Butterfly Weed (Asclepias) in Zone 4a & 4b

Asclepias tuberosa

When to plant butterfly weed (asclepias) in zone 4b

Zones 4a and 4b share the same average frost dates in our data, so this page covers both.

Method: Start indoors: Start indoors from seed, then transplant outside. Butterfly Weed (Asclepias) needs a head start most zones can't give it by direct-sowing alone.

Spacing: 1 per square foot (square-foot-gardening spacing). Mature height: 1.5-3 ft.

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 4's season

Zone 4b's frost-free window runs about 128 days, from May 15 to September 20. Butterfly Weed (Asclepias) needs about 365 days from transplant to first harvest.

Good companions

No standout companions recorded yet for Butterfly Weed (Asclepias).

Where to buy butterfly weed seeds

• Botanical Interests
• True Leaf Market
• Burpee
• High Mowing Organic Seeds

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 4b calendar · Full companion planting guide · Full plant profile · Plan your beds in the Garden Designer →

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Growing Butterfly Weed (Asclepias) in USDA zone 4b: when to start seeds indoors, when to direct-sow, and when to expect a bloom.

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