pest-repelling properties of green onions. Tomatoes and peppers also do well planted near green onions, as the onions can help deter certain pests. Beets are also a good choice, as they don't compete for the same nutrients.

Avoid planting beans and peas near green onions, as they can inhibit each other's growth. The alliums in green onions can stunt the growth of legumes.