Onions for the Year Ahead
Updated: Mar 24, 2021
"The beauty of seeds is rivaled only by their purpose. Within the confines its seed coat, every seed holds a connection to the future and the past."
The Seed Garden, Section One
After a couple of seasons experience starting onions from seed, we began considering the importance of having our own, homestead-grown seed. By raising a small portion of our onion crop into seed for the next year, we are able to ensure that there is an abundant seed supply and, more importantly, that the seed is tailored to our specific habitat. Over time, this will allow us to selectively improve our crop.
The first step in growing seed onions is to evaluate which onions best meet the standards we are looking for. There are several key characteristics:
Our favorite variety of long-storage yellow onions reaches three to four inches in diameter when it is mature. As with any home-grown onions, there are many that never reach full maturity. A few will also exceed this limit, but they tend to split into separate bulbs, and frequently don't keep as well. When choosing which ones to save and grow into next year's seed, we look for onions that have fully matured and reached their potential, but that have not shown any tendency toward splitting into two separate bulbs or sending up a seed stalk prematurely.
Strong Protective Papers
For onions to handle and store well, they need to be tightly wrapped in strong skins. The best onions for next year's seed show good papers with no sign of disease or mildew.
Outstanding Keeping Quality
The onions we harvest in August of one year need to carry us through until we begin harvesting them again the following July. This means that keeping quality is a top priority. While the onions we use in June won't be as crisp as the freshly-harvested ones were the previous fall, they still should have good, strong flavor. (Some onions will always be lost; we don't weep for them. They go back to the compost, which will feed the soil another time.)
Ideally we would choose which onions were going to be our seed onions right after harvesting and store them in optimal conditions. Realistically, on a busy homestead there just isn't enough time or space to have two different storage arrangements for seed crops, so the seed onions are chosen from the best survivors when planting time rolls around in the spring. This is a good way to test for keeping quality, and it should--over planting generations--select for those that keep in the conditions we can actually provide.
A quick note on onion biology: Because onions are biennial, they produce seed during their second year of life. They bulb the first year, overwinter, and then produce a seed stalk the second year. (It isn't uncommon for onions grown from sets or even occasionally from seed to put up a bloom stalk during their first year, but this is a mutation that should be discouraged, as it ruins the keeping quality of the onions. These first-year seeders should never be saved for seed or used as a cross pollinator for your seed onions.) Before onions will go to seed, they need to meet their vernalization requirement: temperatures below 58 degrees Fahrenheit for eight to ten weeks. Because we store our onions in the chilly sunroom through the winter, that requirement is easily met.
Once the spring soil warms to at least 55 degrees Fahrenheit, the bulbs are ready to be planted. We put our seed onions in a separate area of the garden, well protected from deer and elk. Because the bulbs will need to draw more deeply on the soil for producing seed than they would if they were bulbing in their first year, they need space. For variety maintenance, it would be best to plant as many as fifty plants, but that wasn't feasible for us. This year we planted eight bulbs with twelve to fifteen inches of space on center between them.
As they near the end of their seed production cycle, onions are top heavy with their abundant seed heads and need to be caged or staked to prevent the seeds getting trampled or wet on the ground. When 20% of the seed capsules have split open to reveal the angular, black seeds inside, we cut the heads with with six inches of stem attached. These heads are turned upside down on plates indoors to finish drying and releasing their seeds.
After all of the heads seem completely dry, we beat them out or rub them between our hands to encourage the seeds to shake loose.
The pile of seeds and chaff that is left behind is easily cleaned by winnowing. Onion seeds are heavy enough that a gentle to moderate breeze will carry away the chaff without disturbing the seeds. As always with winnowing, it is important to judge the strength of the wind and adjust the distance between your hand (releasing the seeds) and the bowl underneath to find the correct gap. Once the seeds have been winnowed, they're spread in a thin layer on the plate and put in a dry place (near the woodstove is best) to ensure they haven't absorbed any moisture. When they're thoroughly dry, they are ready to be packaged, onions for the year ahead.