Ageratina havanensis
shrubby boneset
Overview
Ageratina havanensis is a deciduous to semi-evergreen shrub in the aster family that grows 2–6 feet (0.6–1.8 m) tall and wide, with slender, brittle, much-branched stems. The leaves are triangular to heart-shaped, 1–2.5 inches (2.5–6 cm) long, with toothed margins, arranged opposite along the stems. From September to November the plant is covered in rounded clusters of small, fluffy flower heads that lack ray petals, ranging from white to pink, and carrying a sweet scent. The flowers draw large numbers of butterflies, bees, and other pollinators during autumn migration. Each head produces small dry seeds tipped with white pappus that disperse on wind. Ageratina havanensis grows on dry limestone slopes, canyon edges, and rocky outcrops in central and western Texas and into Mexico. It tolerates heat, drought, and shallow alkaline soils once established, and resprouts after a hard freeze cuts back the top. The brittle stems break easily, and the shrub can look open and twiggy outside the brief autumn bloom. It does not grow well in wet, heavy, or poorly drained soils.
Native Range
Native to central and western Texas and northeastern Mexico, growing on dry limestone slopes, canyon rims, rocky outcrops, and the edges of woodland. It is adapted to shallow, alkaline, well-drained soils.Suggested Uses
Ageratina havanensis is used in butterfly and pollinator gardens, native shrub borders, and dry, rocky landscapes in its native region. Its autumn flowers draw migrating butterflies, and the shrub suits naturalized plantings on limestone soils. It works as a filler among other drought-tolerant shrubs where its brief bloom adds late-season color.How to Identify
Appearance
Size & Dimensions
Height2' - 6'
Width/Spread2' - 5'
Bloom Information
Fluffy white-to-pink flower clusters open from September to November, peaking in October. The scented heads draw migrating butterflies and other pollinators over several weeks. Wind-borne seeds with white pappus follow as the heads dry.
Detailed Descriptions
Flower Description
white to pinkFoliage Description
greenGrowing Conditions
Sun Requirements
Requires 6-12 hours of direct sunlight daily
• Full Sun: 6+ hours of direct sunlight
• Partial Shade: 3-6 hours of direct sunlight
• Full Shade: Less than 3 hours of direct sunlight
Care & Maintenance
Care Guide
Ageratina havanensis grows in full sun to part shade on dry, well-drained, rocky or alkaline soils and tolerates limestone and shallow ground. It needs little water once established and withstands heat and drought. The plant can be cut back hard in late winter to renew its shape, since it blooms on new growth and resprouts after frost kills the top. It grows from seed or softwood cuttings. It does not grow well in wet or heavy soils, which cause root problems. Flowering is heaviest in full sun.Pruning
Ageratina havanensis can be cut back by a third to a half in late winter to keep a denser shape, because it flowers on the current season''s growth. Dead or broken stems can be removed at any time. The shrub resprouts from the base after a hard freeze.Pruning Schedule
J
F
M
A
M
J
J
A
S
O
N
D
winter
Container Growing
✓ Suitable for container growing
Minimum container size: 5 gallons