Milk Thistle in Zone 7a & 7b
Silybum marianum
Yes, milk thistle grows in zones 7a and 7b. Plant it outside Mar 27–Apr 3.
When to plant milk thistle in zone 7b
Zones 7a and 7b 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 | Mar 27–Apr 3 |
| Estimated harvest | Jul 25–Aug 1 (~120 days after direct-sowing) |
Spacing: about 4 square feet per plant (square-foot-gardening spacing). Mature height: 3-5 ft.
Plant alongside it in zone 7b
These go outside within two weeks of milk thistle in zone 7b, so one planting day can cover them.
- DillApr 3–Apr 10
- BorageApr 10–Apr 17
- ChervilMar 27–Apr 3
- ChivesMar 27–Apr 3
- HorehoundMar 27–Apr 3
- ParsleyMar 27–Apr 3
Milk thistle is handsome, widely sold as a medicinal herb, and illegal to let grow in parts of the country.
How milk thistle fits zone 7's season
Zone 7b's frost-free window runs about 198 days, from April 10 to October 25. Milk thistle needs about 120 days from sowing to first harvest.
Milk Thistle planting windows in every zone
Zone 7b is highlighted. Useful for comparing against a neighbouring zone, or for a garden somewhere else.
| Zone | Start indoors | Sow or plant out | Harvest |
|---|---|---|---|
| 5a & 5b | Not usually | Apr 26–May 3 | Aug 24–Aug 31 |
| 6a & 6b | Not usually | Apr 11–Apr 18 | Aug 9–Aug 16 |
| 7a & 7b (your zone) | Not usually | Mar 27–Apr 3 | Jul 25–Aug 1 |
| 8a & 8b | Not usually | Mar 11–Mar 18 | Jul 9–Jul 16 |
| 9a & 9b | Not usually | Feb 1–Feb 8 | Jun 1–Jun 8 |
| 10a & 10b | Not usually | Jan 16–Jan 23 | May 16–May 23 |
Harvest dates are about 120 days after the sow or plant-out date.
Good companions
No well-established companions for milk thistle.
Where to buy milk thistle seeds
True Leaf Market (each supplier's milk thistle seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing milk thistle" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 7b calendar · Plan your beds in the Garden Designer →
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Growing Milk Thistle in USDA zone 7b: when to start seeds indoors, when to direct-sow, and when to expect a harvest.
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