Although many gardeners assume that container plants should be cascading annuals, you also can “sweeten a pot” for perennials which normally wouldn’t thrive for you. If your soil is too heavy, wet, and/or acidic for Mediterranean plants such as lavenders, pinks, and thymes, try growing them in fast-draining containers filled with more appropriate sandy and alkaline potting soil.
You then can position the pots beside your porch steps or on a deck or patio, thus extending your gardening space and adding fragrance to your surroundings. Apartment dwellers without access to flowerbeds also may be able to raise—in more than one sense of the word! — perennials by placing them in containers on balconies or rooftops.
Since they can safely be left outdoors for longer than annuals can, hardy perennial plants will extend the container gardening season to run from spring through autumn. Perhaps even winter, if an evergreen perennial or two is included. Make sure, however, that you choose large containers which won’t crack, such as those constructed from wood, metal, or fiberglass rather than from ceramics or concrete.
Because plants in high places are more vulnerable to cold temperatures than those in the ground, potted perennials which will be left outdoors all year should be types which also would be hardy at least two zones north of where you live. If yours are more marginal than that, it’s a good idea to wheel the pots to a protected location inside an unheated garage or cold frame during winter.
For the best results, choose naturally compact plants whose foliage will be striking even when they aren’t in bloom. In a container to be placed in partial shade, for example, you might want to combine the dark frilly foliage of Heuchera ‘Plum Pudding’ with the contrasting silvery fronds of a Japanese painted fern and the golden oak-shaped leaves of the dwarf hydrangea ‘Little Honey'. For full sun, consider one of the low-growing and disease resistant Drift roses which should drift luxuriantly over a pot’s sides.
If you know you’ll need to move the containers later, position them atop heavy duty plant caddies before you fill them. And don’t forget to water them regularly or your perennials might go to pot in the more depressing way!
For more plant ideas on what to use for container gardening, click here!