Planting onions using seedlings is the only way to go in my humble opinion. Let’s talk about why!
3 Onion Planting Options and why to choose seedlings
There are 3 different ways to plant onions; seeds, sets and seedlings.
1. Planting onions by seeds
It takes a long time to grow an onion from seed. Only those of you in the mildest of climates will really see good success by planting seeds directly into the garden. I want my onions to be ready in early August each year. In order for me to have them ready from seed I would need to plant them in the garden in early February. No way that is happening in my Zone 5/6 garden! This will be the case for most of you. For the bulk of us in the northern hemisphere planting onions by seed outdoors is just not an option.
2. Planting onions by Sets.
Onion sets are partially grown onions. They are usually no larger than an inch or so. These sets are planted just below the surface in the early spring and they sprout and produce a mature onion bulb. Many folks plant onions this way and have great success. This is the way I planted onions for the first 10 years we gardened and we always had a decent crop.
The problem with onion sets is that the sets are actually in their second year. Onions are biennial plants, which means they sprout and grow a bulb in their first year. If the bulbs are not harvested in the first year then they sprout again the second year and send up a flower stalk and set seeds.
The problem with sets is the plants “think” they are in the second year if planted by set. So you have many more problems with flower stalks, and the bulbs never develop as large because the plants are focused on growing flowers and setting seeds.
Now don’t get me wrong, many people are very successful at growing onions from sets, but you are missing out on larger, longer lasting onions if you plant this way.
3. Planting onions using seedlings.
Planting onions using seedling is by far the best and most productive way of planting onions that I have found. Seedlings are simply small onion plants. They look like a smaller version of a “green” onion that you would buy for cooking. These onion seedlings are usually transplanted out into the garden when they are around 6 weeks old. These seedlings are this years plants, so you will find that they are focused on growing bulbs not flowers. Since I switched to planting onions using seedlings I only ever have maybe 1 or 2 onions that send up a flower head during the season. Many years I don’t have any that send up flowers.
My overall production of onions has also increased dramatically since I started planting onions using seedlings! I’m getting more than twice the over all weight in onions that I used to get! I also love that you can plant some of these onions for harvest as green onions and get an extra early harvest. We will take more about this in a bit!
How do you get Onions Seedlings?
There are three ways to get your onion seedlings.
First you can grow them yourself. Starting onion seedlings is fairly easy to do, but remember that your seedlings need to be ready to go out in your garden 6 weeks before your last frost. That often means you will be starting them in January or February.
Second, many nurseries and garden supply stores are starting to stock onion seedlings. The one thing you need to be aware of is onion seedlings only last about 3 weeks from harvest until they need to be planted. So if you figure they are already a week old by the time they arrive at the store, then you really need to hurry! Find out from your local garden shop when they will be receiving their shipment and go buy them right after they arrive, and then don’t waste much time getting them in the ground!
Third, you can buy them directly from the growers, online! This has been the best method for me. The grower that I buy from (Dixondale Farms) harvests and packs the seedlings right in the field and then ships them out to me. They arrive less than a week from being harvested and I can put them right back into the ground in my garden!
They also have the proper planting times worked out for my area so they are shipped to me at the exact time I should be planting!! Many growers will offer BIG discounts for bulk orders, so consider getting together with your neighbors or a local gardening club and making a bulk purchase. That often will get the price below $3.00 for a bundle of 60 plants!
Planting Onions using Seedlings
Planting out your seedlings couldn’t be easier. The seedlings simply need to be planted 1 inch in the ground.
And traditionally each onion needs about 4 inches of space. How far you space your seedlings will have quite a bit to do with the ultimate size of your onions.
You can break the 4 inch rule but you will end up with smaller onions as a result. Because our garden is laid out in beds that are 4 feet wide and 25 feet long, I prefer to plant my onions fairly close together and in a tight patch instead of long rows.
I plant 12 seedlings per row and each row is about 4 inches apart. This gives each plant roughly the 4 inches most guides call for. We prefer our onions to be about baseball sized (or smaller), we have found that this size of onion seems to last the longest in storage. So we are fine with this tight method of planting that yields a very big harvest of medium sized bulbs out of a very small amount of space.
The spot in the photo above had a yield of 40 pounds last year, that is very good for such a small space. And some years it will be as high as 55 pounds from the same space.
If you want larger bulbs (this is particularly true if you have planted a larger variety like Walla Walla) then you will need to give them more space. Go for 6 inch spacing between plants and 10 inches between rows.
If you would like some green onions to harvest very early in the season then you can cut your spacing down to only 2 inches. I also like to plant my green onions deeper. So these onions go in at around 3 inches deep. This method gives you a bit more of that long, blanched portion on the green onion that is so tasty!
Don’t get discourage by a lack of early growth, your newly planted seedlings will often need as much as 3 weeks before they really seem to come back to life! It takes that long for the roots to get established and for leaf growth to start. So be patient and keep your soil moist (but not soaking), if you aren’t getting any rain. After a few weeks those sick looking little sticks will take off and grow an awesome crop!
Onions are also BIG feeders, this means they need lots of fertilizer if you want big bulbs. You should fertilize with a fertilizer that is higher in phosphorous at the time of planting (10-20-10). After that you should fertilize every 3 weeks with a nitrogen fertilizer (21-0-0, or 15-0-0). Continue to apply this feeding every 3 weeks until the onions bulbs start to grow.
A word on fertilizer
As many of you know we are big organic growers. So we often skip the fertilizer all together, or if we do fertilize we just use an organic nitrogen fertilizer like fish emulsion (5-1-1). Not fertilizing does mean that we sacrifice size, but we make up for it by planting a TON of onions. There are organically certified fertilizers out there that you can buy if you would really like big onions. Another option would be to plant your onions in a bed that had legumes in it the year before, I always have much bigger onions if they are planted in a bed that had peas or beans in them the year before!
In case you can’t tell, I’m a big fan of planting onions using seedlings. I am so much happier with the quality, size and storage length of onions planted from seedlings than I am from those that I use to plant using sets!
If you would like more advice on growing onions I would suggest you take a look at my other two posts on the topic:
Seven Easy Steps for Growing Onions
Curing and Storing Onions for 10 months or more!