Alliums: Onions, Garlic, Leeks & More
Save seeds from onions and leeks, or propagate garlic from cloves.
Overview
Alliums include onions, leeks, garlic, shallots, and chives. Garlic is typically grown from cloves rather than seed. Onions and leeks are biennial and cross freely within species. The beautiful round flower heads (umbels) produce many small black seeds.
Crops Covered:
insect-pollinated
dry processing
2-4 weeks in paper bags
Onions: 1-2 years (short-lived!)
Understanding Pollination
Onions and leeks are insect-pollinated. All onion varieties will cross with each other.
Isolation Distance
1/2 mile for onions and leeks
Key Tips:
- Onion varieties cross freely - isolate or grow one variety
- Leeks cross with other leeks
- Can cage and introduce flies for isolation
- Garlic is clonally propagated (not from seed)
- Shallots can be grown from seed or division
Step-by-Step Guide
Choose best onions in fall, store overwinter, replant in spring.
- Select firm, healthy, typical bulbs
- Store in cool (35-45°F), dry conditions
- Plant out early in spring
- Bulbs will send up flower stalks
- For leeks, can leave in ground if climate allows
Wait for flower heads to fully bloom and set seed.
- Round flower heads (umbels) form on tall stalks
- Flowers open gradually over 2-3 weeks
- Bees pollinate the flowers
- Seeds develop as flowers fade
- Stalks may need staking to prevent falling over
Cut heads when black seeds are visible.
- Seeds turn black when ripe
- Some seed will show when flowers dry
- Cut heads when about 50% of seeds are visible
- Place upside down in paper bag to dry
- Seeds will fall into bag as they dry
Separate seeds from dried flower parts.
- Rub heads to release remaining seeds
- Winnow or screen to remove chaff
- Seeds are small, black, and angular
- Remove any debris or light seeds
Harvest Timing
| Crop | Harvest Stage | Days After Flowering |
|---|---|---|
| Onions | Black seeds visible, heads drying | 40-50 days |
| Leeks | Seeds black, some shattering | 45-55 days |
| Chives | Flower heads dry, seeds dark | 30-40 days |
Processing: Dry Method
Let flower heads dry, then shake/rub to release seeds.
- 1Cut heads when seeds begin showing
- 2Dry upside down in paper bags
- 3Rub dried heads to release seeds
- 4Winnow to remove chaff
- 5Screen to clean further
Drying & Storage
2-4 weeks in paper bags
Warm, dry location with good airflow
Test for Dryness: Seeds hard and black, heads completely papery
Paper envelopes, Glass jars
Cool, dark, dry. Onion seed has shorter life than many vegetables.
Onions: 1-2 years (short-lived!), Leeks: 2-3 years
- IMPORTANT: Onion seed has short viability - use fresh seed!
- Store in refrigerator for best longevity
- Test germination rate for any seed over 1 year old
- Garlic: simply save best cloves for replanting
Vegetative Propagation (Recommended)
Garlic is almost exclusively propagated from cloves, not seed. Shallots can be grown from sets. Onions can be started from sets, transplants, or seed. Understanding these vegetative methods is essential for allium gardeners.
Why Vegetative Propagation?
Garlic rarely produces true seed (and when it does, requires 2+ years to bulb). Clove planting ensures variety integrity and produces full-sized bulbs in one season.
How to do it:
- 1Select the largest, healthiest bulbs for planting stock
- 2Break bulb into individual cloves just before planting
- 3Leave papery skin on cloves
- 4Plant cloves 2 inches deep, pointed end UP
- 5Space 6 inches apart in rows 12 inches apart
- 6Mulch heavily with 4-6 inches of straw
- 7Harvest following summer when lower leaves brown
How to do it:
- 1Harvest bulbils from scape flower heads when papery
- 2Plant bulbils 1 inch deep, 2 inches apart
- 3First year produces small "round" (single clove)
- 4Harvest rounds and replant in fall
- 5Second year produces small bulb or larger round
- 6Full-sized bulbs typically by year 3
- 7Use to increase stock without sacrificing eating bulbs
How to do it:
- 1Select firm, medium-sized bulbs
- 2Separate clustered bulbs if present
- 3Plant 1-2 inches deep, pointed end up
- 4Space 4-6 inches apart
- 5Each bulb multiplies into a cluster
- 6Harvest when tops fall over and dry
- 7Save medium bulbs for replanting
How to do it:
- 1Dig up established clump
- 2Divide into sections with roots attached
- 3Each section should have 5-10 bulbs/shoots
- 4Replant immediately at same depth
- 5Water well and keep moist
- 6Plants establish quickly from divisions