Seed Saving for the Alliaceae  Family

Genus

Species

Common Name

Allium

ampeloprasum

leek, elephant garlic

Allium

cepa

onion, shallot, multiplier onion, potato onion, top-setting onion

Allium

fistulosum

Japanese bunching onion, Welsh onion

Allium

sativum

garlic, rocambole

Allium

schoenoprasum

common chives

Allium

tuberosum

garlic chives

In a home garden situation most members of the Allium family are very easy to save for seed, because we collect the bulbs (garlic, potato onions, tree onions and shallots), store them and replant in Autumn/Winter or early Spring. Others we just keep on dividing up e.g. multiplying leeks and multiplying spring onions.
The only species we are likely to be collecting seed of are the leeks (ampeloprasum) or the seeding types of onions (cepa). As they cross within species this means we can only grow one variety from each species at a time.

Pollination:  Flies and bees are the primary pollinators, not the wind, of the seed bearing members of this family.

Isolation Distances: Isolation distances for seed saving from the seed bearing members of this family (onions, leeks, Welsh Bunching onions ) can be up to 5 km (“Seed to Seed”) depending on geography. My feeling is that 5 km applies when one is planting acres of seed and you’re on the Canterbury Plains with no hills or valleys! I find that far smaller distances work where you have populations of only 100 – 300 -1000, and you have small valley systems and loads of hills and trees. We’d love to hear of your experiences.
Minimum Numbers: For the seed bearing members of this family you’ll need to grow a minimum of 50-100 plants to  get seed of both the cepa and the ampeloprasum species. I would suggest you plant several hundred onions, mark the 50 -100 most true to type for seed saving and eat the rest. It works best to harvest all the onions in Summer, choose the best 50-100 for seed and plant them again in early August to go to seed. garlic, shallots Tree onions ad all members where you are using the swollen stems as your seed you can use simply the 1 best plant!

When To Plant: Plant onions for seed May – August .Plant bulbs garlic shallots etc from may to September depending on situation, check your local area.

Rogueing/Selection: For seed bearing members rogueing can be taken care of by eating those that are least true to type, at point of harvest. Everything that is not the usual shape, is to small or weak, or that does not die back and dry off well. With onions that are harvested when ripe in summer,  and hung up and stored before planting again to go to seed you can also choose only onions that stored well and that remained very hard.
With shallots, tree onions, potato onions, garlic etc., select your best bulbs as they are harvested to keep for your ‘mother’ seed. With Tree Onions and Shallots it is a good idea to look carefully at each onion you harvest and choose only those for seed that do not have the hard seed stem growing up through the onion, as well as the biggest and hardest. If you choose and select only those that have an external hard stem you will after a very few years have a far better line that you began with.

Support /Protection: None needed!

Harvesting: Onion seed can be harvested when the tops have fallen over and are dying back and going brown. I grade mine at this point into eating and seed saving. It’s easy to tell when to harvest the seed, just wait until the seed turns black in the seed heads, but make sure it doesn’t drop out. It always pays to harvest slightly early, and put in the greenhouse to finish drying, rather than lose to a rain storm in the Autumn.

Threshing:
Seed bearing members: Once the seed heads are dry and crunch, rub with your hands or dance on them on a sheet or tarp to remove the seeds.
Bulbs: We tie our garlic in bunches of 20 bulbs at a time and hang them with their stems etc all still on them, in an airy dry place to fully dry. This will take around a month. you can choose to leave the garlic hanging like this until needed however I prefer to go through and cut the tops off, and rub the outside garlic covers off to leave a clean shiny looking bulb. I then cut the roots off too and place all the top grade bulbs in an onion bag, with all the second grade left for eating in other bags.
Winnowing: Onion seed is very easy to winnow, simply let the seed and rubbish fall from one container to another in a gentle breeze or in front of a fan with a  sheet on the ground in front of the fan. Do this several times until you have clean seed.

Storage: Onion, garlic shallots etc can be either hung up in onion bags or strung  up, and hung in a cool, airy, dry, place.
These bags can remain all winter in an airy dry place.
Onion seed once dry and clean can be stored in an airtight container in a cool place.
Seed Life Expectancy: When stored in cool, dark, dry conditions, leeks will retain 50% germination for 3 years, onions for 2 years.