Butterfly Weed (Asclepias) in Zone 3a & 3b
Asclepias tuberosa
Yes, butterfly weed (asclepias) grows in zones 3a and 3b. Start seeds indoors Apr 4–Apr 11 and plant out Jun 6–Jun 13.
When to plant butterfly weed (asclepias) in zone 3b
Zones 3a and 3b 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 | Apr 4–Apr 11 |
|---|---|
| Direct sow / transplant outside | Jun 6–Jun 13 |
| Estimated bloom | About a year after planting |
Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1.5-3 ft.
Plant alongside it in zone 3b
These go outside within two weeks of butterfly weed (asclepias) in zone 3b, so one planting day can cover them.
- NasturtiumJun 6–Jun 13
- MarigoldJun 6–Jun 13
- Ageratum (Flossflower)Jun 6–Jun 13
- Annual Geranium (Pelargonium)Jun 6–Jun 13
- Campanula (Bellflower)Jun 6–Jun 13
- Castor BeanJun 6–Jun 13
Butterfly weed is a native perennial wildflower grown as much for feeding monarch butterfly caterpillars, one of the milkweeds they depend on, as for its own clusters of bright orange flowers.
How butterfly weed (asclepias) fits zone 3's season
Zone 3b's frost-free window runs about 98 days, from May 30 to September 5. Butterfly weed (asclepias) takes about a year from planting to first bloom, so it spans more than one growing season.
Butterfly Weed (Asclepias) planting windows in every zone
Zone 3b 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 (your zone) | Apr 4–Apr 11 | Jun 6–Jun 13 | About a year after planting |
| 4a & 4b | Mar 20–Mar 27 | May 22–May 29 | About a year after planting |
| 5a & 5b | Mar 15–Mar 22 | May 17–May 24 | About a year after planting |
| 6a & 6b | Feb 28–Mar 7 | May 2–May 9 | About a year after planting |
| 7a & 7b | Feb 13–Feb 20 | Apr 17–Apr 24 | About a year after planting |
| 8a & 8b | Jan 28–Feb 4 | Apr 1–Apr 8 | About a year after planting |
| 9a & 9b | Dec 21–Dec 28 | Feb 22–Mar 1 | About a year after planting |
Good companions
No well-established companions for butterfly weed (asclepias).
Where to buy butterfly weed seeds
None of the seed suppliers we list carries butterfly weed seeds right now. A local garden center or a specialty seed house is the place to look.
See why we recommend these suppliers →
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See it growing
Search YouTube for "growing butterfly weed (asclepias)" videos → (a live search, not a hand-picked video; results vary and aren't vetted by us)
← Back to the full zone 3b calendar · Plan your beds in the Garden Designer →
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Growing Butterfly Weed (Asclepias) in USDA zone 3b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.
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