Phacelia (Lacy Phacelia) in Zone 4a & 4b
Phacelia tanacetifolia
Yes, phacelia (lacy phacelia) grows in zones 4a and 4b. Plant it outside Apr 24–May 1.
When to plant phacelia (lacy phacelia) in zone 4b
Zones 4a and 4b 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 | Apr 24–May 1 |
| Estimated bloom | Jul 3–Jul 10 (~70 days after direct-sowing) |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 2.5-3.5 ft.
Plant alongside it in zone 4b
These go outside within two weeks of phacelia (lacy phacelia) in zone 4b, so one planting day can cover them.
- Black-Eyed SusanApr 24–May 1
- Clarkia (Farewell-to-Spring)Apr 24–May 1
- Cynoglossum (Chinese Forget-Me-Not)Apr 24–May 1
- Purple ConeflowerApr 24–May 1
- Saponaria (Soapwort)Apr 24–May 1
- Shasta DaisyApr 24–May 1
Phacelia, also called purple tansy or lacy phacelia, is grown less for cutting than for what it does in the garden: it's an outstanding nectar source for honeybees and draws beneficial insects reliably wherever it's planted.
How phacelia (lacy phacelia) fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Phacelia (lacy phacelia) needs about 70 days from sowing to first bloom.
Phacelia (Lacy Phacelia) planting windows in every zone
Zone 4b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Bloom |
|---|---|---|---|
| 2a & 2b | Not usually | Apr 29–May 6 | Jul 8–Jul 15 |
| 3a & 3b | Not usually | May 9–May 16 | Jul 18–Jul 25 |
| 4a & 4b (your zone) | Not usually | Apr 24–May 1 | Jul 3–Jul 10 |
| 5a & 5b | Not usually | Apr 19–Apr 26 | Jun 28–Jul 5 |
| 6a & 6b | Not usually | Apr 4–Apr 11 | Jun 13–Jun 20 |
| 7a & 7b | Not usually | Mar 20–Mar 27 | May 29–Jun 5 |
| 8a & 8b | Not usually | Mar 4–Mar 11 | May 13–May 20 |
| 9a & 9b | Not usually | Jan 25–Feb 1 | Apr 5–Apr 12 |
| 10a & 10b | Not usually | Jan 9–Jan 16 | Mar 20–Mar 27 |
| 11a & 11b | Not usually | Dec 11–Dec 18 | Feb 19–Feb 26 |
Bloom dates are about 70 days after the sow or plant-out date.
Zone 2 sows before zone 3 here, which looks wrong and is not. USDA zones rank winter cold, not season length, and zone 2 is mostly interior Alaska, where hard winters come with warm summers. More on what a zone measures.
Good companions
No well-established companions for phacelia (lacy phacelia).
Where to buy phacelia seeds
True Leaf Market · High Mowing Organic Seeds (each supplier's phacelia seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing phacelia (lacy phacelia)" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 4b calendar · Plan your beds in the Garden Designer →
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Growing Phacelia (Lacy Phacelia) in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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