Green Onions in Zone 4A — Northeast

Green onions are a must-grow for any Northeast garden. Their mild, fresh flavor elevates everything from summer salads to grilled dishes, and there's nothing quite like snipping them fresh from your garden. Plus, they're incredibly versatile: use the green tops, the white bulbs, or both!

Our short growing season in the Northeast, combined with potential late spring frosts and early fall frosts, can seem daunting. But with a little planning, you can easily enjoy a continuous harvest of green onions throughout our brief-but-productive summers. With a 128-day growing season, you'll have plenty of time.

You can transplant green onion seedlings outdoors in the Northeast from mid April through mid May. Be sure to harden them off for about a week before planting. Give them gradually increased exposure to the sun and wind.

Space your transplants about 2-3 inches apart in rows. Our weather can be unpredictable at this time of year, so keep an eye on the forecast. Be ready to cover them if a late frost threatens.

Direct sowing is the easiest way to grow green onions here. Start sowing mid April and continue through early July for a continuous harvest. Green onions aren't fussy, but they prefer well-drained soil. Amend our rocky New England soil with compost for best results.

Sow seeds about ¼ inch deep and 2-3 inches apart. Keep the soil consistently moist until they germinate. 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 produce those tender, mild stalks we love. The key is to keep the soil consistently moist, but not soggy. Their shallow roots can dry out quickly, especially during our warmer summer days.

In the Northeast, aim to water your green onions deeply about once or twice a week, providing about 1 inch of water each time. Stick your finger about 2 inches deep into the soil – if it feels dry, it's time to water. Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases in our moderate-to-humid climate.

Yellowing leaves can be a sign of both overwatering and underwatering. If the leaves are yellowing and the soil is soggy, you're likely overwatering. If the leaves are yellowing and the soil is dry to the touch, you need to water more. A light layer of mulch, like straw, can help retain moisture and keep the soil cool during the summer.

You can expect your first harvest of green onions from mid June through late September, depending on when you sowed them. They're usually ready about 60 days after planting. Look for stalks that are at least pencil-thick.

To harvest, you can either pull up the entire plant or cut the green tops off about an inch above the soil. If you cut them, they'll often regrow, giving you multiple harvests. As our first frost approaches in mid- September, harvest any remaining green onions. You can chop and freeze them for use throughout the winter.

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

Onion Maggots

• What it looks like: Yellowing, wilting plants. The bulbs may be tunneled and rotting.
• What causes it: Small, white larvae that feed on the roots and bulbs. They are more prevalent during cool, wet springs.
• How to fix/prevent it: Use row covers to prevent the adult flies from laying eggs. Remove and destroy any infested plants.

Thrips

• What it looks like: Silvery streaks or white blotches on the leaves. The leaves may also be distorted or stunted.
• What causes it: Tiny, slender insects that suck the sap from the leaves. They thrive in hot, dry weather.
• How to fix/prevent it: Encourage beneficial insects like ladybugs and lacewings. Spray plants with a strong stream of water or insecticidal soap.

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.

Pink Root

• What it looks like: Roots turn pink or reddish, and the plants may be stunted or wilted.
• What causes it: A soilborne fungus that infects the roots. It is more common in warm, wet soils.
• How to fix/prevent it: Improve soil drainage. Rotate crops to avoid planting onions in the same spot year after year.

Northeast Specific Challenges: Our moderate heat, moderate-to-humid humidity, and even rainfall can create ideal conditions for fungal diseases like downy mildew. Good air circulation and careful watering practices are key to preventing these problems.

Good companions for green onions in the Northeast include carrots, lettuce, tomatoes, peppers, and beets. Carrots and onions are mutually beneficial, as the onion scent deters carrot root flies, and the carrot scent deters onion flies. Lettuce benefits from the pest-repelling properties of onions. Tomatoes and peppers also benefit from onion's pest-repelling qualities. Beets improve the soil structure, which helps onions thrive.

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