Delphinium elatum
delphinium
ranunculaceaeBlue, purple, or white flower spikes;
palmately cut leaves
4–6 ft. high; 1–2 ft. wide
Full sun–part shade
Blooms June–July
Zones 3–7
pruning Deadhead to lateral flower
buds, if present; if not, cut off old
flowering spikes at a lateral leaf. After
all secondary flowering is completed
and the old stems start to decline, cut
back to newly developed basal foliage.
Plants will benefit from a topdressing
of compost and fertilizing with a
quick-release soluble fertilizer at this
time. Keep moist for sporadic smaller
and shorter rebloom later in the
season. When the young shoots are 6
in. tall, thin by approximately a third,
leaving at least 3–5 healthy stems per
mature clump, to avoid overcrowding
that increases susceptibility to disease.
Removing lateral flowering spikes mayincrease the size of the terminal flower.
Pinching to remove the large terminal
spike spoils the main effect of the
plant, although smaller side spikes
will still bloom. Remove any flowering
stalks for the winter, but leave the
basal foliage and cut back in the
spring.
other maintenance Delphinium
elatum is the true “maintenance
magnet.” It isn’t a beginner’s plant,
although it seems to be one of the first
perennials new gardeners are drawn
to, perhaps because of the glorious
pictures that appear in so many British
references. It does prosper in England,
due in part to the cool summers. This
delphinium is prone to a host of
diseases, which I won’t even go into,
and is a favorite food of slugs. It is also
subject to crown rot in poorly drained
soil and is short-lived. Carefully
dividing plants annually in the spring
may prolong life. Do not plant D.
elatum too deep. It will require staking,
and being a heavy feeder, it may need
additional fertilizer in spring or
summer. Many gardeners are better
off treating this one as an annual.
related plantS Delphinium
grandiflorum ‘Blue Butterflies’ grows
12–18 in. tall, with no staking needed.
Dwarf forms may not respond well to
pruning back after flowering. Do not
cut back unless basal growth is evident
and strong.
Delphinium ×belladonna ‘Bellamo-
sum’ (12–18 in.) generally isn’t as prone
to disease problems as D. elatum, and
thinning usually isn’t necessary in
more northern areas. Disbudding or
removing side flower spikes to
encourage a larger terminal flower is
not as applicable to this species as it is
to D. elatum, since a major appeal of
belladonna delphinium is its daintier
flowers.
Blackmore and Langdon strains of
delphinium tend to be more perennial
if divided regularly.
Connecticut Yankee Series, includ-
ing ‘Blue Fountains’, performs well in
heat. It grows to 2 ft. tall and is one of
the best performers in the Midwest.Delphinium elatum