Tuesday, April 30, 2019

American Yellowwood


May-June flowering tree
American yellowwood (Cladrastis kentukea), a member of the pea family (Fabaceae), is native to southeastern U.S. All other Cladrastis species are indigenous to Asia. Yellowwood is a beautiful medium-sized (35-45 feet) high tree with a broad crown, narrow profile, and upright branching.

Their pinnate compound leaves are alternately arranged. Each compound leaf is comprised 7-11 leaflets borne on a slender, green, 7-9 inches (20-30-cm) long rachis.

Dainty drooping panicles, almost wisteria-like, drip from the tips of branches in May or June, depending on regional location. The fragrant white-and-yellow pea-flowers are seldom borne on young trees and may take upwards of 10 years to bloom the first time. 
Yellowwood tends to be alternate-year bearing (i.e., bloom heavily one year, with little or no flowering the following year). Clusters of flattened green pea pods soon followed; each pod is 2-3 inch (10 cm) long and turns papery brown in autumn. Fall leaf color is brilliant yellow. The tree's light gray smooth bark, similar in appearance to beech (Fagus spp.), is an attractive four- season asset.

Yellowwood prefers a rich, deep, well-drained soil along with modest summer moisture. Leaves are subject to chlorosis (yellowing) in alkaline soils (pH above 7.2). This tap-rooted tree is drought tolerant within 2 years after planting. Yellowwood is not a good choice as a street tree as its surface roots may eventually push up sidewalks.

Narrow branch angles may result in limb trunked. When young, yellowwood needs to be correctively pruned to encourage wider branch angles and prevent bark inclusions. The cut branches tend to “bleed” sap excessively if pruned in winter.

Pests and diseases on yellowwood are rare, but the tree is susceptible to verticillium wilt. This thin bark tree is unfortunately subject to improper damage by line trimmers, mowers and other equipment, as well as sunscald over winter if young branches are left unshaded.

Sunday, April 14, 2019

Venus® Is A Unique Flowering Dogwood



7" Bracts of Venus® dogwood (C. kousa x C. nuttali)
Spring flowering dogwoods (Cornus spp.) are back in vogue again (USDA hardiness zones 6-9). A better understanding about growing dogwoods coupled with improved resistant disease varieties have seen the return of dogwoods to landscapes again.

If you want to plant a variety with the largest flowers, no question it is Venus®. This hybrid dogwood (Cornus kousa 'Chinensis' x Cornus nuttalii 'Goldspot' x Cornus kousa 'Rosea')  was developed at Rutgers University by Dr. Elwin R. Orton (now retired). The tree's large bracted blooms measure 6 - 7 inches across in April and May. 

Venus dogwood grows vigorously, 15-20 feet tall (slightly greater in spread). It is a small deciduous tree forms a dense, low-branched, spreading habit.

Venus is resistant to anthracnose and powdery mildew diseases. It has clean dark green foliage and large flowers. Red dogwood fruits attract lots of birds in early fall. Fall leaf color is red to orange.

This dogwood grows in average, medium moisture, well-drained soils in full sun to partial shade. In southeastern U.S., morning sunlight and afternoon shade is best. Summer leaf scorch may indicate too much direct sunlight and/or exposure to hot, windy or dry soil conditions. The tree benefits by applying 2-3 inches of a wood-based or needle mulch that keeps tree roots cool and moist. For the first 2-3 summers, a young dogwood should be irrigated during dry periods.

Venus dogwood, when properly sited and cared for, have few disease and insect problems. Stressed trees become vulnerable to stem cankers and insect borers. Deer are usually not troublesome.

Dogwoods are planted on urban and suburban lawns and around patio areas. Venus dogwood needs to be special ordered from garden centers or purchase from e-commerce nursery sources.

Monday, April 1, 2019

Baptisias

'Purple Smoke' baptisia
Baptisia (Baptisia spp.) are beautiful long-lived low maintenance native perennials. Plants thrive in rich well-drained soil under plenty of sunlight. When planting, treat the roots as fragile and permit baptisia one year to establish itself. They will reward you with many years of spring flowering.

False blue indigo (Baptisia australis) was selected Perennial Plant Of The Year in 2010 by the Perennial Plant Association.  Most modern day cultivars are usually hybrids. Lovely spikes of purple (B. australis), lavender blue (B. minor), white (B. alba), bright yellow (B. sphaerocarpa) and bicolors appear in May (in Tennessee). Each species or cultivar blooms for 2-3 weeks.  Bloom stalks can be included in fresh flower arrangements

Plants grown in partial shade may appear stretched or leggy, requiring some staking. Fewer flower spikes are produced in shady places. I opt to remove the pea -like pods that form within a month after flowering because the weighty pods may detract from its shrub-like appearance. Plants are cut down to the ground in late fall and added to the compost bin.

Blue false indigo is a beautiful, long-lived, drought tolerant perennial with a robust habit and attractive steel blue-gray foliage. In late May, its intensely saturated violet-blue flower spikes rise above 3-4 feet tall multi-stemmed plants with bluish-green foliage.

Baptisias are at their best in full sun and in moist, well-drained soils. Fertilize sparingly to avoid the plant from flopping.  If grown in full sun, you do not need to stake baptisia. Baptisia is heat and drought tolerant and rarely troubled by diseases and insects.

The single plant spreads slowly by rhizomes and eventually will crowd out neighboring plants. Divide clumps every 5 -7 years and share divisions with your gardening friends or start new plantings.