Perennials in Containers
When the garden soil is so poor that it's nearly impossible to successfully grow plants in it, container plantings can be the solution. They can also be the answer for soil-less locations such as an apartment balcony, a deck, or a patio.
A third reason for raising container-grown perennials is to allow you to have those varieties that are not winter hardy in your climate. By growing them in containers, it's possible to easily move them into the house or a special shelter over the winter, then back into the garden in the spring.
Finally, it's sometimes nice to grow perennials, half hardy and half tender, as indoor plants, providing attractive displays within your home. After all, most houseplants are, in fact, perennials that are tropical and therefore not hardy for growing outdoors in most parts of the country. Some gardeners enjoy the novelty of growing various perennial bulbs in containers for winter bloom: tulips, daffodils, hyacinths, amaryllis, and lilies are popular choices.
Because of the extra care and space year-round container-grown plants require, you'll probably limit yourself to growing only those that are your special favorites -- perennials that look beautiful both while they're in bloom and when they are not and those that add appreciably to the decor of your home and garden.
To care for perennials in containers, follow the tips outlined for all container gardens, such as proper watering and drainage. In addition, repot plants when they show signs of becoming rootbound. An easy way to check is by knocking the plant out of the pot every six months to see how jammed with roots it has become -- when they're solidly matted, it's time to shift into a slightly larger pot, or to divide the plant into several pieces and repot.
To carry warm weather plants successfully through the winter in cold climates, it's necessary to bring them into the house or a greenhouse where warmth can be maintained. For those perennials that are half-hardy or require only slightly milder winters than those you have, it's possible to place them on an unheated enclosed porch or other similar location where daylight sun can reach them, but they're not subjected to extremely low temperatures. If sub-zero temperatures persist, a small space heater on a low setting will provide enough heat to prevent damage. Don't make it so warm that tender new growth is encouraged to sprout -- just fend off the very coldest conditions for the brief periods that they last.
Remember that potted plants overwintered under these conditions will require periodic watering in order to keep them from drying out. Such waterings should be infrequent as the plants metabolism is much slower in colder conditions.
Another way to display and group your plants is planting them in built-in raised beds. Learn about the usages for raised beds and some of the practicalities to consider in the next section.