By Dr. Leonard Perry 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 to come.
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 flowers?
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, and white.
BAPTISIA–fairly rounded form, shrub-like, blue flowers; blooms in June; doesn’t like to be moved once planted.
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 new garden!