SO YOU WANT TO GROW PERENNIALS
Extension Nursery and Greenhouse Crops Specialist
University of Vermont
Annuals are easy. You pick up a six-pack at your local
garden center and just pop them in the ground. No fuss,
no muss. Perennials require more decisions. That’s because
mistakes made with annuals are gone with the end of
the summer. Perennials will be in place for many years
When planting perennials, site selection, including
size and shape of the bed, is probably the most important
decision a gardener has to make. The bed should be located
where you can view–and enjoy–it from inside the house
or from a patio or deck. If your only option is a site
far away, then choose larger plants and strong colors
like reds and yellows rather than a lot of blues and
purples. The latter are fine if the bed is in your front
yard or close to the house.
When selecting a spot, check the background. Is it
pleasing? Or will you also be staring at a line of utility
poles and a dilapidated shed whenever you admire your
The size of the bed should be in proportion to the
rest of the garden. The shape should be pleasing to
the eye, even before the perennials are planted.
One common mistake gardeners make is in making the
beds too narrow. For beds viewed only from one side,
make the width at least the height of the tallest plant
if possible. If the bed will be viewed from two or more
sides, then the width of the bed should be at least
two times the height of the tallest plant. Long, narrow
beds usually work only if you are planting only one
variety such as day lilies.
When preparing the bed, don’t be overzealous with the
rototiller as this can break down the soil too much
and destroy the soil structure. Hand tilling is preferred.
However, you will need to dig down at least a foot or
more feet to loosen the soil.
Next, remove all weeds from the immediate area as these
can spread into perennial beds. If your soil is heavy
clay, add organic matter to lighten the soil and make
it easier to work.
When it’s time to select plants, be sure to choose
the right plants for the right site. Consider your soil
type and the amount of sun or shade a site will get.
Don’t think about flowers when you plan your perennial
garden. Most perennials are in bloom only a short time
each year, so consider foliage and forms of plants instead.
Don’t select only your favorite plants or lump them
all together in one space.
Contrast colors and form. Think in terms of combinations.
In other words, what will the flowers look good with,
not only other colors but textures. Consider ornamental
grasses for variety.
Although you’ll probably want to consult with a landscape
professional or garden center expert when planning your
perennial gardens, here are a few core plants to consider.
All have good shapes, attractive foliage all season,
and are hardy and fairly adaptable to most growing situations.
ASTERS–many cultivars are available from under
one foot in height (usually the New York asters) to
the four to five-foot tall New England asters; usually
blooms from mid September to mid October, depending
on cultivar; flower colors include reds, purples, pinks,
BAPTISIA–fairly rounded form, shrub-like, blue
flowers; blooms in June; doesn’t like to be moved once
GARDEN PHLOX–old-fashioned plant that blooms
in late summer; available in reds, whites, pinks, purples;
susceptible to powdery mildew, so try “David,”
a white phlox that is resistant to this disease and
grows to heights of four feet tall.
HOSTA–great for shade gardens; competes well
with tree roots; large variety of leaf shapes and sizes;
foliage colors range from blues, greens, and golds to
variegated; combines nicely with other plants; main
drawback is that slugs like them.
LIGULARIA–prefers semi-shade locations, morning
sun only; nice foliage plant with attractive yellow
blooms; flowers mid-summer. Keep well watered or in
moist soil as it wilts readily, but easily recovers.
PEONY–one of the best perennials; long-lived
(20+ years); attractive round blooms and foliage; blooms
in June; available in pinks, whites, and reds.
PERENNIAL GERANIUM (cranesbill)–excellent edging
plant to mid-border size; attractive aromatic foliage
and pink or purple blooms.
SIBERIAN IRIS–spiky purple or white flowers;
holds foliage nicely (unlike German irises); can stand
alone or in combination with other perennials such as
peonies; repetition in a bed is restful to the eye and
provides cohesion to the display; flowers in June; will
tolerate wet areas.
It usually takes three years for a perennial garden
to come into its own, depending on the size of the plants
initially planted, so be patient. During that time you
can adjust for mistakes. Don’t be afraid to borrow ideas
from others. And be sure to take time to enjoy your