Green Onions in Zone 6A — Southeast

Green onions are a must-grow in the Southeast. They bring a mild, fresh onion flavor to all kinds of dishes, and they're incredibly versatile. Imagine snipping fresh green onions right from your garden to top off your summer corn on the cob or add to a cool cucumber salad on a hot, humid day. Plus, the satisfaction of growing something you use almost daily is hard to beat.

Our long growing season here in the Southeast means you can have green onions almost year-round. We do have to contend with humidity and the occasional pest, but with a little planning, you can easily overcome these challenges. With a 198-day growing season, you'll have plenty of time to get multiple harvests.

If you want to get a jump start, you can transplant green onions outdoors from mid-March through early April. This gives them a head start before the real heat kicks in.

Before transplanting, be sure to harden off your seedlings. Gradually expose them to the outdoors for about a week, increasing their time outside each day. Space them about 2-3 inches apart in well-drained soil.

Keep an eye on the weather during this time. We can still get some late frosts here in the Southeast, so be ready to cover your transplants if needed.

Direct sowing is the easiest way to grow green onions, and you can do it from mid-March through mid-August. This gives you a long window to get successive plantings going.

Simply prepare your soil by loosening it and adding some compost. Green onions aren’t too picky, but they do like well-drained soil. Sow seeds about ¼ inch deep and 2-3 inches apart. Keep the soil consistently moist until they germinate. You can also plant the root ends of store-bought green onions, just pop them in the soil and they'll regrow.

Green onions need consistent moisture to stay happy, but they don't like soggy feet. Since our summers here in the Southeast are hot and humid, finding the right balance is key.

During the spring and fall, when temperatures are milder, aim to give your green onions 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 that to 1.5 inches per week. Stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water.

Water at the base of the plants to avoid getting the leaves wet. Overhead watering 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 light layer of mulch, like pine straw, can help retain moisture and suppress weeds.

You can expect your first harvest of green onions starting in mid-May and continuing through early November. That’s a long harvest window!

Green onions are typically ready to harvest about 60-70 days after planting, when the stalks are about pencil-thick. You can either pull up the entire plant or cut the stalks off about an inch above the soil line. If you cut them, they'll usually regrow, giving you multiple harvests from the same plant.

To encourage continued production, make sure to keep the soil moist and fertilize lightly every few weeks. As our first frost approaches in late October, you can either harvest all your remaining green onions or cover them with a cold frame to extend the season a bit longer.

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

Onion Maggots

• What it looks like: Wilting or yellowing plants, stunted growth, and small white maggots feeding on the roots.
• What causes it: These pests are attracted to onions and lay their eggs near the base of the plants.
• How to fix/prevent it: Use row covers to prevent the adult flies from laying eggs. Introduce beneficial nematodes to the soil.

Thrips

• What it looks like: Silvery or white streaks on the leaves, distorted growth, and tiny, slender insects on the plants.
• What causes it: These small pests suck the sap from the leaves, causing damage. They thrive in hot, dry conditions.
• How to fix/prevent it: Encourage beneficial insects like ladybugs and lacewings. Use insecticidal soap or neem oil.

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. Different species affect different plants.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation. Water at the base, never overhead. Copper-based fungicides for prevention. Plant resistant varieties where available.

Pink Root

• What it looks like: Pink or reddish roots, stunted growth, and yellowing leaves.
• What causes it: This fungal disease thrives in warm, wet soils.
• How to fix/prevent it: Improve soil drainage. Rotate crops to avoid planting onions in the same spot year after year. Solarize the soil in summer to kill the fungus.

Southeast Specific Challenges: Our hot, humid summers and frequent afternoon thunderstorms create the perfect conditions for fungal diseases like downy mildew and pink root. Make sure to provide good air circulation, water at the base of the plants, and consider using preventative fungicides. Japanese beetles can also be a nuisance, so keep an eye out for them and handpick them off the plants as needed.

Companion planting can really help your green onions thrive here in the Southeast.

Good companions include carrots, lettuce, tomatoes, peppers, and beets. Carrots help repel onion flies, while green onions deter pests that bother carrots. Lettuce provides ground cover, keeping the soil cool and moist. Tomatoes and peppers benefit from the pest-repelling properties of green onions, and beets help loosen the soil, making it easier for green onions to grow.

Avoid planting green onions near beans and peas. These plants can inhibit each other's growth, and beans and peas don't like the sulfur compounds that onions release into the soil.