ONIONS

Onions are a big deal for me & my garden. I can’t really do without onions. Onions for everything: soups, stews, casseroles, sauces, salads, sandwiches, eggs & quiches, you name it. The onions I had grown in our previous garden (5,200′) 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, so I thought onions should be easy to grow and as I started the garden that first year here I expected success. My, oh my. I was in for a few years of trial & error & error & …. Well, you get the idea.

The first year I planted around 40-50 onions using the same method I’d used previously. I started the onion from seed indoors in soil blocks the first part of April and transplanted them outdoors mid-May. All I got for my efforts were a few bulb-less, fat green onions. I realized I needed to come up with a better plan!

ONION GROWING TRIALS

Over the years since then I’ve tried several different experiments:

I tried planting seeds in the ground in the fall. Some of these did fairly well. I was rewarded with small, but decent bulbs.
I tried “overwintering” onions by starting overwintering varieties from seed around 8/1 to grow to bulbs in the spring. These grew to about the size of an ice pick spike by mid-September. They were mulched well over for the winter, and all died before the following spring. Perhaps these would have lived if started sooner to get larger before winter set in, or if they were given protection over the winter. However, I’m not optimistic that this would work.
I tried planting a few for overwintering in our cold frames, but they succumbed in the cold.
I ordered some onion plants for transplanting from Dixondale Farms in Texas. I followed their planting instructions exactly and used their fertilizer. These were the best onions I’d grown here to date.

After the success I’d had with the onion plant starts I’d ordered, I thought, “I can grow onions to this size myself, from seed.” I started onions the next year on February 1 in the greenhouse. By mid-May these healthy, small plants were about the same size as the Dixondale plants I’d ordered previously. These were planted about 4” apart in rows 15-16” apart, with a trench between the rows to be filled with fertilizer at planting and occasionally thereafter. This is my best (and cheapest) method yet.

ONION HARVEST

Please note that high-elevation onions take longer to grow than those grown in better locations. I keep them in the garden as long as possible, but sometimes have to bend over the tops to get them out of the ground prior to a predicted snowstorm. Fall frost does not damage the onions unless it is extremely cold. My onions are generally harvested between 125-140 days after transplant to the garden, and this is after they’ve grown about 100 days in the greenhouse. Sorry, I just haven’t come up with a better way.

ONION DAYLENGTH

Some words about day length. We are located at latitude 38.77. The best day length here for onions is “Intermediate Day” and I also have had success with one “Long Day” onion, Clear Dawn. It is important to know the day length for your own latitude. Many of the onion seeds I find will specify which latitudes are best, and I generally go by that recommendation. A good day-length map can be found at Dixondale Farms.

Note: In 2023 I tried to grow “Dakota Tears”, another Long Day variety. These did not do well at all. I ended up with a whole row of bulbless onions.

HOW TO GROW HIGH-ELEVATION ONIONS

Choose day-length seeds specified for your latitude.
Start seeds indoors early, at least 14-15 weeks before transplanting outdoors, about 18 weeks before your “last frost date”, in greenhouse beds, trays, or soil blocks.
Onions in Greenhouse Bed, Ready to Transplant
Keep the onion tops trimmed to about 5-6” tall.
Prepare your outdoor soil (raised beds or in-ground) by adding 1-2” compost and an all-purpose vegetable fertilizer a few days prior to transplanting, or when soil can be worked. Use a little less fertilizer than what the product recommends.
Transplant outdoors 2-3 weeks before your “last frost date”, when onions are at least the width of an icepick spike.
Carefully remove onion transplants from your greenhouse beds or trays used to start the seedlings just before planting.
Onions should be planted about 4” apart, in rows 15-16” apart, with a trench about 4” deep between the rows to be filled with fertilizer.
Fill the trench with an organic fertilizer especially formulated for onions. 10-20-10, or something relatively high in phosphorus.
Onions Growing in Raised Bed, Trench in Center
Water onion transplants right away and keep them watered regularly.
If snow or a deep freeze is expected, protect onions with frost cloth suspended above them like a tent, or with plastic stretched across hoops over the onions. A little snow shouldn’t hurt them after they’ve been in the ground a couple of weeks.
Every 3-4 weeks, add a fertilizer high in nitrogen to the trench.
Keep onion plants free from weeds.
If any onions begin to bolt, cut off flower stalks as soon as possible. Eat these onions first; they won’t store as well.
Harvest onions after their tops turn brown and/or bend over. If a deep freeze or snowstorm is predicted, bend over the tops a few days in advance, and harvest prior to the storm. Onions will not be damaged with a few light frosts.
Cure onions indoors if it will be below freezing outdoors. A greenhouse or non-freezing garage or basement will do. Please refer to another resource for how to cure your onions.
After curing, store onions in a root cellar or other cool, dark, well-ventilated location.

ONION STORAGE

After curing, we keep onions in the upper section of our Cold Closet. The upper section is insulated from the lower, and is a bit warmer and dryer, with ventilation provided by holes in the outer walls. It runs in the mid-40’s in the winter to 50’s in the spring. If I have enough onions, they store nicely until the following spring.