Green Onions in Zone 6A — Pacific Northwest

Green onions are a fantastic addition to any Pacific Northwest garden. They offer a fresh, mild onion flavor that elevates everything from stir-fries to salads, and their versatility makes them a kitchen staple. Plus, in our climate with its cool nights, you'll find the flavor is often sweeter and less pungent than what you'd get from the store.

While we might struggle with heat-loving plants, green onions thrive in our mild summers. Our 148-day growing season gives you ample time to get several harvests from a single planting. With a little attention to timing, you can easily enjoy fresh green onions from mid-June all the way into the fall.

If you're starting your green onions indoors, aim to transplant them outdoors from mid-April through early May. This gives the soil a chance to warm up a bit after our wet springs. Before transplanting, be sure to harden off your seedlings. Give them about a week of gradual exposure to the outdoors, increasing the time each day.

When transplanting, space the seedlings about 2-3 inches apart in rows. This gives them enough room to develop without overcrowding. Keep an eye on the weather forecast, as we can still get some unexpected cool snaps and even a late frost during this period.

Direct sowing is the easiest way to grow green onions here in the PNW. You can start sowing seeds from mid-April through late July. This extended planting window lets you stagger your harvests for a continuous supply.

Choose a spot with full sun to partial shade and prepare the soil by loosening it and adding some compost. Green onions aren't too picky, but they do appreciate well-draining soil. Sow seeds about ¼ inch deep and 2-3 inches apart. Keep the soil consistently moist until the seedlings emerge. As a bonus, you can also plant the root ends of store-bought green onions. Just stick them in the ground and watch them regrow!

Green onions need consistent moisture to thrive, but they don't like to be waterlogged. In our PNW climate, with its dry summer months, you'll need to pay attention to watering, especially during the drier periods. While we rarely see temperatures above 90°F, the dry air can still quickly dry out the soil.

During the spring and early summer, when rainfall is more frequent, you might only need to supplement with watering once or twice a week, giving them about 1 inch of water each time. Use the finger test to check soil moisture: stick your finger about 2 inches deep into the soil. If it feels dry, it's time to water. As the dry summer months set in, increase watering to 2-3 times a week, especially if you're growing them in containers. Water at the base of the plants to avoid wetting the foliage, which can encourage fungal diseases.

Signs of underwatering include wilting or yellowing leaves. Overwatering can lead to root rot, indicated by mushy or slimy stalks. A layer of mulch around your green onions will help retain moisture and suppress weeds, which is always a win.

You can expect your first harvest of green onions starting in mid-June, about 60 days after planting. Look for stalks that are at least pencil-thick. They'll be ready to harvest anytime from then through mid-October.

To harvest, you can either pull the entire plant from the ground or cut the green onion about an inch above the soil line. If you cut them, they'll often regrow, giving you multiple harvests from a single planting. To encourage continued production, be sure to water and fertilize lightly after harvesting. As the first frost approaches in early October, harvest any remaining green onions to use fresh or freeze for later.

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

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 smell of onions and lay their eggs near the base of the plants.
• How to fix/prevent it: Use row covers to prevent the adult flies from laying eggs. You can also introduce beneficial nematodes to the soil to control the maggots.

Thrips

• What it looks like: Small, silvery streaks on the leaves, distorted growth, and tiny black specks (thrip droppings).
• What causes it: Thrips are tiny insects that suck the sap from plants, causing damage.
• How to fix/prevent it: Encourage beneficial insects like ladybugs and lacewings, which prey on thrips. You can also use insecticidal soap or neem oil to control infestations.

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.
• How to fix/prevent it: Remove affected leaves immediately. Improve air circulation. Water at the base, never overhead. Copper-based fungicides can be used for prevention.

Pink Root

• What it looks like: The roots turn pink or reddish, and the plants may be stunted and wilted.
• What causes it: A soilborne fungus that thrives in warm, moist conditions.
• How to fix/prevent it: Improve soil drainage and avoid overwatering. Rotate crops to prevent the fungus from building up in the soil.

Pacific Northwest Specific Challenges: Our mild heat and dry-summer rainfall can actually be beneficial for green onions, as they don't like extreme heat or overly wet conditions. However, late blight can be a concern, especially if you're growing tomatoes or potatoes nearby. Good air circulation and proper watering practices can help prevent this. Slugs can also be a nuisance, so use your preferred method of slug control to protect your plants.

Green onions are great companions for many plants in the PNW garden. Carrots benefit from the onion's pungent smell, which deters carrot root flies. Lettuce also enjoys the shade provided by green onions, which can help prevent bolting in our mild summers. Tomatoes and peppers benefit from the pest-repelling properties of green onions. Beets also grow well alongside green onions, as they don't compete for the same nutrients. Avoid planting green onions near beans and peas, as they can inhibit the growth of these legumes.