Yarrow in Zone 4a & 4b
Achillea millefolium
Yes, yarrow grows in zones 4a and 4b. Start seeds indoors Mar 13–Mar 20 and plant out May 15–May 22.
When to plant yarrow in zone 4b
Zones 4a and 4b share the same average frost dates, so this page covers both.
Method: Either: Start indoors for an earlier harvest, or direct-sow outside for less fuss. Either works.
| Start indoors | Mar 13–Mar 20 |
|---|---|
| Direct sow / transplant outside | May 15–May 22 |
| Estimated bloom | Aug 23–Aug 30 (~100 days after planting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 2-3 ft.
Plant alongside it in zone 4b
These go outside within two weeks of yarrow in zone 4b, so one planting day can cover them.
- NasturtiumMay 22–May 29
- MarigoldMay 22–May 29
- African DaisyMay 15–May 22
- Amaranthus (Love-Lies-Bleeding)May 15–May 22
- Ammi (False Queen Anne's Lace)May 15–May 22
- Ammobium (Winged Everlasting)May 15–May 22
Yarrow is a hardy perennial known for its flat-topped flower clusters and its toughness once established. It tolerates poor soil, drought, and deer browsing better than most garden flowers.
How yarrow fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Yarrow needs about 100 days from sowing to first bloom.
Yarrow 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 |
|---|---|---|---|
| 3a & 3b | Mar 28–Apr 4 | May 30–Jun 6 | Sep 7–Sep 14 |
| 4a & 4b (your zone) | Mar 13–Mar 20 | May 15–May 22 | Aug 23–Aug 30 |
| 5a & 5b | Mar 8–Mar 15 | May 10–May 17 | Aug 18–Aug 25 |
| 6a & 6b | Feb 21–Feb 28 | Apr 25–May 2 | Aug 3–Aug 10 |
| 7a & 7b | Feb 6–Feb 13 | Apr 10–Apr 17 | Jul 19–Jul 26 |
| 8a & 8b | Jan 21–Jan 28 | Mar 25–Apr 1 | Jul 3–Jul 10 |
| 9a & 9b | Dec 14–Dec 21 | Feb 15–Feb 22 | May 26–Jun 2 |
Bloom dates are about 100 days after the sow or plant-out date, not after starting seeds indoors.
Good companions
No well-established companions for yarrow.
Where to buy yarrow seeds
True Leaf Market · High Mowing Organic Seeds (each supplier's yarrow seeds)
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See it growing
Search YouTube for "growing yarrow" 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 Yarrow in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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