Green Onions in Zone 6B — Midwest

Green onions are a must-grow in any Midwest garden. Their fresh, mild flavor elevates everything from summer salads to grilled dishes, and they’re so easy to snip right when you need them. There's nothing quite like the satisfaction of pulling a few green onions from your own fertile soil to add a little zing to your dinner, especially after a long winter.

Our Midwest weather can be unpredictable, with those variable spring temperatures and occasional summer heat spells. But don't worry—green onions are surprisingly resilient, and with our 183-day growing season, you'll have plenty of time to enjoy a continuous harvest. Just keep an eye out for late frost.

You can transplant green onions outdoors in the Midwest from mid March through mid April. Before you put them in the ground, make sure you harden them off. Give them about a week of gradually increasing outdoor exposure to get them used to the elements.

Space your transplants about 2-3 inches apart. Keep in mind that the Midwest spring weather can be a bit touch-and-go at this time, so be prepared to cover them if a late frost is in the forecast.

Direct sowing is the easiest way to grow green onions here in the Midwest. You can start sowing seeds from mid March through early August, giving you a long window for multiple harvests. Green onions are very productive, so staggering plantings is a good idea.

Choose a spot with full sun to partial shade and make sure the soil is loose and well-drained. Although our soil is fertile, adding some compost never hurts. Sow seeds about ½ inch deep, spacing them 2-3 inches apart. Keep the soil consistently moist, especially until they germinate. For a super easy start, you can even plant the root ends of store-bought green onions – they'll regrow!

Green onions need consistent moisture to thrive, especially here in the Midwest where we can swing from wet springs to moderate-to-hot summer heat spells pretty quickly. They aren't drought tolerant, and their shallow roots dry out fast. The goal is tender, mild stalks, and that means keeping the soil consistently moist.

During the spring, when we tend to get plenty of rainfall, you might not need to water much at all. But once those summer heat spells hit, you’ll need to be more diligent. Stick your finger about 2 inches deep into the soil – if it feels dry, it's time to water. Aim for about an inch of water per week, either from rain or irrigation.

Water at the base of the plants to avoid getting the leaves wet, especially with our moderate-to-humid conditions. Overhead watering can encourage fungal diseases. If you notice the leaves are turning yellow or wilting, you might be underwatering. If the leaves are yellowing and the base of the plant feels mushy, you're likely overwatering. A light layer of mulch can help retain moisture and keep the soil cool during those hot summer months.

You can expect your first harvest of green onions in the Midwest starting around mid May and continuing all the way through late October. They're usually ready about 60-70 days after planting. Look for stalks that are about pencil-thick.

You have a couple of options for harvesting. You can pull the entire plant from the ground, or you can cut the green onion about an inch above the soil line. If you cut them, they'll regrow, giving you multiple harvests from the same plant. Keep harvesting regularly to encourage continued production.

As our first frost approaches in mid- October, harvest any remaining green onions. You can chop and freeze them for use throughout the winter, or try overwintering some in a cold frame for an early spring harvest.

Green onions are generally easy to grow, but here in the Midwest, you might run into a few common problems:

• 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 the smell of onions and lay their eggs near the base of the plants. The maggots then burrow into the roots.
• How to fix/prevent it: Use row covers to prevent the adult flies from laying eggs. Rotate your crops each year. Introduce beneficial nematodes to the soil.
• Thrips
• What it looks like: Silvery streaks or white patches on the leaves, distorted growth, and tiny black insects visible on the plant.
• What causes it: Thrips are tiny insects that suck the sap from plants, causing damage to the leaves and stems.
• How to fix/prevent it: Spray plants with insecticidal soap or neem oil. Encourage beneficial insects like ladybugs and lacewings.
• 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: Roots turn pink or reddish, stunted growth, and yellowing leaves.
• What causes it: A soilborne fungus that thrives in warm, wet conditions.
• How to fix/prevent it: Improve soil drainage, rotate crops, and use disease-free transplants. Solarize the soil in the summer to kill the fungus.

Midwest Specific Challenges: Our moderate-to-hot heat, moderate-to-humid humidity, and wet-summer rainfall can create ideal conditions for fungal diseases like downy mildew and root rot. Good air circulation and proper watering practices are key to preventing these problems.

Companion planting can give your green onions a boost in the Midwest garden. Carrots are great companions because their scent deters onion flies. Lettuce thrives in the partial shade provided by green onions, and they don't compete for the same nutrients. Tomatoes and peppers also benefit from being planted near green onions, as the onions can help repel certain pests. Beets are also good companions, as they improve the soil structure.

Avoid planting green onions near beans and peas. These plants inhibit each other's growth, reducing your overall harvest.