July/August Blooming Plumleaf Azaleas

July/August Blooming Plumleaf Azalea

Plumleaf azalea (Rhododendron prunifolium) is a deciduous azalea that is native to  Georgia and Alabama mountains (USDA hardiness zones 6-9). It is one of the signature plants of Callaway Gardens in Pine Mountain, Georgia.

Their bright orange-red flowers surprise in late July into early Augusta and may last for 2 weeks or more. Compared to many other spring blooming native azaleas, flowers are not fragrant. Spring and summer foliage is medium-green and is mostly blemish-free.

Fall leaf color is also uneventful. Insect and disease problems are rare if the plant is properly sited. 

This 5-8 feet tall and wide shrub performs best in morning sunlight and shaded from the harsh afternoon summer sun. It thrives in well-drained, compost amended soil. Plumleaf azalea prospers in the calcareous clay soils found in the Appalachian region without pH correction.  Plant in full-day light shade in zones 7-9. Set the shrub into a shallow wide dug hole that has been generously amended with compost and/or peat.

Feed in early spring with a slow-release fertilizer such as Osmocote™ or Nutricote™. An alternative nutrition program is to use a water soluble product such as Miracle-Gro™ or Jack's™  in early spring and again in early summer. Maintain 2-3 inches of a pine-based mulch around the base of the shrub. Irrigate plant(s) the first 2 years of establishment.

Plumleaf azalea blooms on new current season's wood. Prune deciduous azaleas anytime after bloom to maintain a desired height and spread. Plumleaf azalea is primarily available at local native plant nurseries or is offered online.

Plumleaf azaleas are usually available from mail order companies on-line.

Hardier And More Colorful Hydrangeas

Summer Crush™ hydrangea

For over a quarter of a century, hydrangea breeders (Bailey's, Spring Meadows, and other nurseries) have introduced hardier, tougher, and more colorful bigleaf hydrangeas (Hydrangea macrophylla) that bloom on both new and old wood (USDA hardiness zones 5-8). 

Old wood flowers are set on last year’s growth and new wood flowers develop on current season's growth. It is important not to prune these hydrangeas late in the summer, as flower buds have already formed for the following spring.

Forver a quarter century, Proven Winners Colorchoice™ and Bailey’s Nurseries (Endless Summer™, Bloomstruck™, and Summer Crush™ brands) have introduced the newest hydrangea genetics. The Let's Dance™  series is worth a try in smaller gardens. A second option is to grow a different type of hydrangea Hydrangea serrata, or mountain hydrangea. New in this category from PW Colorchoice is the Tuff Stuff® series which have demonstrated superior bud hardiness and rebloom. Tuff Stuff Ah-Ha® reblooms heavily and has large doubled sepals on lacecap blooms, either pink or blue depending on soil (media) pH._­­­­­

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.

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.

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.

New Hybrid Bleeding Hearts

Dicentra 'Luxuriant' 

Bleeding hearts bloom in April into May (in Tennessee - zones 6 and 7). In cooler northerly locales, flowering may continue into summer.  The bright red, pink or white, heart-shaped, pendant flowers are supported on arching stems.

Bleeding hearts (Dicentra spp.) are truly one of nature’s glorious delights in the spring - early summer garden (USDA hardiness zones 3-9). Old fashion bleeding hearts (D. spectabilis), indigenous to Asia, grow taller and wider compared to their North American counterparts wild bleeding heart (D. exima) and Dutchman's breeches (D. cucullaria).

A number of new cultivars have been released in recent years that are hybrid crosses between D. peregrine (native to Japan) x D. exima (native to eastern North America) x D. formosa (native to Western U.S.). These bleeding heart grow more compact and robust, are longer flowering, exhibit blue-gray foliage, and offer more floral color choices.

Four notable hybrid cultivars include 'Luxuriant' (D. eximia  x D. formosa  - deeply-cut,  grayish-green foliage and cherry red blooms. ‘King of Hearts’ (D. peregrina x D. formosa subsp. oregana x D. eximia) - very compact grower only 9 inches high and 14 inches wide. 'Fire Island' (D. peregrina x D. exima) - white tipped magenta red flowers from late spring into midsummer and 12 inch x 20 inch mound of frosty blue foliage. ‘Valentine’ - a vigorous hybrid form with showy cherry red/white tipped flowers.

New hybrid forms tend to grow more vigorously and are spaced 24-36 inches apart. Good soil drainage is essential for bleeding hearts. Plant in a humus-rich mildly acidic soil along with more hours of sunlight, preferably in the morning. Lightly mulch around plants in a woodland garden. In late winter feed a slow-release fertilizer at the low package rate.

In southern locales hybrid forms generally die back (go dormant) by mid-summer unless regularly irrigated. Crowded clumps should be divided either in very early spring or after flowering.

Spring flowers attract butterflies and hummingbirds. Aphids, slugs and snails occasionally feed on the leaves. Plants are deer and rabbit resistant.

Bleeding hearts are great companions with other woodland plants such as ferns, lungworts (Pulmonaria spp.), brunneras, coral bells (Heuchera), and foam flowers (Tiarella).

Note: in recent times the genus Dicentra has been changed to Lamprocapnos.

Early Flowering Magnolias

'Leonard Messel' Magnolia

Early flowering magnolias (M. ×loebneri ) are excellent choices for a small flowering yard tree. This deciduous hybrid magnolia (M. kobus x M. stellata) includes some hybrid crosses including 'Leonard Messel', 'Ballerini', and 'Merrill'(zones (4)5-9).

Additional hybrid cultivars are also available in commerce that feature more compact forms and flowers (called "tepals") that are white, blush-pink, lilac pink or pink depending on cultivar.

In general, deciduous magnolias start out as slow growing large shrubs or small trees. At maturity they reach 25 feet and a rounded crown. Despite their early blooming, some flowers often escape freezing temps. In the case of first to bloom star magnolia (M. stellata), flowers may open over a 3 week interval.

  

My favorite cultivar in the group is 'Leonard Messel'. This small tree is often grown multi-trunked rather than a single trunk tree. Flowers measure 4-6 inches across with 10-15 petals. Flowers give way to cone-like fruits that age to a reddish tinge in late summer; fruits split open to distribute individual red coated seeds suspended on slender threads. Fruits are sometimes absent on some hybrid magnolias if inadequately pollinated.

Flowering magnolias are best grown in moist, organically rich, well-drained loams in full sun to part shade. Trees are generally intolerant of soil extremes (dry or wet) and intolerant of most urban pollutants. Young trees may take 3-4 years before first blooms appear. Magnolias are best sited in a site sheltered from high winds.

Leonard Messel magnolia has a multi-branched  habit and start producing their lovely flowers at an early age. No serious disease or pest problems trouble this cultivar when properly sited at planting. The 5-inch long, medium green obovate leaves remain blemish-free through the growing season. Its gray bark of deciduous magnolias is an added plus, particularly over the winter months.