Forget the garden cops and put your perennials in pots

Last Modified: Friday, November 7, 2003 at 8:11 p.m.

Rules are meant to be broken. And nowhere in horticulture is it more appropriate to do just that than planting perennials in pots.


`Galaxy Hybrids' Yarrow

Until fairly recently, it simply wasn't done, at least not in USDA Zone 5b. The reasoning was both logical and persuasive: Most perennials bloomed for too short a period - just two to three weeks on average - to make effective patio plants. Besides that, their roots wouldn't survive winters in containers, requiring gardeners to replant every spring.

In a rather gutsy move, some gardener somewhere decided to ignore conventional wisdom and plant a perennial in a pot. The horticultural police were summoned, but because they could find no ordinance against it no citation could be issued.

Thus tested, accepted practices collapsed and gardeners rushed to replace ho-hum geraniums and boring begonias with "exotic" perennials.

Meanwhile, perennials themselves were becoming more attractive as container plants. Many new varieties bloomed for a long period of time. And purveyors of perennials were successfully "selling" gardeners on the virtues of beautiful foliage and interesting textures.

This fusion of ideas and innovation - pots made of materials that were reliably winter-proof helped, too - created an "anything goes" attitude that invited experimentation. The result is wonderful container gardens that mix perennials, herbs, annuals, vines and groundcovers in combinations as unique as the gardeners who plant them.

"Best" perennials for containers are whatever strikes your fancy, but if you want to try overwintering them in their pots, choose those with the hardiest roots. Yarrow (Achillea) is tough, and it comes in a variety of heights and colors. Blanket flower (Gaillardia), sedum, and black-eyed Susan (Rudbeckia) all have sturdy roots.

It's hard to kill daylilies, and excellent new cultivars of goldenrod (Solidago) and purple coneflower (Echinacea) are certainly used to the rigors of brutal Midwestern winters.

To overwinter perennials in containers, cut the foliage back in autumn as you normally would each plant and group the pots together, sides touching, in a protected, but cold, place. An unheated porch or garage is ideal, but a spot next to the house will do, as long as it's out of the wind.

Alternately, some gardeners bury their pots in a cold frame or in the ground, or they build an enclosure and stuff it with Styrofoam peanuts or straw.

Don't shower perennials with tender loving care and move them into a snug root cellar or cool sunroom. They want to - need to - go dormant for the winter months.

Once the pots are in place, cover the soil with two inches of mulch. Double wrap the pots with insulating bubble wrap or foam sheeting (available through greenhouse supply catalogs) and toss a burlap blanket over all.

You may lose a few plants this way, but most perennials will make it through the winter in they're "tucked in" as described.

If all that sounds like too much trouble - it's really not, especially if you save the wrap from year to year - there are dozens of perennials that will deliver their money's worth if grown just for one season. For a start, select varieties with gorgeous foliage, such as artemisia, giant bugle weed (Ajuga reptans 'Caitlin's Giant'), multi-colored hostas, heuchera and bergenia.

Perennials with a long bloom period are especially valuable for their color: Corydalis lutea, coreopsis ('Moonbeam', 'Limerock Beauty' and 'Sweet Dreams' are excellent), Russian sage, Gaura lindheimeri and catmint. Repeat bloomers (cut plants back after the first blush of bloom to encourage an encore) include beebalm, salvia, daisies and false sunflower.

Exquisite texture is the most elegant quality of all. Wonderful textures can be found in ornamental grasses such as fountain grass (Pennisetum) and golden variegated Japanese forest grass (Hakonechloa), as well as in feathery plants like fernleaf peony, Amsonia heubrechtii and dwarf baby's breath.

And don't forget the allure of perennial herbs, whose fragrance, color, texture, and usefulness make them favorite container specimens all by themselves or mixed with annuals. Chives, thyme, mint, lavender, oregano, sage and tarragon are all perennial herbs.

Care for container perennials as you would if they were growing in the landscape: Divide fast-growing varieties often, or they'll become crowded and start to decline. Deadhead regularly to maintain a tidy, well-groomed appearance, and stake taller varieties to keep stems from flopping.

On difference you'll notice is that perennials in pots require more water and fertilizer than their in-ground counterparts. Meet these cultural needs and your perennials will share space on your patio for many seasons.

Lindsay Bond Totten, a horticulturist, writes about gardening for Scripps Howard News Service.


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