other maintenance Four key
things to remember for best results
with Astilbe plants are: (1) they are
heavy feeders; (2) summer drought is
their worst enemy—keep watered in
July and August; (3) winter wetness is
their next worst enemy; (4) and they
should be divided every 3 years to
maintain vigor. Astilbe needs
high-nitrogen fertilization in the
spring or autumn, either from
composted manures or fertilizers or
both. Dave Beattie, renowned astilbe
grower, recommends using a
general-purpose lawn fertilizer, such
as a 20–10–10, in early October for best
results. The overwintering structure of
the plant increases in size in Novem-
ber, just before the last hard frost, so
an October application of fertilizer will
help its development. Also, early
flowering astilbe form buds in the
autumn for next year’s flowers. All
late-flowering A. chinensis types, such
as A. chinensis ‘Pumila’, are moretolerant of dry conditions; others
should be kept moist during the
summer. Astilbe plants will tolerate
full sun if given plenty of moisture. In
zones 3, 4, or 5, spring planting, or
planting no later than September 1, is
advisable or plants may heave,
especially smaller-growing forms such
as A. simplicifolia ‘William Buchanan’.
If crowns rise above the soil, gently
press in, and top-dress with organic
matter. Divide in the early spring or
midsummer before September.
related plantS Astilbe ×arendsii
‘Hyazinth’ is a sturdy-stemmed,
abundantly flowered cultivar, with
lavender-pink blooms that fade
to white.
Astilbe biternata (false goatsbeard) is
the only astilbe native to North America,
and has long been underutilized. It is a
bold plant, 3–6 ft. tall with feathery
white panicles set above a 3-lobed
terminal leaflet. Deadleafing is required
midsummer for best appearance.Astrantia major