Growing Onion Sets
(An Ongoing Experiment)

Dateline: 9 January 2016 AD

Copra onions in my 2015 garden

Those who have read this blog for long know that I like to grow Copra onions. They do well in my soil and you will not find a better storage onion. I typically grow 300 to 400 Copra onions every year. 

In past years I have bought onion sets from Dixondale Farm is Texas. I have no complaints with their onion sets. But I have long thought that I should try growing my own onion sets from seed, and last year I finally got around to doing it. 

After pondering on the specifics of how to grow my own Copra onion sets, I came up with my own unique idea, and this blog post is an introduction to that idea....

I pretty much invented the concept of tri-growing onions in thin black plastic mulch over a garden bed, as seen in my "4-Day Carrots" series on YouTube. My success with tri-growing carrots in 3" diameter holes in black plastic  (started under shade discs) led me to try growing parsnips in a similar manner, and the results could not have been better (I'll blog about the parsnips soon). So I started thinking about what other crops I could adapt to the circular cutouts in plastic mulch, and onion sets came to mind.

I determined that mid-July would be the best time to start the onion sets. The idea being that I get them started in 2015, have them grow to a small size, pull them in the late fall, store them for the winter, and replant them in the spring. Specifically, I planted the onion seeds on July 20. 

The plastic mulch had been in place over the garden bed since May 6th when I made the cutouts and planted the onion seeds. The soil under the plastic was soft, moist and weed free. 

I planted 10 seeds in each 3" diameter cutout. I used a homemade template and dibble, as you can see in the following picture, to make 10 evenly spaced indents for 10 onion seeds.

(click pictures to see enlarged views)

In this next picture you can see the dibbled indents, and if you look close you can see a single onion seed in each one.

Then I filled the indents with fine vermiculite (picture below). I've come to the conclusion that vermiculite is the ideal seed covering for this sort of thing. Last year I bought a large bag of fine vermiculite from ULINE. Since I only use a little every year, the big bag will last me a very long time.

This next picture shows all the circular plantings in a section of garden bed. 500 onion seeds were planted in that small section of garden bed. The seeds came from Territorial Seed Company. A 2-gram packet cost me $6.75.  I only used about half the packet.

I covered the just-planted section of bed with a piece of coffee-bag burlap that Marlene picked up at the local thrift store for a dollar. The burlap protected the seeds from being displaced in a heavy rain, and it allowed me to water over the plantings without creating any disturbance.

Eight days later, some onion seedlings were emerging and I removed the burlap. On August 9th, most all of the onion seeds had germinated and were 2" to 3" high. They were inconsequential looking little filaments of green, but they were on their way.

I lost track of dates but this next picture shows the onion circles some time later. They grew very well. I did not water them once established. No thinning was needed, and there was no weed competition.

This next picture shows the onions a little further along, and the close-up shows how healthy and beautiful the young onions were.

In late November the onions were pretty big. Maybe they were too big. I really don't know (remember, this is my first time trying this).

This next picture shows what they looked like after I pulled them up...

I decided the best way to keep them through winter was to clamp them right in the garden. So I dug a shallow hole and layered all the onions on a bed of dry leaves...

Then I covered the onions with some straw...

Then I piled some soil on top and flagged the clamp...

There is snow on the ground here now. I'm hoping the onion sets will get through winter in good enough shape to plant early in the spring, and that that I'll get a great crop of storage onions next year. 

This is all an experiment. I'll modify it as needed until I have a system that works best for me. For example, I don't think I really want the sets to be so big in the fall. So I'll plant the seeds a week (or even two weeks) later than July 20th next time I do this. And if the clamp doesn't work as well as I think it should, I'll try another idea. 

That's a lesson in gardening for you. The point being, you experiment with different ideas and fine tune your own gardening systems. This sort of thing can take a lifetime to do.

I'll keep you updated on this idea through next year.

Stay tuned...

Some of the 2015 harvest


Unknown said...


This is also one of our first years to seriously grow bulb type onions from seed. Because we live so far south (about 20 miles from the Gulf of Mexico, in Louisiana), ours can be direct seeded in mid to late fall and left in the ground straight through the winter. We tried directly seeding into our garden last year, but got mixed results with spotty germination and weed troubles. This year, we used 2 old cow troughs filled with a mix of compost and soil that we could better manage. So far they are looking great, and we plan to transplant some time this month. I'm eager to hear how yours turn out once transplanted. I enjoy reading your blog very much - keep the posts coming! By the way, our Whizbang chicken plucker worked great. We ordered the Shebang package in early fall and got it finished just in time to process our 150 broilers. It never missed a lick!

ELittle said...

Hi Herrick, What is the spacing of the ten holes in the disc? I often wondered when the seed companies started growing their sets, but never tried to figure it out. I started a tray of 200 in one 12x18 tray a couple of winters ago in November and by planting time they were a solid block of intertwined roots and tops. That didn't work out to well . So using your experimental ideas I'm going to start another bunch Shortly and see how it all turns out. Also going to be using Eliot Coleman's soil blocking ideas for a lot of small seed stuff to see how that goes. Bought all the stuff I need last fall ,so I'm good to go. Getting antsy already. Tried a clamp as you do them and put in about 50 carrots. Hope it works because it has NOT been cold down here yet! Love the posts, Keep 'em coming! Best, Everett

RonC said...

And then all you need to do is bury a couple of your big onions over winter and have them come up in the spring and bloom and produce seed and you would have a sustainable onion supply. Onion flowers are beautiful and the bees LOVE them. I've only grown onions from seed once and figured they were a bit fiddley so I just buy sets every year and grow from there. Only problem is that you have to settle for what the store is selling. I will have to try this experiment and see if I can cross onions off my have to buy list once and for all. I have the beets, carrots, green beans and tomatoes figured out.


Herrick Kimball said...


Only problem is that the Copra is a hybrid. I need to experiment with some different onion varieties that are OP on a small scale to see if I find one I really like. You’re doing really good if you are saving your own carrot and beet seed.

dfr2010 said...

This is an interesting experiment! I'll need to mull over it to see what is applicable to my deep-south Florida sand, but I do feel a spark of inspiration in there.

Unknown said...

I can't wait to see how they do! I have been working with a few different onions, but since they're heirloom, you won't find any like the large ones in the store or the ones you grow from hybrid seed. The first one was Egyptian Walking Onions, and boy do they ever walk, they plant themselves by bending over and planting themselves again, however they are small, and you need a lot of them. (they do grow a lot of them) I have a few others that I will be starting this year. I have a video on the Egyptian Walking Onions, and will post it when the other ones are started. I hope to be able to have a constant store of onions that I can save for a year to year harvest.

Herrick Kimball said...

Sparks of inspiration. I like that.

I grew the Egyptian onions long ago, but Marlene didn't use them. I think I need to try growing them again. The perennial aspect appeals to me. I'll go look for your video. Thanks for the insights.

Anonymous said...

Wow - that seed set is a work of art.
Regards - Muns

deb harvey said...

ask everett if he will report how the carrot clamp did in this year's weather and in his growing zone. thanks.

RonC said...

Whew! good catch. I was just about to send in my order for some Copra Onion seeds. Was just holding off until I had time to browse through the rest of the Territorial seed catalog in case there was something else I wanted. I guess Yellow Stuttgarter from John Scheepers or Dakota Tears from Seeds of Change are the only options I see so far. I have some Yellow Stuttgarters sitting in the farmhouse basement that I grew from sets last year. I am doing a storage test on them and will dehydrate them if they don't keep until Spring. I have found in the past that onions can get half mushy and still be useful for growing onion seed the next year.

The beets and Carrots are pretty easy to grow to seed. I just take the biggest roots and replant them in a corner of the garden when I dig both in the Fall. You will have problems with maintaining genetic purity with the carrots if you have Queen Anne's lace in the neighborhood. Also, it is best to only grow out one variety a year for seed. A couple of roots will generate several years worth of seed. The biggest problem is protecting the roots from the deer, but I have a solar powered electric fence around the garden now.


Elizabeth L. Johnson said...

Wow, so nice to learn from you and your readers, Herrick.

Anonymous said...

Wow, this seems like a lot of work for onions; first growing the sets and then having to replant those in the spring. I live in Canada (Zone 4-5) and have never used onion sets. Starting seeds early inside, with 4 seeds in each 1" planting block means that I can just plant the seedlings outside a few weeks before last frost (I plant them in the bunches with wider spacing since that's how they grow naturally). And by the end of summer I have huge onions. I'm still looking for a good open pollinated yellow storage onion myself. When I have experimented with sets at the same time, the onions from seed do just as well, if not better.

Anna said...

What are your reasons for not simply direct seeding the onions in early spring? I am in zone 4 (South Dakota) and started doing this 2 years ago after using sets for many years. I have had better results direct sowing than I have using sets. My onions have plenty of time to grow large enough in one growing season.

Herrick Kimball said...

Anonymous and Anna—

I'm in a zone 4-5 here in NY and I've never known anyone around these parts to direct seed onions. I'll give it a trial in the spring.

The longer growing season for onions, the better. Anna, can you direct seed tomatoes in ND? I've had some success with that here.

Planting multiple seeds in soil blocks indoors (I think I've seen this in Eliott Coleman's books) and keeping them watered is time (and space) consuming too. But more than that, I've always had my best success growing seedlings outdoors, in direct contact with the earth and in full sun (I can't get full sun indoors).

My technique here is only time consuming at the start, when planting. There was no watering or weeding after that. Pulling the onions and clamping them in the garden was easy and fast. If they come out in good shape in the spring, I'll have green sets, which is exactly what I've been buying from Dixondale Farms for so many years.

My original intention was to grow dry onion sets as explained in Dick Raymond's book, "The Joy of Gardening." Raymond gardened in Vermont. He tells how he grew 45 pounds of sets from one ounce of onion seed, in a 3x5 area of his garden. That's remarkable!

He plants in July, then pulls the marble-sized plants after a freeze, and dries them down indoors. Then they are ready to plant in the spring.

I didn't use his exact technique but I used his basic concept—planting in July for harvest in the late fall. But when I brought some of the onion plants indoors to dry them down, they didn't dry into a nice round bulb. Then I re-read his instructions and he says that Ebenezer, Stuttgarter, and Buccaneer seeds produce excellent sets. Not all onions are the same.

I'm definitely going to try the direct seeding approach. And maybe I'll try direct seeding in a cold frame in early spring, perhaps in multi-seeded soil blocks set into the ground just a bit. Thanks for the ideas.