Preserving Your Container Plants
Fall is upon us! Frost will soon sweep its deadly, icy grip across our beloved plants that we’ve cultivated and nurtured this season. Container plants, in particular, can be a challenge to preserve if they incorporate not just annuals, but showy tropicals, perennials, and hardy woody plants as well. What does one do with a mixed container during the winter? No worries! There are many techniques for saving annual, perennial, tropical, and dry-loving container plants that will preserve them for seasons to come.
Preservation techniques will vary depending on the plants in your container. Tropical plants can be over-wintered using methods replicating a dry season, forcing the plant into dormancy; hardy perennials and woody shrubs need a cold dormancy to grow in the spring, so they must stay outside; cacti and succulents prefer their winters warm and dry and must be brought inside; while many annuals can be propagated by stem cuttings or just re-potted and maintained inside.
A lot of bulbous/tuberous tropical plants have a natural dry season (analogous to our winter) when their leafy parts die off, leaving the bulb behind. Don’t throw them away! After heavy frosts turn the above ground plant parts to mush, cut the damaged foliage off about four inches above the thickened bulb. Then, dig them up and remove all excess soil from the roots.
At this point, you can determine if the clump needs dividing. If it needs dividing, be sure to dust all cut surfaces with a sulfur-based fungicide made for bulbs to prevent the wounds from rotting. Cut the roots back to one inch from the bulb and leave it to dry out evenly. Rotten bulbs/roots need to be thrown away so infection doesn’t spread to healthy bulbs.
Sitting on something absorbent like newspaper, a bulb/tuber’s drying time can last up to two weeks if located somewhere shaded and dry such as a garage or basement. Once clean and dry, bulbs should be stored preferably around 50° F all winter in damp (not soggy) milled peat moss. This prevents the bulbs from drying out any further, which could cause them to die. Many gardeners don’t have a perfectly cool basement or garage to keep bulbs dormant. Alternative methods for dry storage include a dark closet with the door cracked for circulation, a cabinet, or underneath a bed in a cardboard box punched with a few holes also for airflow. The important thing to keep in mind is that the bulb needs to be kept on the dry side, in the dark, and moderately warm.
If the bulbs were grown as a single specimen in their own pot, the entire pot can be placed in a garage which stays above 50° F or a cool basement and allowed to dry out completely. Cut all above ground plant parts flush with the soil and don’t water until outside temperatures stabilize above 60° F. Often, bulbs break dormancy unexpectedly in this dry pot method. If this happens, pots can be moved to a sunny location near a window and watered sparingly until they can be placed outside. The emerging leaves will be stunted, but once outside, the plant will replace any spindly leaves with lush, new ones.
Tropical Vines, Shrubs, and Trees
Dig the desired plant out of its summer home and place in a pot with highly milled peat moss. Most tropical plants benefit from having some sunlight in the winter, so choose an area for the tropical that has a moderate amount of light such as a living room corner or heated garage.
Additionally, keeping the plants on the dry side helps to reduce growth and preserve dormancy until temperatures stabilize at about 60° F. Curtail any fertilizing until spring to inhibit active growth. Plants may lose most or all of their leaves, but as long as the stems stay green and pliable, the plants should be fine for spring planting. Minimal conditions keep the plants alive but discourage active growth. When outside temperatures stabilize in the 60’s, plants can be brought outside. To avoid foliage burn, keep them in a shady area until they’ve adjusted to increased sun exposure.
Otherwise, the plants can be cut back by half, potted in a peat-based soil-less mix, and placed on a sunny windowsill. With a wide assortment of “annuals” available in the market, some research is required to determine which annuals can be over wintered successfully. True annuals (e.g., basils, cockscomb, zinnias, etc.)—regardless of any treatment given—will go to seed and die when brought inside.
As with other tropical plants, succulents also need time to adjust to sunnier conditions in the spring. Move them to a shady spot outside when temperatures have stabilized above 60° F and then gradually introduce them to brighter conditions.
If the container has to be removed, hardy perennials and woody shrubs can be temporarily planted in the ground and mulched. Dig them from the garden in the spring, if you wish, and replant into a container. Or, leave them in their garden spot and start over with fresh ideas and new plant material.
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Last Updated October 23, 2006 2:04 PM
URL = http://www.usna.usda.gov/Gardens/faqs/containerpreserve.html