Hyssop in Zone 4a & 4b
Hyssopus officinalis
Yes, hyssop grows in zones 4a and 4b. Start seeds indoors Mar 20–Mar 27 and plant out May 22–May 29.
When to plant hyssop 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 20–Mar 27 |
|---|---|
| Direct sow / transplant outside | May 22–May 29 |
| Estimated harvest | Aug 15–Aug 22 (~85 days after planting) |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1.5-2 ft.
Plant alongside it in zone 4b
These go outside within two weeks of hyssop in zone 4b, so one planting day can cover them.
- BasilMay 29–Jun 5
- BorageMay 15–May 22
- RosemaryMay 29–Jun 5
- DillMay 8–May 15
- CatmintMay 22–May 29
- Citronella Plant (Mosquito Plant)May 22–May 29
Hyssop is a woody, semi-evergreen perennial in the mint family with a strong, minty-bitter flavor that's historically shown up more in liqueurs like Chartreuse and in potpourri than in everyday cooking. It's grown as much for its spikes of blue flowers and the bees they attract as for any culinary use.
How hyssop fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Hyssop needs about 85 days from sowing to first harvest.
Hyssop 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 | Harvest |
|---|---|---|---|
| 3a & 3b | Apr 4–Apr 11 | Jun 6–Jun 13 | Aug 30–Sep 6 |
| 4a & 4b (your zone) | Mar 20–Mar 27 | May 22–May 29 | Aug 15–Aug 22 |
| 5a & 5b | Mar 15–Mar 22 | May 17–May 24 | Aug 10–Aug 17 |
| 6a & 6b | Feb 28–Mar 7 | May 2–May 9 | Jul 26–Aug 2 |
| 7a & 7b | Feb 13–Feb 20 | Apr 17–Apr 24 | Jul 11–Jul 18 |
| 8a & 8b | Jan 28–Feb 4 | Apr 1–Apr 8 | Jun 25–Jul 2 |
| 9a & 9b | Dec 21–Dec 28 | Feb 22–Mar 1 | May 18–May 25 |
Harvest dates are about 85 days after the sow or plant-out date, not after starting seeds indoors.
Good companions
- Cabbage: Penn State Extension's herb-companion roundup lists hyssop as a traditional cole-crop companion, without describing a specific tested mechanism the way it does for basil/tomato or thyme/cole-crop pairings on the same page. Treat this as extension-repeated garden tradition, not a measured result.
Where to buy hyssop seeds
Botanical Interests · True Leaf Market (each supplier's hyssop seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing hyssop" 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 Hyssop in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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