Green Onions in Zone 3B — Great Plains

Green onions are a must-grow here in the Plains. Their mild, fresh flavor adds a zing to everything from summer salads to grilled meats, and they're so easy to snip as needed. Plus, that first taste of homegrown green onion after a long winter? Pure satisfaction.

Our extreme weather can be a challenge, but green onions are quick to mature. With a little planning, you can enjoy a continuous harvest throughout our 118-day growing season. Timing is key, and we'll cover that.

You can transplant green onion seedlings outdoors in late April through mid May, once the soil has warmed up a bit. Be sure to harden off your seedlings for about a week beforehand, gradually exposing them to the outdoor elements.

When transplanting, space the seedlings about 2-3 inches apart. Keep an eye on the weather forecast, as we can still get some unexpected temperature swings and even a late frost during this time. Wind protection is also essential for young transplants.

Direct sowing is the easiest way to grow green onions in our region. Sow seeds directly into the garden from late April through early July. The soil should be at least 50°F for best germination.

Prepare the soil by loosening it and adding some compost. Plant seeds about ¼ inch deep and 2-3 inches apart. Keep the soil consistently moist until the seedlings emerge. For a continuous supply, sow a new batch of seeds every few weeks. Also, don't toss the root ends of store-bought green onions! Stick them in the ground and they'll often regrow.

Green onions need consistent moisture to thrive, especially in our hot Plains summers. Aim to keep the soil evenly moist, but not waterlogged, for the most tender stalks. Their shallow roots dry out quickly.

During the peak of summer, plan to water deeply about 1-2 inches per week. Check the soil moisture by using the "finger test": stick your finger about 2 inches 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 disease in our low-to-moderate humidity.

Underwatering will result in stunted growth and a strong, pungent flavor. Overwatering, on the other hand, can lead to root rot. Wilting leaves can be a sign of either problem, so check the soil moisture before you water. A layer of mulch, like straw or grass clippings, can help retain moisture and keep the soil cool during those hot days.

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

To harvest, you can either pull up the entire plant or cut the green stalks off above the base. If you cut them, the green onions will often regrow, giving you multiple harvests. For continued production, keep the plants well-watered and fertilized.

As our first frost approaches in mid- September, harvest any remaining green onions. You can chop and freeze them for later use, or transplant a few into pots and bring them indoors to enjoy fresh green onions throughout the winter.

Here are some common problems to watch out for with green onions in the Great Plains:

Onion Maggots

• What it looks like: Wilting or yellowing leaves, stunted growth, and small white maggots near the base of the plant.
• What causes it: These pests are attracted to onions and lay their eggs near the base of the plant. The maggots then burrow into the bulb and roots.
• How to fix/prevent it: Use row covers to prevent the flies from laying eggs. Introduce beneficial nematodes to the soil. Remove and destroy any infested plants.

Thrips

• What it looks like: Silvery streaks or spots on the leaves, distorted growth, and tiny black insects on the plant.
• What causes it: These tiny pests suck the sap from the leaves, causing damage. They thrive in hot, dry conditions.
• How to fix/prevent it: Blast plants with a strong stream of water. Introduce beneficial insects like ladybugs and lacewings. Use insecticidal soap or neem oil as a last resort.

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 reddish, and the plant growth is stunted.
• What causes it: A soilborne fungus that infects the roots. It's more common in warm, wet conditions.
• How to fix/prevent it: Improve soil drainage. Rotate crops to avoid planting onions in the same spot year after year. Use resistant varieties if available.

Great Plains Specific Challenges: Our hot summers and variable rainfall can stress green onions, making them more susceptible to pests and diseases. Wind protection is crucial to prevent damage to the delicate foliage. Drought can also be a problem, so be sure to water consistently, especially during dry spells.

Companion planting can help your green onions thrive. Carrots are great companions because they deter onion flies. Lettuce benefits from the protection of green onions, which can repel aphids. Tomatoes and peppers also benefit from the pest-repelling properties of green onions. Beets are good companions as they don't compete for the same nutrients.

Avoid planting green onions near beans and peas. These plants can inhibit the growth of onions.