Redbuds - The "Perfect" Tree

Our Plant of the Week on "Garden Talk" this week is the eastern redbud, Cercis canadensis. After discussing this tree with co-host Dr. Sue Hamilton, Nancy Schneider (woody plant specialist at Stanley's Greenhouse) and UT horticulture student David Pease, I have concluded it must be the "perfect" small tree for the Tennessee Valley region.

 

Besides welcoming spring with its display of pink blossoms, the eastern redbud offers the gardener many advantages. It grows easily in most soils. Because it is a legume, it actually helps to build the soil underneath it, by fixing atmospheric nitrogen with the help of bacteria living on the roots. Although tent caterpillars sometimes find the tree tasty, they are generally easy to control. The redbud has few other insect pests. Older trees are susceptible to trunk canker, a fungal disease that eventually kills the tree, although many specimens endure for a long time before succumbing to this problem. Otherwise, redbuds are carefree.

Transplant redbud trees from late fall until early spring. Container grown specimens typically bloom the year they are transplanted. Set the plants slightly higher than the surrounding soil, in order to avoid covering the crown. Water in and mulch. Irrigate if rainfall is insufficient. After the first season, the tree will be much more drought tolerant. Fertilization is not needed and may reduce bloom. Adaptable to many soil types, the redbud does best in well-drained, moisture retentive soil with organic matter.

Redbud trees grow easily from seeds, which are borne in pods that look like small snow peas. As a result, many cultivars and selections exist. Some of these are:

• 'Alba' -- a white-flowered form (f. alba) that comes true from seeds, sometimes incorrectly sold as 'Texas White"
• 'Dwarf White' -- another white-flowered redbud, it remains under 10 feet tall
• 'Forest Pansy' -- with new foliage that is deep burgundy red, this variety blooms later than the wild type
• 'Silver Cloud' -- white leaf variegation on a tree that prefers light shade
• 'Pink Heartbreaker' -- a weeping form that does not need staking to remain upright
• 'Covey' -- a dwarf weeping form that grows upright only if staked; unstaked plants will sprawl and become a ground cover

Besides our native eastern redbud, other species are sometimes available in garden centers. These include the western, or California, redbud (C. occidentalis) and the Chinese redbud (C. chinensis). The California redbud forms a multi-stemmed shrub when grown in the Tennessee Valley and is more sensitive to trunk canker than the eastern species. Chinese redbud is resistant to trunk canker, but grows much larger than the North American species, about 40 feet.

Flowers of the redbuds are edible. Native Americans used redbud for medicinal purposes. The flowers can be fried in batter, or mixed with nuts and honey or chopped dried fruit. Flower buds may be pickled like capers, and the green seed pods can be used much like snow peas in sautes and stir-fries. Honeybees and other pollinators are attracted to redbuds, and the eastern redbud is the host plant for Henry's elfin butterfly (Callophyrus henrici).

Holiday Gardening Gifts

In case you missed it this morning, I co-hosted "Garden Talk" on WNOX-FM 100.3 with Dr. Susan Hamilton of UT Gardens. I'll be filling in for Andy Pulte, the "Garden Guy," from now until January 12. Please join us and call in with your gardening questions!

Today's topic was "Plants To Give As Gifts." We focused on plants that look great this time of year, and that will be available in the local garden centers for gift giving. Because winter is the best time to transplant trees and shrubs, our discussion focused mostly on woody plants. But there's something for every garden in the list we made: big, little, slow-growing, fast-growing, shade and sun. The perfect plant for that special gardener in your life is out there waiting for a new home.


Here are some of our top choices:

• Winterberry holly, especially the cultivar 'Red Sprite' (pictured above)
• American holly, the traditional, slow-growing tree
• Yaupon holly, especially the dwarf, weeping cultivar introduced by Don Shadow
• Pyracantha
• False-cypress, many varieties to choose from
• Dwarf Alberta spruce
• Arborvitae, many varieties to choose from
• Virginia sweetspire, especially the cultivar 'Henry's Garnet'

We also suggested looking at the many planted containers offered by local garden centers such as Stanley's Greenhouses and Ellenburg Nursery. These usually feature dwarf evergreens, along with flowering annuals such as violas and pansies, that will last through the winter and in many cases can be planted out next spring.

We received a great question from a local caller: Which evergreens should I choose for fragrance? We seldom think about this aspect of the contribution that many conifers make to the garden, so it took both Sue and I a moment to come up with balsam fir, Abies balsamea. This tree is native to northeastern North America, from Newfoundland south to West Virginia. Further south, it is replaced in the mountains by Abies frasieri, Frasier's fir, a plant now threatened with extinction due to infestation by the balsam wooly adelgid. Balsam fir likes colder conditions that we typically experience in the Tennessee Valley, but may adapt if it receives some afternoon shade in the summer. A good substitute would be Korean fir, A. koreana. Much easier to grow, Colorado blue spruce, Picea pungens, received its botanical name due to its strong scent. The dwarf cultivar 'Baby Blue Eyes' remains small enough for most backyards.

If you do purchase trees and shrubs for holiday gifts, remember that these plants are accustomed to being outside in the cold at this time of year, and should not be brought indoors for more than 24 hours. Enjoy them during Christmas, then transplant them to the garden as soon as possible. Last year, we kept two evergreen trees on the front porch. We slipped the nursery containers inside two large decorative pots, and then trimmed the trees with lights. After New Year's we moved them to the garden, where they are thriving and look great against a backdrop of dark foliage from our Leyland cypress trees.

Please join us next week for another edition of "Garden Talk," Saturday, 8:00 AM, WNOX-FM 100.3