Learning how to grow onions from seeds and how to plant onions not only gives you more variety but also gives you more self-sufficiency.
Our family loves cooking with onions, so a few years ago, we decided to learn how to grow onions of our own. We began with onion starts we purchased over the internet and had good success, but after reading about starting our own seeds, we had to try it. From there, we’ve progressed to growing more varieties, larger onions, and more significant amounts. This year, we grew about 1,000 onions that we started ourselves!
First, if you’re a beginner learning how to grow onions take heart; onions are not an overly difficult crop to grow. They require lots of nitrogen, rich soil, consistent water, and sunshine. Our area has few onion pests, and what we have does minimal damage. However, each area is unique, so check with other onion growers in your area for pest specifics.
Where can you grow onions?
Onions can be grown in high tunnels, in the garden, in raised beds, and even in containers. Build hills to plant the onions in for planting directly into the ground. If you’re planting in raised beds, this isn’t necessary. If your soil is hard, add compost to loosen it. Mulch will help retain moisture and prevent weeds. You may either add mulch such as straw, pine needles, or chopped leaves or place strips of cardboard in the middle of the rows (don’t place cardboard too closely to the onions, or they may not bulb effectively).
Variety matters when learning how to grow onions.
When learning how to grow onions, varieties matters. Many varieties of onions are broken down into three categories: short-day, intermediate, and long-day. Look at a map for onions, as this will show your general area. Long-day onions are generally grown in the northern half of the U.S., intermediate in roughly the middle strip, and short-day in southern states. If you live in another country, check your onion zone! According to bonnieplants.com, long-day onions require 14 to 15 hours of sunlight, short days require 10, and intermediate are in the middle. Some onions are best suited for certain climates, such as “cool, mountainous,” so don’t grow these if you live in a hot, humid climate like we do and expect good results. We’re in zone 6 and considered intermediate, so we are able to grow some of both kinds.
Growing onions from seeds or starts.
You can buy starts (not onion sets that produce green onions but won’t grow bulbing onions) or start growing your onions from seeds. As with anything, the seeds provide a much greater variety of choices than buying starts does. However, you will need seed starting trays (reused bowls, small totes, and plastic cups also work great ), a light and extra time for seeds. In our zone, we need to start onions on the first of January. If you live in a southern zone, you may often start seeds in the summer, plant in the fall, and harvest in spring. We tried this and got a minimal harvest. After research, we realized that to do this successfully, we would need to plant short-day varieties, not intermediate like we had.
How to grow onions from seeds.
To start onion seeds, place moistened seed-starting soil into containers with drain holes. Gently pack. Sow seeds in rows or just broadcast them in the containers. Unlike many crops, you can seed onions close together. Cover with seed-starting soil and lightly spray with water to moisten (not soak) the top. Now, you may place the containers into plastic bags, put a lid on them, or keep the soil sprayed daily until the seeds sprout. In our experience, these sprout much quicker in a warm room. We start ours on a stand near our wood stove. After the seeds sprout, remove any lids or coverings and place about 2 inches below full-spectrum growing lights. There are two schools of thought on pruning your onion tops. One says to do it when they reach 4 inches and continue to prune until you set them into the garden. The other says never to prune them, and you’ll get bigger bulbs. We have done both and quite honestly achieved good results with both. One advantage of pruning is that you won’t need to keep moving your lights up as they grow, and you can also eat the prunings! Make sure your onions don’t dry out, but also don’t waterlog them. Fertilize with a weak natural fertilizer weekly (we use fish/seaweed emulsion at 1/4 strength).
When and how to plant onions outside.
Onions need to be planted as early as possible. In my area, this is March (if we had a high tunnel, we could plant in February) for a harvest in late June. The longer the onions have to grow before it gets too hot, the better they’ll be! Onions are incredibly hardy and can withstand frost and even some freezes. Gently separate the roots in your containers and plant your onions where all the tops are out of the ground and the roots barely in; don’t bury them deeper! Plant 6 inches apart in rows and place the rows 6 to 9 inches apart. Water in well. Onions require lots of nitrogen for proper growth, so make sure your soil is nitrogen-rich. Either fertilize with a pelletized natural fertilizer with a high nitrogen content or side dress with aged chicken, rabbit, or goat manure.
Water and Fertilizer for onions.
Learning how to grow onions means learning about onion fertilizer. As your onions grow, fertilize every two weeks. We dig furrows beside each row and bury the fertilizer. We also spray ours with a mixture called “Chicken Soup for the Soil” and a fish/seaweed emulsion. Keep the onions watered. They may require daily watering during dry weather. Weeding is essential for onions as they intensely dislike competing with weeds. Loose soils make the biggest onions in our experience, as does full sun.
How to grow onions once they are planted.
Onion tops will eventually make your bulbs, so don’t clip the tops once you plant them in your garden. Keep an eye out for worms or other pests and treat them promptly. We use A few natural pesticides in our garden: diatomaceous earth, neem, bt, and spinosad. Handpicking pests is often effective for minimal problems.
Once your onions start bulbing ( where the bottom or root swells), stop fertilizing but continue to water well. Some people recommend loosening the dirt around the bulbs as they grow, but this isn’t necessary as the bulbs will naturally push back the soil.
When to harvest onions.
You’ll know your onions are about ready for harvest when the tops start falling over. Stop watering at this point. After 50% of the onions have fallen over, you can bend the rest over. Pull the onions when the outer tops have browned. Grasp the onions at the bottom of the stem and firmly tug up. If the stem is too dry, it will most likely break off, so pulling them before they get too browned is best. Brush off any dirt, don’t remove the skin layer on the outside of the onions, and leave the tops on.
How to cure onions.
You’ll need to let your onions sit in a breathable area for several weeks to cure them for long-term storage. There are several different options for this. We take a long board and nail heavy nails part-way into it every 6 inches. Then we take a handful of onions, tie a piece of twine onto them (binding them together), and then hang the bundle on the nail. The size and weight of the onions determine how many are in each bundle. We generally put 8 to 12 onions together. This board is fastened under a protected side of a shed where they get air but no rain. Another method that works well but requires more room is a series of screened frames you can lay the onions out flat on (side by side, not on top of each other). Still others cure theirs in the garden, but only do this if you have dry weather!
How to store onions from the garden.
Once the tops have dried or the stem right above the bulb is dried, cut the tops off about 1 to 2 inches above the bulb, place them in netted bags, and store them in a cool, dry place. Different varieties have different storage times, so keep a close eye on them. We store ours in netted bags under the house hanging from nails on the floor rafters. Any bulbs that are tiny or damaged should be used or preserved promptly. A few options for preserving are chopping and freezing, dehydrating, and pickling.
What onion varieties are best?
There are a multitude of wonderful onion varieties and many suppliers. We bought our seeds from Southern Exposure Seed Exchange and were extremely pleased with the quality. They sprouted well, and we had an excellent crop. The varieties we tried this year were Walla Walla, Red Wethersfield, and Texas Supersweet (a hybrid from another company). Of these three, our favorite was Walla Walla. They were a big, beautiful, sweet yellow onion. The Red Wethersfield grew well but weren’t as large and turned out quite spicy. The Texas Super Sweet, a short-day variety, was our least favorite because they didn’t get as large (but were delicious), and in hindsight, I think we were just too far north for their preferred climate. Remember to read the description of each onion variety before you purchase!
Here are some varieties that I recommend you try when you’re learning how to grow onions:
Short day: Texas Early Grano, Texas Super Sweet, Red Creole; intermediate: Candy, Red Candy Apple, Walla Walla (this is also a long day); long day: Red Wethersfield, Rossa di Milano, Utah Yellow Sweet Spanish.
Growing onions is a great way to become more sustainable on your homestead, and I encourage you to try it and see if those homegrown onions aren’t a tasty, healthy addition to your meals!
