Green Onions in Zone 4A — Midwest

Green onions are a must-grow in any Midwest garden. Their fresh, mild flavor elevates everything from summer salads to grilled brats, and they're so easy to snip and add to dishes right from your backyard. Plus, there's something deeply satisfying about pulling up a bunch of vibrant green onions from our fertile soil, knowing you grew them yourself.

Our Midwest weather can be a bit unpredictable, especially in spring, and we can get some summer heat spells. But don't worry, with a 128-day growing season, you'll have plenty of time to get your green onions established and enjoy a bountiful harvest. Careful timing is key, and we'll walk you through it.

If you're starting your green onions indoors, you can transplant them outside anytime from mid-April through mid-May. Make sure you harden them off first by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the Midwest weather.

Space your transplants about 2-3 inches apart in rows. Keep an eye on the forecast – we can still get a late frost in April or May, so be ready to cover your seedlings if needed.

Direct sowing is the easiest way to grow green onions here in the Midwest. You can sow seeds directly into the garden from mid-April through early July. This gives you a long window to get successive plantings going.

Choose a spot with full sun to partial shade and prepare the soil by loosening it and adding compost. Green onions aren't too picky, but they appreciate fertile soil. Sow seeds about ¼ inch deep and 2-3 inches apart. Keep the soil consistently moist until they germinate. For a continuous supply, sow a new batch of seeds every few weeks. Another trick? Plant the root ends of store-bought green onions—they'll happily regrow!

Green onions need consistent moisture to thrive, especially with our moderate-to-hot summer heat. They aren't drought-tolerant and shallow roots mean they dry out quickly. During the hotter months, you might need to water them more frequently.

A good rule of thumb is to water deeply when the top 2 inches of soil feel dry to the touch – the "finger test." Aim for about 1 inch of water per week, either from rainfall or irrigation. Watering at the base of the plants is best, especially with our moderate-to-humid conditions, to avoid creating a breeding ground for fungal diseases on the leaves.

If the leaves start to yellow and droop, you're likely overwatering. If they become limp and pale green, they need more water. A layer of mulch around your green onions can help retain moisture and keep the soil cool during those summer heat spells, which is a big help.

You can expect your first harvest of green onions starting in mid-June and continuing through late September. Green onions are usually ready to harvest about 60 days after planting, when the stalks are about pencil-thick.

You can either pull up the entire plant or cut the green onion above the base, leaving the roots in the ground to regrow. For continuous production, harvest only what you need, and the remaining plants will keep producing new growth. As the first frost approaches in mid-September, harvest any remaining green onions to enjoy before the cold weather sets in.

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

• 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: These pests thrive in moist soil conditions, which we often have in the Midwest during spring and early summer.
• How to fix/prevent it: Use row covers to prevent adult flies from laying eggs near your plants. Rotate your crops each year. Introduce beneficial nematodes to the soil.
• 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: Thrips are more prevalent during hot, dry periods, but can still be an issue during our Midwest summer heat spells.
• How to fix/prevent it: Encourage beneficial insects like ladybugs and lacewings. Use insecticidal soap or neem oil. Water plants regularly, as stressed plants are more susceptible.
• 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: An oomycete pathogen that spreads in cool, humid conditions via wind-carried spores. Different species affect different plants. Midwest springs are often cool and humid, creating ideal conditions.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation. Water at the base, never overhead. Copper-based fungicides can help prevent spread. Plant resistant varieties where available.
• Pink Root
• What it looks like: Roots turn pink or reddish, and the plant's growth is stunted.
• What causes it: A soilborne fungus that thrives in warm, moist conditions and is more severe in poorly drained soils.
• How to fix/prevent it: Improve soil drainage by adding compost. Rotate crops to avoid building up fungal populations in the soil. Solarize the soil during the hottest part of summer to kill the fungus.

Midwest Specific Challenges: Our moderate-to-hot summer heat and moderate-to-humid humidity can create favorable conditions for both pests and diseases. Good air circulation and proper watering techniques are essential. Also, our clay soil can be a challenge, so amend it with compost to improve drainage and aeration.

Green onions are great companions for many plants in your Midwest garden. Carrots benefit because the onion scent deters carrot root flies. Lettuce thrives in the partial shade provided by green onions. Tomatoes and peppers are said to benefit from the pest-repelling properties of onions. Beets also grow well alongside green onions.

Avoid planting green onions near beans and peas, as they can inhibit the growth of these legumes. Planting the right companions can really make a difference in your garden's overall health and productivity.