Perennials 101, Perennials for Special Purposes
From patios and balconies to decks and porches, container gardens can add colour and interest to any area around your home… and you don’t even need a garden. There is a lot to consider in planting and maintaining container gardens, but these tips should provide enough information to make your first attempt a success.
Annuals make excellent long-flowering container specimens, however, perennials have one major advantage: although they do cost more initially, they can be placed out into your borders at the end of the season, gracing your garden for many years to come. Annuals, of course, require yearly replacement.
As more gardeners experiment with overwintering tubs and other containers with perennials in them, new information is becoming available on which plants will survive with minimal winter care, and which methods give the best results.
If you plan to try overwintering perennials in your pots, avoid clay (also called terra cotta) pots, since these can easily crack and break from the action of water expanding in the soil when it freezes. Gardeners in very mild winter regions have less of a problem with this.
The size of the pot makes a big difference to overwintering success. In Zones 1 through 7, pots should generally be at least 12 inches in diameter, and ideally over 16 inches. Those half whiskey barrels are an ideal size, but other large pots made of molded plastic (there are some GREAT plastic pots on the market now!), molded foam, concrete, wood or any other frost-proof material are worth considering. A depth of at least 12 inches is advised.
Starting with three basic plants is a good way to begin.
Since containers are meant to be focal points in the garden, this is a unique opportunity to be daring, and to use colors you might not ordinarily choose.
Our online Perennial Search Encyclopedia allows you to pull a list of perennials that are especially suitable for container gardening. Just search by Containers on the Attributes menu.
In contrast, alpine troughs (or other containers featuring rock garden plants) look best if the little mounding plants are placed with an inch or two of space in between. Try mulching the soil with a half inch of washed pea gravel, sand or small stones to give a finished look, and to prevent weeds or moss from flourishing.
Terra cotta (clay) and paper fiber containers dry out particularly quickly because they wick water out of the soil through the sides of the pot. Count on more frequent monitoring for these pots.
As a guideline, large containers in the sun require thorough watering twice a week, minimum. Containers planted with succulents or drought-tolerant alpines require less frequent watering and can endure several days without the hose.
Maintenance consists of removing faded flowers to promote re-bloom and pruning back leggy plants to keep them looking tidy and to encourage fresh, compact growth. Weeds should be removed as soon as they are noticed.
Successful wintering has much to do with your initial selection of plants. If you live in Zone 5, best results will be with perennials rated hardy in Zones 1 through 3, for instance. Growing plants rated two full zones colder than your region is wise, since the roots of plants in containers may experience more extremes of cold than those growing in your garden.
Some gardeners are also report good wintering results by simply leaving pots in a sheltered, shady spot outdoors… say, on the north side of the house. Bear in mind that winter winds may dry the soil out, so watering might be required during winter thaws. Use whatever extra snow is available, piling it over the pots for added insulation from the cold.
There is plenty of room for flights of fancy with container gardening. How about growing drought-resistant Hens and Chicks (Sempervivum) in old work boots filled with sandy soil? You could pose them permanently plodding up your steps!
There are numerous perennials, vines and shrubs which, in milder regions, remain attractive all winter. Consider planting Winter Heath (Erica carnea) with Bergenia, pansies, flowering kale and English Ivy (Hedera helix).
How about all-blue flowers and foliage? Try Serbian bellflower (Campanula poscharskyana) with blue fescue (Festuca glauca), English Lavender, Salvia ‘Blue Queen’ and dwarf Delphinium ‘Blue Mirror’.
Many varieties of succulent, drought-resistant perennials are available for this. A selection of colorful Sedums, Hens-and-Chicks, and Donkey-tail Spurge (Euphorbia myrsinites) can transform a large clay or concrete container into a spectacle of intriguing year-round color. Even better, succulent plants are generally tolerant of irregular watering.
There are so many kinds of creeping and cushion-forming alpines and rock garden plants suitable for container gardens. Concrete troughs are an excellent way to display these; you can build troughs yourself or purchase them all ready to be planted up.