Asparagus in Zone 3a & 3b
Asparagus officinalis
Yes, asparagus grows in zones 3a and 3b and comes back each year. Plant it outside May 16–May 23.
When to plant asparagus in zone 3b
Zones 3a and 3b share the same average frost dates, so this page covers both.
Method: Direct sow: Direct-sow outside. It doesn't transplant well, or doesn't need the extra time indoors.
| Start indoors | Not typically started indoors |
|---|---|
| Direct sow / transplant outside | May 16–May 23 |
| Estimated harvest | First real harvest in year 3 |
Spacing: about 2 square feet per plant (square-foot-gardening spacing). Mature height: 4-5 ft.
Before you plant: Asparagus has a winter-hardiness note for zone 3b. See the details below.
Plant alongside it in zone 3b
These go outside within two weeks of asparagus in zone 3b, so one planting day can cover them.
- OnionMay 9–May 16
- RadishMay 2–May 9
- CarrotMay 9–May 16
- CabbageMay 16–May 23
- LettuceMay 16–May 23
- BroccoliMay 16–May 23
Asparagus asks for more patience than almost anything else in a vegetable garden. It's planted from a crown, not a seed, and the bed it goes into is meant to stay put for a decade or more rather than getting reworked each season.
How asparagus fits zone 3's season
Zone 3b's frost-free window runs about 98 days, from May 30 to September 5. Asparagus takes about 2 growing seasons to reach first worthwhile harvest, so what matters here is how many of these seasons it gets, not whether one is long enough.
Asparagus is hardy in zones 3-9, so in zone 3b it stays in the ground through winter and comes back rather than being replanted. Allow about 1.5 ft of spread at maturity.
Asparagus planting windows in every zone
Zone 3b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Harvest |
|---|---|---|---|
| 3a & 3b (your zone) | Not usually | May 16–May 23 | First real harvest in year 3 |
| 4a & 4b | Not usually | May 1–May 8 | First real harvest in year 3 |
| 5a & 5b | Not usually | Apr 26–May 3 | First real harvest in year 3 |
| 6a & 6b | Not usually | Apr 11–Apr 18 | First real harvest in year 3 |
| 7a & 7b | Not usually | Mar 27–Apr 3 | First real harvest in year 3 |
| 8a & 8b | Not usually | Mar 11–Mar 18 | First real harvest in year 3 |
| 9a & 9b | Not usually | Feb 1–Feb 8 | First real harvest in year 3 |
Good companions
- Tomato: Asparagus roots contain asparagusic acid, shown in lab studies to be nematicidal against root-knot nematode, a real threat to tomato. The classic pairing has real chemistry behind it, though the studies test the extract's effect on the nematode directly rather than measuring an outcome from interplanting the two in a shared bed.
Where to buy asparagus seeds
True Leaf Market · Burpee (each supplier's asparagus seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing asparagus" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 3b calendar · Plan your beds in the Garden Designer →
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Growing Asparagus in USDA zone 3b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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