Astilbe vs Siberian bugloss

Astilbe and Siberian bugloss are often considered for the same spot in the garden (flowers, ground cover). The data below shows where they differ: size, hardiness, care, toxicity and price.

Astilbe

Astilbe × arendsii 90 cm × 60 cm after 10 years

A splash of colour for shady, damp corners: feathery plumes in white, pink, red or purple rise above ferny foliage in early summer. Plant it only…

Perennial

Part shade

Shade

from about CZK 90

Siberian bugloss

Brunnera macrophylla 45 cm × 60 cm after 10 years

A shade-loving perennial with large, rough, heart-shaped leaves that carries a haze of tiny sky-blue, forget-me-not-like flowers above the foliage…

Perennial

Part shade

Shade

from about CZK 190

Key differences

Astilbe grows larger: 90 cm × 60 cm after ten years, against 45 cm × 60 cm for Siberian bugloss.
Siberian bugloss needs less water than Astilbe.
Siberian bugloss needs less care than Astilbe.
Astilbe is cheaper: about CZK 100 at the size usually planted, against about CZK 200 for Siberian bugloss.

Which one to choose?

Astilbe is the better choice if price matters.

Siberian bugloss is the better choice if space is tight, you cannot water regularly or you have little time for care.

Watch out for

Astilbe

Hot, dry Central European summers are the main problem: when the soil dries out the leaves brown and curl, and the clump weakens year after year. It will not survive in a sunny, dry bed without irrigation, and even in part or full shade it needs mulching and watering several times a week in drought. Powdery mildew, leaf spot and vine weevil occur occasionally.

Siberian bugloss

The leaves scorch and turn brown in hot sun and dry soil; in the hot, dry summers of Central Europe it looks tired by midsummer without shade and watering. Slugs and snails may chew the young shoots. It self-seeds where it is happy, and seedlings of variegated and silver cultivars mostly revert to plain green.

The data side by side

Feature	Astilbe	Siberian bugloss
Group	Perennial	Perennial
Size after 10 years	90 cm × 60 cm	45 cm × 60 cm
Ultimate size	0.4–1.4 m × 30–60 cm	30–45 cm × 45–75 cm
Growth rate	no data	Medium (uncertain)
Light	Part shade, Shade	Part shade, Shade
Soil	Average garden soil, Clay	Average garden soil, Clay
Hardiness	down to -34 °C (USDA 4, RHS H7)	down to -40 °C (USDA 3, RHS H7)
Heat tolerance	Low	Low
Foliage	Deciduous	Deciduous (uncertain)
Flowering	May–August, white, pink, red, purple	April–May, blue
Water need	High	Medium
Drought tolerance	Low	Low
Maintenance	Medium	Low
Planting distance	40 cm	40 cm
For dogs	no data	Non-toxic (uncertain)
For cats	Non-toxic (uncertain)	Non-toxic (uncertain)
For children	Non-toxic (uncertain)	Non-toxic (uncertain)
Typical price	approx. CZK 100	approx. CZK 200

Prices are rounded, indicative values. Toxicity data is for information only. If your pet or child has eaten a plant, contact a vet or a doctor. Data updated: October 17, 2026

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