Sunday, November 28, 2021

Notes from Greenwood Gardens 


In the Garden: Preparing Tender Garden Stars for Winter



As our 2021 season came to a close and the balmy autumn weather turned sharply colder, Greenwood Gardens’ horticulture staff began digging up our collection of tender perennials from garden beds and preparing them for winter storage. Gorgeous dahlias (above, left) dramatic colocasia (above, middle) and canna lilies (above, right) provided marvelous textures, colors, and magnificent foliage throughout the summer and early fall. But these sun and heat-loving garden stars cannot withstand the freezing temperatures of our northeastern winters. To preserve favorite specimens of these beautiful plants from one year to the next, they must be stored in a cool, indoor location until they can be replanted next year in late spring or early summer.
Plant enthusiasts and gardeners have been growing, saving, and sharing treasured dahlias and canna lilies for centuries. Canna lilies were imported from South American tropics to European gardens during the late 1500s and were all the rage during the Victorian era. They fell out of favor by 1930 when garden design aesthetics changed. The tall ornamental plants made a comeback during the 1990s when new cultivars captured gardeners’ imaginations.
Native to tropical climates of Mexico and Central America, dahlias were brought to cultivated gardens by the Aztecs, and imported to Europe in 1789 and the United States in the 1840s. Passion for these flowers has resulted in a vast variety of flower shapes from charming pom-pom dahlias the size of a golf ball to dinner-plate types with flower heads reaching eight to ten inches across.

The enormous leaves of colocasia plants gave rise to their colloquial name, “elephant ears.” The fascinating leaves of the species and newer cultivars like the ‘Teacup’ cultivar at right provide a dramatic focal point in ornamental gardens. Native to eastern Asia, the species Colocasia esculenta is an important food source known as taro and dahseen. It is so popular throughout Asian cultures that it is sometimes referred to as the “potato of the tropical world.”
These three tender perennials form three different types of underground, fleshy food-storage structures. Dahlias develop tubers, cannas make rhizomes (below) and colocasia grow corms. Home gardeners who wish to save or share favorite dahlias, canna lilies or colocasias can follow the same steps used by Greenwood’s horticulture staff, as outlined as follows by Sonia Uyterhoeven, Head of Horticulture:

  • Once the plants are removed from the soil, allow canna rhizomes and dahlia tubers to dry for a week in a frost-free location away from direct sunlight.
  • Remove any excess soil and inspect the rhizomes and tubers for rot. Cut dahlia and canna lily stems back to just one or two inches above the tubers and place them in a ventilated box with slightly moistened coir, peat moss, a vermiculite and perlite blend, or old newspaper. Place them in a cool, dry location where temperatures remain between 45- and 55 degrees F, such as a garage or basement.
  • Check dahlia tubers periodically throughout the winter. If the tubers appear dry and shriveled, spray lightly with water. If any start to rot, trim off the rotted portion of the clump so it won't spread.
  • Potted colocasia should be moved indoors before the danger of frost and can be grown as a houseplant in a cool, bright location. When kept at temperatures around 45-50F, they can be stored in low light since growth will be minimal. In temperatures above 50F, potted elephant ears will need more light since the plants will be actively growing. Since these plants are somewhat dormant, water them only if they begin to wilt.

Saving tender perennials from year to year is a centuries-old practice that has ensured the preservation of many treasured plants that continue to grace our gardens today.