Monday, September 1, 2008

Patrick's Picks: Powell Gardens’ Flowering Trees

Gardeners first consider flowering tree varieties for their spring bloom display but have you thought about the shade potential in the average sized lot? Everybody would love to have a beautiful ‘Autumn Blaze’ Maple but 20 years later it can overwhelm even the average sized lot with a 50 foot tree. The biggest challenge for a gardener becomes the dense canopy which restricts your garden to the limits of dry shade plant options. The following varieties from Alan Branhagen of Powell Gardens can create a more graceful shade while providing spring and fall impact

Like myself, Alan hates to recommend brand new, untested trees or promote ones that are really hard to find! Here’s some new or underutilized trees generating the most comments at Powell Gardens that have thrived through the past decade of KC’s manic depressive weather of extreme heat, drought, flood, late freeze and arctic cold snaps:

Cherokee Brave Flowering Dogwood Cornus florida ‘Comco No. 1’
Many horticulturists have declared the flowering dogwood dead. They are falling over themselves trying to promote others while the dogwoods continue to defy their death sentence and outperform the newbies. The trademarked ‘Cherokee Brave’ Flowering Dogwood is a relatively new cultivar that has quickly gained popularity with proven disease resistance. The flower bracts emerge in mid-spring with an almost flat red color but quickly age to a coral pink and finally to a soft, apple blossom pink. This floral dance of butterflies (lasts 10 days on a warm, windy year as opposed to Amelanchier lasting one day) is always a knockout at Powell Gardens on “the first impression” curve of the Weir Memorial Dogwood walk just outside the Visitor Center. I always remind visitors to also take a whiff of the delightful heliotrope scent to the flowers! The foliage is mildew resistant (we rarely have conditions for dogwood anthracnose out here) and the trunks age to an interesting pebbled appearance. The 20 foot (tall and wide) tree has long-lasting red fall color and brilliant red berries for the birds in fall. The graceful, sympodial branching and the showy flower bud tipped twigs in winter complete the 4 seasons of ornamental interest. Plant dogwood in wind sheltered or woodland locations in rich, well-drained soil. Transplant balled and burlapped whenever possible (from trees dug in the spring).

Butterflies Magnolia Magnolia ‘Butterflies’ (hybrid origin)
There are too many awesome new hybrids of magnolia to mention and none have been trialed long enough to really get to know them. ‘Butterflies’ magnolia with its yellow, waterlily-like flowers before any leaves emerge is always a knockout at Powell Gardens. It blooms only for a short time in spring but it is a sight that attracts all visitors. Our tree grows on the east side of the Visitor Center trolley stop. The foliage is large and rich green all through summer and turns burnt gold and tan in the fall. The winter twigs are tipped with light gray furry buds for next spring’s bloom and the bark is smooth and light gray. The mature height of this tree will probably be around 30 feet with a narrower spread. Plant Butterflies Magnolia into rich, well-drained soil in full sun or part shade in a site where it will be shaded from morning sun or otherwise away from a frost pocket where a late frost won’t damage the flowers. Its only drawback is that small trees are shy to flower; it took our tree about 6 years to begin flowering en masse and it has done so every year since! It does not bloom as early as typical saucer magnolia so is less likely to suffer late frost damage (Powell Gardens’ tree has never had its flowers frozen – because I wrote this it will probably be doomed this spring!)

Fringetree Chionanthus virginicus
When the Missouri native Fringetrees bloom at Powell Gardens they get many questions and comments. This is really more of a large shrub but can keep slowly growing until small tree size in the 15-20ft. range of height and equal or greater spread. The pristine white flowers emerge after the main hurrah of spring as the new leaves emerge; and they act as lacey white flounces to the whorl of young leaves that crown over them. The flowers have a light, fresh fragrance. Trees are mainly male or female and female trees produce dark blue, olive-like fruit. The leaves are largish and relatively coarse but held in an informal pattern to fit in well with a woodland garden. Fall color is lemony to limey, yellow green, pleasant but not spectacular. Several fringetrees grace the Rock & Waterfall Garden where they have never failed to bloom. They thrive in well-drained soil and afternoon shade is best. We do have some in full sun in the parking lot to full shade under the canopy of native oak and hickory trees and all are doing well. This small flowering tree is a plant of Merit and promoted through Missouri’s Grow Native! program. This plants only pest for us is when stressed (just like its cousin the lilac) it is susceptible to the lilac-ash borer.

A big thanks to Alan for this detailed information and the exact locations to find specimens at Powell Gardens.

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