Green Onions in Zone 3B — Midwest

Green onions are a must-grow in the Midwest garden. Their mild, fresh flavor elevates everything from summer salads to grilled meats, and they're incredibly versatile in the kitchen. Plus, there's nothing quite like the satisfaction of snipping fresh green onions right from your backyard.

Our Midwest weather can be unpredictable, with variable springs and summer heat spells, but green onions are surprisingly resilient. With a little attention to timing and watering, you can enjoy a steady supply throughout our 118-day growing season.

You can transplant green onion seedlings outdoors in late April through mid May, once the soil has warmed up a bit. Before planting, be sure to harden off your seedlings by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the sun and wind.

When you're ready to plant, space the seedlings 2-3 inches apart in well-drained soil. Keep an eye on the Midwest weather forecast for late frosts. If a cold snap is predicted, cover your transplants with a frost blanket to protect them.

Direct sowing is the easiest way to grow green onions in the Midwest. You can sow seeds directly into the garden from late April through early July. Green onions aren't fussy, but they do prefer soil that's been loosened and amended with compost.

Sow seeds about ½ inch deep and 2-3 inches apart. Keep the soil consistently moist until the seedlings emerge. You can 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 thrive, especially with our moderate-to-hot Midwest summer heat. They aren't drought tolerant, so you'll need to pay attention to watering, especially during dry spells. Aim to keep the soil consistently moist, but not waterlogged.

A good rule of thumb is to water deeply about once a week, providing around 1 inch of water. Use the finger test: stick your finger about 2 inches into the soil. If it feels dry, it's time to water. During hotter periods, you might need to water more frequently. Water at the base of the plants to avoid wetting the foliage, as our moderate-to-humid conditions can encourage fungal diseases.

Signs of underwatering include yellowing leaves and stunted growth. Overwatering can lead to root rot, indicated by wilting and mushy stalks. A layer of mulch, like straw or shredded leaves, will help retain moisture and keep the soil cool during our summer heat.

You can expect your first harvest of green onions in late June through late September. Green onions are typically ready to harvest about 60 days after planting, when the stalks are pencil-thick. Don't worry too much about exact timing; you can harvest them at any size you prefer.

To harvest, you can either pull up the entire plant or cut the stalks about an inch above the soil line. If you cut them, the plants will regrow, giving you multiple harvests. As our first frost approaches in mid- September, harvest any remaining green onions, as they won't survive the winter. You can chop and freeze them for later use.

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 are attracted to the onion family and can be particularly problematic during our variable spring weather.
• How to fix/prevent it: Use row covers to prevent the adult flies from laying eggs. Companion planting with carrots can also help deter them.

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 thrive in hot, dry conditions, so they can be an issue during our summer heat spells.
• How to fix/prevent it: Encourage beneficial insects like ladybugs and lacewings. A strong blast of water from the hose can also dislodge them.

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. It can be a concern in our wet-summer climate.
• 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: Roots turn pink or reddish, plants are stunted, and leaves yellow.
• What causes it: A soilborne fungus that's more prevalent in warm, moist soils.
• How to fix/prevent it: Improve soil drainage by adding compost or other organic matter. Crop rotation can also help prevent buildup of the fungus in the soil.

Midwest Specific Challenges: Our moderate-to-hot heat and moderate-to-humid humidity can create favorable conditions for both pests and diseases. Be vigilant about monitoring your plants and taking action quickly to prevent problems from escalating.

Green onions make great companions for many plants in the Midwest garden. Carrots benefit from green onions because the onion scent deters carrot root flies. Lettuce also appreciates the shade provided by green onions during our summer heat. Tomatoes and peppers thrive alongside green onions, as they help repel certain pests. Beets are also good companions, as green onions can help improve their growth.

Avoid planting green onions near beans and peas. Green onions can inhibit the growth of these legumes, so it's best to keep them separated.