Acanthus spinosus
Spiny bear’s breeches
a canthaceae
Spikes of mauve flowers;
shiny thistlelike leaves
3–4 ft. (2–2 1/2 ft.) high; 3 ft. wide
Part shade
Blooms June–July
Zones 5–10
pruning Deadheads remain attrac-
tive for several weeks after flowering is
finished. When they decline, cut to the
ground. If plants become tattered after
flowering in midsummer, they can be
deadleafed or, if severe, cut to the
ground for complete renewal of
foliage. No additional flowering will
occur. Foliage often remains healthy
until late summer (early September),
particularly if plants have received
sufficient summer moisture, at which
time the old declining foliage falls to
the outside of the plant, revealing
fresh, newly emerging basal growth.
Hedge shears can be used to quickly
remove the old leaves. The new growth
may remain evergreen or at least
semi-evergreen, depending on the
severity of the winter. Do not cut back
for the winter but cut off any damaged
leaves in the spring if needed. If plants
are grown for foliage alone, the flowerspikes can be easily pruned out when
in bud—plants will not flower if the
buds are removed.
other maintenance Although
generally listed as hardy in zones 7–10,
Acanthus spinosus has proved to be
reliably hardy in zone 5, though not
remaining as evergreen in bad winters.
Flowering is often reduced after cold
winters. Can be invasive in light soils,
and the spreading roots are difficult to
remove completely. Stays well
contained in clay soils and usually in
dry soils. Benefits from morning sun
and will take more sun and drier soilsA–Z Encyclopedia
of Perennials
Acanthus spinosus