Asparagus in Zone 9a & 9b
Asparagus officinalis
Yes, asparagus grows in zones 9a and 9b and comes back each year. Plant it outside Feb 1–Feb 8.
When to plant asparagus in zone 9b
Zones 9a and 9b 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 | Feb 1–Feb 8 |
| 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 9b. See the details below.
Plant alongside it in zone 9b
These go outside within two weeks of asparagus in zone 9b, so one planting day can cover them.
- OnionJan 25–Feb 1
- RadishJan 18–Jan 25
- CarrotJan 25–Feb 1
- CabbageFeb 1–Feb 8
- LettuceFeb 1–Feb 8
- BroccoliFeb 1–Feb 8
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 9's season
Zone 9b's frost-free window runs about 293 days, from February 15 to December 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 9b 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 9b 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 | 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 (your zone) | 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 9b calendar · Plan your beds in the Garden Designer →
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Growing Asparagus in USDA zone 9b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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