Green Onions in Zone 3A — Great Plains

Green onions are a must-have for any Plains garden. They're easy to grow, add a fresh bite to everything from grilled meats to salads, and are incredibly satisfying to snip right from your backyard. Plus, their quick growth means you can sneak in a harvest even with our shorter growing season.

Our Great Plains weather can be a bit wild, with those extreme temperature swings and occasional hail. But green onions are pretty forgiving. With the right timing, you can easily squeeze in a couple of harvests during our roughly 108-day growing season.

If you're starting green onions indoors, get them in the ground sometime from late April through late May. This gives them plenty of time to establish before the heat of summer hits.

Before transplanting, harden them off for about a week. Give them increasing amounts of time outdoors, so they can adjust to the wind and sun.

Space transplants about 2-3 inches apart. Keep an eye on the forecast for any late frosts or sudden cold snaps – row covers are your friend during this time of year.

Direct sowing is the way to go with green onions. It's simple and they sprout easily. Sow seeds from late April through late June for a continuous harvest.

Make sure your soil is loose and well-draining. Green onions aren't too picky, but they prefer a soil temperature around 50-75°F for best germination. Sow seeds about ½ inch deep, spacing them 2-3 inches apart. For a super easy start, you can even plant the root ends of store-bought green onions directly in the ground.

Green onions need consistent moisture to stay happy. Our Plains summers can be hot and dry, so regular watering is important, but be careful not to overdo it.

During the peak of summer, especially when temperatures hit those typical highs around 93°F, check the soil moisture every few days. Stick your finger about 2 inches deep – if it feels dry, it's time to water. Aim for about 1 inch of water per week, either from rainfall or irrigation. Water at the base of the plants to avoid wetting the foliage, especially with our low-to-moderate humidity.

If the leaves start to yellow and droop, you're likely overwatering. If they wilt and turn brown at the tips, they're probably thirsty. A light layer of mulch, like straw or grass clippings, can help retain moisture and regulate soil temperature, which is crucial with our variable rainfall.

Your first harvest of green onions should be ready from late June through mid September, about 60 days after planting. They're generally ready when the stalks are about pencil-thick.

You can either pull up the entire plant or cut the stalks about an inch above the soil line. If you cut them, they'll often regrow for another harvest or two.

As we approach early September and the first frost, harvest any remaining green onions. You can chop and freeze them for use throughout the winter, bringing a little bit of summer into those cold Plains days.

Here are some common problems you might face with green onions in the Great Plains:

Onion Maggots

• What it looks like: Wilting or yellowing plants, often with stunted growth. You might find small, white maggots near the base of the bulb or roots.
• What causes it: These pests thrive in moist soil and attack the roots. Our variable spring weather, with periods of wetness, can encourage them.
• How to fix/prevent it: Use row covers to prevent the adult flies from laying eggs. Remove and destroy any infested plants. Rotate your crops each year.

Thrips

• What it looks like: Silvery or white streaks on the leaves, often with tiny black specks (their droppings). Leaves may become distorted or curled.
• What causes it: Thrips are tiny insects that suck plant juices. They love hot, dry conditions, which we often get in the Plains during summer.
• How to fix/prevent it: Encourage beneficial insects like ladybugs and lacewings. Use insecticidal soap or neem oil, applying it in the evening.

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. Plant resistant varieties where available.

Pink Root

• What it looks like: Roots turn pink or reddish, and the plant may be stunted or wilted.
• What causes it: A soilborne fungus that thrives in warm, moist conditions.
• How to fix/prevent it: Improve soil drainage. Rotate your crops. Solarize the soil during the hottest part of summer to kill the fungus.

Great Plains Specific Challenges: Our hot summers can stress green onions, making them more susceptible to pests and diseases. Wind protection is essential to prevent damage. Variable rainfall means you need to be vigilant about watering, but also prepared for potential downy mildew outbreaks during wetter periods.

Companion planting can help your green onions thrive in the Plains. Carrots are great companions because they deter onion flies, while green onions repel carrot root flies. Lettuce benefits from the shade provided by green onions, which is especially helpful during our hot summers. Tomatoes and peppers also benefit from green onions, as they can deter certain pests. Beets are also good companions, as they don't compete for the same nutrients. Avoid planting beans and peas near green onions, as they can inhibit each other's growth.