Russian Sage
Russian sage, Perovskia atriplicifolia, is an attractive plant with
elongate, gray-green leaves and square, silvery-gray stems that produces an airy
cloud of color late in the summer. The tiny, purple-blue, tubular flowers are
arranged in whorls along long stems. This semi-woody plant was named Perennial
Plant of the Year in 1995 by the Perennial Plant Association. It superficially
resembles lavender, and can be used in areas too cold to grow lavender reliably.
This member of the mint family (Labiateae) is hardy in zones 4-9.
The
genus was named by the Russian botanist Karelin about 1840 after B. A. Perovski,
the Turkestani governor of the Russian
province of Orenburg
– but the plant is not native to Russia or a sage (Salvia). Perovskia
(pronounced "per-OFF-skee-uh") is native to Central Asia (Afghanistan, Pakistan,
etc.) and Tibet at elevations to
8,000 ft. The sage reference probably comes from the characteristic sage
aroma given off when the leaves are crushed. Russian sage has been in
cultivation since the mid-1800's.
Perovskia
can be used in the middle or back of the border or cottage garden or in many
other places in the landscape. It combines well with ornamental grasses and
white or yellow-flowered perennials, especially white phlox, Rudbeckia (blackeyed
Susan) and coreopsis. Other possible combinations include red-leaved barberry or
dark green foliage plants for contrast, or blending with other silver-leaved
plants. The silvery foliage and open architecture add an almost-Mediterranean
feel to the landscape, and can be useful as a filler plant. It is also useful
for separating stronger colors. Use it as a specimen in small areas, in mass to
intensify its presence in large spaces, or in a long, wide row as a divider
hedge.
Varieties
There
are seven species of Perovskia, but P. atriplicifolia is the only
one commonly available. [There is some confusion in the nursery trade, and
plants sold as this species may actually be a hybrid between P.
atriplicifolia and P. abrotanoides.] The species grows 3 to 4 feet
tall, producing lavender blue
flowers all summer on fine textured, aromatic, gray-green leaves and
gray-white stems. It is quite drought resistant. The flowers are attractive to
bees and other insects. Cultivars are generally superior to seed grown plants.
- 'Blue Haze' has paler blue flowers and nearly entire leaves (not finely
cut).
- 'Blue Spire' is an upright form with deeply lobed leaves. It reaches a height of 3
feet. The deep purple flowers are borne on larger panicles.
- 'Filigran' is an introduction from Germany's Ernst Pagels. This variety
has finer, more dissected foliage than the species, giving the plant an almost
lacy appearance. The bright blue flowers are borne all summer on upright 2-3
foot spikes.
- 'Little Spire' is more compact, growing only to about 2 feet tall.
- 'Longin' has stiff stems, for a more upright, formal growth habit.
Culture
Plant
Russian sage in full sun and well-drained soil, spacing the plants about 18
inches apart. Container-grown plants are best planted in early
spring, setting them at the same depth as they were in the
pot, but they can be planted out through the summer until one month before a hard killing frost.
Small plants may be slow to establish. Water regularly during the first growing season to establish a deep, extensive root
system. After the plants are established they can tolerate drought very well.
Once well-established, Russian sage is easy to grow, with essentially having
no disease or insect problems. The plants tend to flop a little, especially when young.
Russian sage can be staked, or planted near other plants that will support them.
Or, they can just be let go to provide a more informal look.
Good drainage and
aeration will enable the plant to survive wet winters. Plants will rot if the
soil is too moist. Leave the old stems on through winter and cut them down to
about a foot in the spring to keep the plants from getting woody (which can
result in a reduction in foliage and flower quality). Fertilize before new growth begins in spring.
Propagation
Russian sage can be grown from seed.
Sow seed at any time of the year, just covering the seed with medium.
Germination usually takes 1-4 months at a optimum temperature of 60-65ºF. An
initial cold treatment for 10 days to 6 weeks at 35-44ºF may enhance
germination, as well as produce a more compact plant. Transplant the seedlings
when they are large enough to handle, being careful not to damage the roots.
Harden off the seedlings before planting in the garden, preferably in late
spring.
To increase named varieties, taking 3-4 inch long softwood cuttings in summer
is the best method. Propagation by division is possible, but slow.
– Susan Mahr, Department of Horticulture, University of Wisconsin-Madison
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