Foxglove in Zone 4a & 4b
Digitalis purpurea
Yes, foxglove grows in zones 4a and 4b. Start seeds indoors Feb 27–Mar 6 and plant out May 22–May 29.
When to plant foxglove 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 | Feb 27–Mar 6 |
|---|---|
| Direct sow / transplant outside | May 22–May 29 |
| Estimated bloom | About a year after planting |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 2-5 ft.
Plant alongside it in zone 4b
These go outside within two weeks of foxglove in zone 4b, so one planting day can cover them.
- NasturtiumMay 22–May 29
- MarigoldMay 22–May 29
- Ageratum (Flossflower)May 22–May 29
- Annual Geranium (Pelargonium)May 22–May 29
- Butterfly Weed (Asclepias)May 22–May 29
- Campanula (Bellflower)May 22–May 29
Foxglove produces some of the most dramatic flower spikes of any garden biennial, tall stalks lined with tubular, often speckled blooms. It's also the source of digoxin, a real heart medication, which is a way of saying every part of this plant is toxic if eaten, not just mildly irritating.
How foxglove fits zone 4's season
Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Foxglove takes about a year from planting to first bloom, so it spans more than one growing season.
Foxglove 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 |
|---|---|---|---|
| 4a & 4b (your zone) | Feb 27–Mar 6 | May 22–May 29 | About a year after planting |
| 5a & 5b | Feb 22–Mar 1 | May 17–May 24 | About a year after planting |
| 6a & 6b | Feb 7–Feb 14 | May 2–May 9 | About a year after planting |
| 7a & 7b | Jan 23–Jan 30 | Apr 17–Apr 24 | About a year after planting |
| 8a & 8b | Jan 7–Jan 14 | Apr 1–Apr 8 | About a year after planting |
Good companions
No well-established companions for foxglove.
Where to buy foxglove seeds
Burpee (each supplier's foxglove seeds)
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing foxglove" 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 Foxglove in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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