Green Onions in Zone 7A — Northeast

Green onions are a must-grow in any Northeast garden. Their mild, fresh flavor elevates everything from salads to stir-fries, and you can't beat the satisfaction of snipping them fresh from your garden, especially when cool nights enhance their sweetness. Plus, they're incredibly versatile and productive, making the most of our short growing season.

Sure, we Northeast gardeners face challenges like late spring frosts and early fall freezes. But with a little planning and the right timing, you can easily enjoy a continuous harvest of green onions throughout our 198-day growing season.

If you're starting green onions from sets or transplants, aim to get them in the ground mid-March through early April. Before planting, be sure to harden them off by gradually exposing them to outdoor conditions for about a week. This helps them adjust to the temperature swings we often see this time of year.

When transplanting, space them about 2-3 inches apart. Keep an eye on the weather forecast; a late frost can still happen, so be ready to cover them with a frost blanket if needed.

Direct sowing green onions is the easiest way to go, and you can start mid-March and continue sowing until mid-August for a continuous supply. Choose a spot with full sun to partial shade and well-drained soil – even our rocky New England soil will do if you amend it with some compost.

Loosen the soil and sow seeds about ¼ inch deep, spacing them 2-3 inches apart. Keep the soil consistently moist until germination, which usually takes about a week or two. For an even easier start, you can even 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 in our Northeast climate. While we get decent rainfall, those shallow roots can dry out quickly, especially during the warmer months.

Aim to keep the soil consistently moist, but not soggy. Give them about 1 inch of water per week, either from rainfall or irrigation. The "finger test" is a good way to check: stick your finger about 2 inches into the soil; if it feels dry, it's time to water. It's best to water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our moderate-to-humid climate.

During the spring and fall, when temperatures are cooler and rainfall is more frequent, you might not need to water as often. Signs of underwatering include wilting or yellowing leaves, while overwatering can lead to root rot and yellowing leaves. A layer of mulch will help retain moisture and keep the soil cool.

You can expect your first harvest of green onions mid-May through early November, about 60 days after planting. They're ready to harvest when the stalks are about pencil-thick.

You can either pull up the entire plant or cut the stalks off above the base, leaving the roots in the ground to regrow. For continuous production, harvest selectively, taking only what you need and allowing the rest to keep growing.

As our first frost approaches in late October, harvest any remaining green onions to use fresh or preserve for later. They can also be chopped and frozen for use in cooking.

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

Onion Maggots

• What it looks like: Wilting or yellowing plants, stunted growth, and small white maggots feeding on the roots and bulb.
• What causes it: Onion maggots are the larvae of a fly that lays its eggs near the base of onion plants. They thrive in moist soil.
• How to fix/prevent it: Use row covers to prevent the flies from laying eggs. Remove and destroy any infested plants. Rotate crops each year.

Thrips

• What it looks like: Tiny, slender insects that feed on the leaves, causing silvery streaks and distorted growth.
• What causes it: Thrips are attracted to dry conditions and can be spread by wind.
• How to fix/prevent it: Provide adequate water and use 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.
• 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, stunting growth and causing the plants to wilt.
• What causes it: A soilborne fungus that thrives in warm, moist conditions.
• How to fix/prevent it: Improve soil drainage, rotate crops, and avoid overwatering. Solarize the soil in the summer to kill the fungus.

Northeast Specific Challenges: Our moderate heat, moderate-to-humid humidity, and even rainfall can create favorable conditions for fungal diseases like downy mildew and root rot. Careful monitoring, proper watering practices, and good air circulation are essential for keeping your green onions healthy.

Companion planting can help your green onions thrive. Carrots are great companions because their scent deters onion flies, while green onions deter carrot root flies. Lettuce benefits from the shade provided by green onions, and tomatoes and peppers also do well planted near green onions, as they can help repel certain pests. Beets are also great companions.

Avoid planting green onions near beans and peas, as they can inhibit each other's growth.