Thyme in Zone 4a & 4b
Thymus vulgaris
Yes, thyme grows in zones 4a and 4b. Start seeds indoors Mar 20–Mar 27 and plant out May 22–May 29.
When to plant thyme in zone 4b
Zones 4a and 4b share the same average frost dates, so this page covers both.
Method: Start indoors: Start indoors from seed, then transplant outside. It needs a head start most zones can't give it by direct-sowing alone.
| Start indoors | Mar 20–Mar 27 |
|---|---|
| Direct sow / transplant outside | May 22–May 29 |
| Estimated harvest | Aug 20–Aug 27 (~90 days after transplanting) |
Spacing: 4 per square foot (square-foot-gardening spacing). Mature height: 0.5-1 ft.
Plant alongside it in zone 4b
These go outside within two weeks of thyme 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
Thyme is a low, spreading perennial, not an annual herb you replant each spring. Once established, it comes back reliably year after year and slowly fills in as a groundcover.
How thyme fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Thyme needs about 90 days from transplant to first harvest.
Thyme 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 |
|---|---|---|---|
| 4a & 4b (your zone) | Mar 20–Mar 27 | May 22–May 29 | Aug 20–Aug 27 |
| 5a & 5b | Mar 15–Mar 22 | May 17–May 24 | Aug 15–Aug 22 |
| 6a & 6b | Feb 28–Mar 7 | May 2–May 9 | Jul 31–Aug 7 |
| 7a & 7b | Feb 13–Feb 20 | Apr 17–Apr 24 | Jul 16–Jul 23 |
| 8a & 8b | Jan 28–Feb 4 | Apr 1–Apr 8 | Jun 30–Jul 7 |
| 9a & 9b | Dec 21–Dec 28 | Feb 22–Mar 1 | May 23–May 30 |
| 10a & 10bSpring window | Not usually | Feb–Apr | ~90 days after transplanting |
| Fall window | Not usually | Oct–Nov | ~90 days after transplanting |
| 11a & 11b | Nov 6–Nov 13 | Jan 8–Jan 15 | Apr 8–Apr 15 |
Harvest dates are about 90 days after the sow or plant-out date, not after starting seeds indoors.
Good companions
- Cabbage: Penn State Extension lists thyme among the herbs that measurably deter cabbage loopers on brassicas, the same protective role sage and dill play.
Where to buy thyme seeds
True Leaf Market · Burpee · High Mowing Organic Seeds (each supplier's thyme seeds)
Varieties we recommend, and where to get them:
- French or English Thyme: Illinois Extension calls French and English thyme the most popular of the culinary types, distinguishing them from ornamental types like woolly thyme that are grown for rock gardens rather than the kitchen. Buy: Botanical Interests · True Leaf Market Full notes
- Creeping thyme (Thymus serpyllum) (best for groundcover, pathways, not cooking): NC State Extension notes this at just 2-3 inches tall spreading 3-12 inches wide, with deep pink to purple flowers, grown as an ornamental groundcover for pathways and rock gardens rather than for the kitchen the way French or English thyme is. Buy: Botanical Interests · True Leaf Market · Burpee Full notes
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing thyme" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
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Growing Thyme in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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