I can’t really do without onions. Onions for everything: soups, stews, casseroles, sauces, salads, eggs & quiches, you name it. The onions I had grown in our previous garden all did wonderfully. I had no reason to believe they would not do well here at 9,000 feet. I’d read on a local county resource list that other gardeners had success with some of the same varieties I’d grown before, and I still had some seeds, so I tried those my first year in this garden. I expected success. I planted around 40-50 onions using the same method I’ve used before. Not a good idea. Dang. Wimpy little things that didn’t make much of a bulb. In this climate they just didn’t get a long enough or warm enough season.

After trying several different methods of growing onions at high altitude the past four years, I think I’ve found the BEST! It takes a little extra effort, maybe a few extra $$, some TLC, but it CAN be done.

Below are some of the experiments I’ve tried to produce the BEST onions in this location. This has been quite an education in high elevation onions! Hint: The best method is the last. 


August 2017 Onion

I thought I did what was right. I did what was successful at lower elevation. I have always started my onions from seed, and have always had good success. Here, I started onion seedlings 10 weeks prior to the last frost date and expected to be able to plant them outside at that time or sooner. These were all started in soil blocks, and I transplanted them outside at about 7 weeks after starting. The weather had been so nice, I planted them out, kept them covered at night, and I thought they would do fine. Not. Too cold? Too soon? I didn’t think so; I know onions can handle the cold and can be planted out before last frost. They didn’t die, but did the colder weather stunt their growth? By the end of the season, a few of them had small bulbs that were maybe 2-3″ across. The rest were smaller, some with no bulbs. The stalks never really fell over. I ended up bending them over myself. I kept them mulched well and in the garden until finally, in October, before it seriously froze (but after several nights below 32), I pulled them all out of the ground to cure on racks in the greenhouse. Very few of them cured as usual–the tops never dried up. The thick stalks remained green and some continued to grow. I was able to cook with them–since they were so small it didn’t take long to use them up before they spoiled.

As I mentioned earlier, the leeks and scallions all did well. I was very glad to have them! I used the leeks until I was afraid they might go rotten, and before they did I froze the remainder and used them later. Most of the scallions I planted were “Evergreen Hardy”, a multiplier onion. I left most of them in the ground all season, and they really multiplied! I ended up with too many all at once. I left some in the ground over the winter, and they all came back in the spring to multiply even more.

I also attempted to grow a few onions in the greenhouse. They took a very long time to grow and never really made bulbs. Leeks grew slowly and were ok, but since it took almost an entire year to get to normal leek size I will probably only grow them outdoors from now on. Leeks will be another page, another day.


Some words about day length. The best “day length” here for onions is apparently “Intermediate Day.” We are at latitude 38.77. Many sources suggest that we can successfully grow either Intermediate-Day or Long-Day onions in this region. Our former location in Wellington was latitude 40.73, where I grew both long-day and intermediate-day onions which bulbed up nicely. According to Dixondale Farms, all of Colorado should be growing intermediate-day onions, and suggests that both daylength and temperature trigger the transfer of forming leaves to bulbing. Garden.org suggests that anywhere above latitude 35 degrees should grow long-day onions, and that “day neutral” or “intermediate day” onions are bred to be less sensitive to day length. Other sources suggest that anything north of either the 37th or 38th parallel should be “long day”. For the most part, I try to stick with “Intermediate Day” varieties.


As for my “continuing education”, every year I try a few new onion experiments. I’ve had mixed results, with a couple of new things I’m trying for 2020.


Seeds planted Fall 2018 || Harvested Summer 2019

In the fall of 2017, I put just a few “Clear Dawn” (Long Day) onion seeds in the ground, topped with mulch over the winter. Sure enough, in spring they sprouted, and I waited to see how well they would grow. I’d also started seeds indoors, as usual, so I planted those in different locations as well. At the end of summer 2018, the seeds planted the previous fall had done better than those started indoors and transplanted. The bulbs were still somewhat small, but they were more “bulb-ish” and the tops fell over and dried better than the others.

Based on this experience, I dedicated an entire bed in the fall of 2018 to plant onion seeds for 2019. Those did not all do well, but far better than my experience of starting seeds indoors for transplant. Less work, less space taken up under lights or in the greenhouse for the seedlings. This was my new preferred method.


I also tried THIS METHOD of starting seeds for transplant, taking advantage of natural light and the warming of the season to grow onions more “naturally”. In the end, it was still a little more effort and the results were no better than just planting the seeds in the ground in the fall. I’m not really sure of the advantage of this method, unless for some reason the space is just not available in the fall.


After reading about the concept of “overwintering” onions, I decided to try that. I received an email from Territorial Seed explaining briefly that,

“Onions that are started in late summer will yield mild, succulent harvests in spring if properly grown. Timing is everything for overwintered onions, which can be a little tricky and depends on your particular climate. The goal is to start your seeds in trays, allow the plants to reach the approximate size of a pencil prior to transplanting in fall. The plants will then go dormant through the coldest months and resume growing when the days warm up.”

They go on to explain that in their area in Oregon, they sow their seed in late July or August, allowing the plants to size up to about ¼” wide by Sept/Oct. I could not locate this information on their website.

I’m not sure why they start these seeds indoors to transplant out later, unless it’s due to space availability outdoors at that time. I also wasn’t sure when I’d need to start these seeds in my area. I went ahead and purchased some onion seeds that are supposed to be good for overwintering: Gate Keeper F1, Desert Sunrise F1, and some shallots, Ambition F1. I also had some Walla Walla seeds on hand, so tried those as well. The end of July, I planted one bed in my garden with these seeds. By the end of October, they were growing nicely, but less than pencil-sized. They were thicker than a toothpick, more like the size of a bamboo kabob stick. These were mulched heavily by mid-October prior to expected low temperatures and snow. I also planted a few seeds in another bed at that time, also mulched well. 

As of mid-May the garlic had begun to grow, the onion seeds planted in the ground had sprouted, but no sign of these overwintered onions. Finally, by the third week in May I decided to give up on them. I dug around and found no sign of them in the soil. This bed was then given to more carrots, cauliflower & cabbage.


Now that we have cold frames outdoors, I tried planting a few seeds in the cold frame in January for transplanting in the spring. These should have the benefit of natural light, cold temperatures overnight in the winter, and added warmth in both winter and spring during the day.
THE RESULT: These seeds never sprouted, or if they did, they may have been eaten by something. I suspected mice may have gotten in to the cold frames.



In early April I feared there may not be many onions that season–the “overwintered” onions didn’t appear to be growing, I had more bed space due to the removal of several non-producing berry plants, and decided that the only thing I’d really like more of would be onions.

I ordered some dormant onion plants from Dixondale Farms in Texas, to be planted in the ground here early May. Not to be confused with onion “sets”, these are plants grown to a small size then forced into dormancy. I ordered their “Intermediate Day Sampler Pack” of three different intermediate-day onions. These had a good amount of growth prior to planting (more growth than I’ve ever achieved in soil blocks growing 10-12 weeks). I also ordered their special fertilizer formulated especially for onions.

The Dixondale onions were planted May 1 and grew nicely. I followed all the instructions sent along with the order from Dixondale. The onions were harvested September 6, just prior to our first snow storm of the season. These onions did suffer from damage from the mice & pack rats nibbling on them, but even after the tops had been chomped off, they continued to grow. They would have been larger, I am sure, without the early damage. I only regret that I hadn’t planted more of them, and will allow more space for onions in years to come.

These are the best onions produced here so far. I will stick with this method in the future. I’ve wondered how I might do this myself, rather than order them online, but without the Texas weather, I don’t think it’s possible. My greenhouse doesn’t have the space I would need for this project, and with all my efforts I’ve never been able to produce an onion plant to the necessary size in the greenhouse or under lights. Onions must prefer the outdoors.

These are the varieties I’ve grown (or attempted) here in Guffey.

All started indoors, transplanted spring, harvested fall. None did very well.
Clear Dawn – 104 Days – Long Day – One of the better onions I’ve tried.
Copra – 104 Days – Long Day – Similar to Clear Dawn.
Sedona F1 – 108 Days – Long Day
Walla Walla – 100-150 days – Long Day
Red Torpedo – 110 Days – Intermediate Day

All started indoors, transplanted Spring, harvested Fall
Clear Dawn | 104 Days | Long Day – One of the best. Some sown Fall 2017 did better.
Expression F1 | 98 Days | Intermediate to Long Day – One of the best
New York Early | 98 Days | Long Day – Did not do well at all.
Cabernet Red | 90 Days | Intermediate Day – One of the best
Rossa Lunga di Tropea OP | 110 Days | Intermediate to Long Day – Did not do well

Most started outdoors Fall 2018, Harvested Fall 2019
Clear Dawn | 104 Days | Long Day – One of the best.
Expression F1 | 98 Days | Intermediate to Long Day – One of the best
Cabernet Red | 90 Days | Intermediate Day – One of the best
Rossa Lunga di Tropea OP | 110 Days | Intermediate to Long Day – Better this year, but still not worth doing again.

Sown August 1, 2019 for overwintering (none survived the winter)
Gate Keeper F1 | 250 Days | Intermediate Day 
Desert Sunrise F1 | 100 Days (if spring sown) | Intermediate Day
Walla Walla | 125 Days (if spring sown) | Long Day
Ambition F1 Shallot | 120 Days

Sown Fall 2019 (a few sprouted in May, most were eaten by mice)
Expression F1 | 98 Days | Intermediate to Long Day

Sown in Cold Frame, January 2020 (none of these sprouted)
Clear Dawn | 104 Days | Long Day
Expression F1 | 98 Days | Intermediate to Long Day 
Cabernet Red | 90 Days | Intermediate Day 

Dixondale Farms Intermediate Day Sampler, Dormant Plants, Transplanted May 2020
Candy | 90-100 Days | Intermediate Day | DTH: 128
Superstar | 95 Days | Intermediate Day | DTH: 128
Red Candy | 85-95 Days | Intermediate Day | DTH: 128

*DTH: Days To Harvest 9/6. The bulk of the harvest was September 6. A few of these were harvested and eaten prior to this date.