Astilbe in Zone 5a & 5b

Astilbe x arendsii

When to plant astilbe in zone 5b

Zones 5a and 5b share the same average frost dates in our data, so this page covers both.

Method: Direct sow: Direct-sow outside. Astilbe doesn't transplant well, or doesn't need the extra time indoors.

Start indoors	Not typically started indoors
Direct sow / transplant outside	Apr 26–May 3
Estimated bloom	Apr 25 '28–May 2 '28 (First real harvest the season after planting)

Spacing: about 2 square feet per plant (square-foot-gardening spacing). Mature height: 1.5-4.5 ft.

Astilbe gives feathery plumes in shade, which is a rare combination. It asks for one thing in return and it does not negotiate.

How astilbe fits zone 5's season

Zone 5b's frost-free window runs about 148 days, from May 10 to October 5. Astilbe takes about 1 growing season to reach full flowering, so what matters here is how many of these seasons it gets, not whether one is long enough.

Astilbe is hardy in zones 3-9, so in zone 5b it stays in the ground through winter and comes back rather than being replanted. Allow about 1.5 ft of spread at maturity.

Good companions

No standout companions recorded yet for Astilbe.

Where to buy astilbe seeds

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