Green Onions in Zone 5B — Midwest

Green onions are a must-have in any Midwest garden. Their fresh, mild flavor elevates everything from grilled burgers to summer salads. Plus, they're incredibly versatile – use the greens, the bulbs, or both! There's nothing quite like snipping fresh green onions from your own backyard, knowing exactly where your food comes from.

Our Midwest weather can be unpredictable, with temperature swings in spring and occasional summer heat spells. But don't worry, green onions are surprisingly resilient, and with our fertile soil and adequate rainfall, you can easily fit several harvests into our 168-day growing season. Careful timing is key!

You can transplant green onion seedlings outdoors in late March through late April. Remember to harden them off first. Give them about a week of gradual exposure to outdoor conditions before planting.

When transplanting, space the seedlings 2-3 inches apart. Keep an eye on the forecast, as late frosts are always a possibility here in the Midwest. Be prepared to cover your young plants if a cold snap threatens.

Direct sowing is the easiest and most common way to grow green onions here in the Midwest. Sow seeds directly into your garden beds from late March through late July. This gives you a long window for successive plantings.

Before sowing, make sure your soil is loose and well-draining. Green onions like fertile soil, so amend with compost if needed. Sow seeds about ¼ inch deep, spacing them 2-3 inches apart. You can also plant the root ends of store-bought green onions – just stick them in the ground, and they'll often regrow!

Green onions need consistent moisture to thrive, but overwatering can lead to problems, especially with our moderate-to-humid Midwest summers. Aim to keep the soil consistently moist, but not soggy.

During spring and fall, when temperatures are cooler and rainfall is more frequent, you may only need to water once or twice a week. In the heat of summer, especially during those inevitable summer heat spells, you might need to water every other day. Stick your finger about 2 inches deep into the soil – if it feels dry, it's time to water. Generally, an inch of water per week is a good starting point.

Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our humid climate. Yellowing leaves can indicate overwatering, while drooping or stunted growth suggests underwatering. A light layer of mulch, like straw or shredded leaves, can help retain moisture and suppress weeds.

You can expect your first harvest of green onions in late May through mid October, roughly 60 days after planting. The stalks should be about pencil-thick.

You can either pull up the entire plant or, for continued production, cut the green onion stalks about an inch above the soil line. They'll usually regrow, giving you multiple harvests from a single planting. Keep harvesting regularly to encourage new growth.

As our first frost approaches in early October, harvest any remaining green onions. You can chop and freeze them for use throughout the winter.

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

• Onion Maggots
• What it looks like: Yellowing, wilting plants. Tiny white maggots feeding on the roots and bulbs.
• What causes it: A fly lays its eggs near the base of the plants. The larvae hatch and burrow into the soil.
• How to fix/prevent it: Use row covers to prevent the flies from laying eggs. Introduce beneficial nematodes to the soil.
• Thrips
• What it looks like: Silvery streaks or spots on the leaves. Distorted or stunted growth.
• What causes it: Tiny, slender insects that suck the sap from the leaves.
• How to fix/prevent it: Insecticidal soap or neem oil can help control thrips. 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.
• 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 red. Stunted growth. Yellowing leaves.
• What causes it: A soilborne fungus that thrives in warm, wet conditions.
• How to fix/prevent it: Improve soil drainage. Rotate crops. Plant resistant varieties.

Midwest Specific Challenges: Our moderate-to-hot summers and moderate-to-humid conditions can create a favorable environment for fungal diseases like downy mildew. Be sure to provide good air circulation and avoid overhead watering. Our wet-summer rainfall can also contribute to soilborne diseases like pink root, so ensure your soil is well-draining.

Companion planting can help your green onions thrive! Carrots are great companions because they deter onion flies, and the onions, in turn, deter carrot root flies. Lettuce also makes a good companion, as it provides ground cover and helps to keep the soil cool and moist. Tomatoes and peppers benefit from green onions because the onions deter pests like aphids and spider mites. Beets are also good companions, as they don't compete for the same nutrients in the soil.

Avoid planting green onions near beans or peas. Onions can inhibit the growth of beans and peas.