Hosta Award Winners

'Niagara Falls' Hosta with dark green, well-defined leaf veining

‘Niagara Falls’ Hosta with dark green Foliage with well-defined veining

Without question, hostas are the most popular perennial for the shade garden. Their lovely foliage provides color, texture and architecture in their garden space from April to a hard autumn frost. They are hardy, long-lived, and relatively maintenance-free.

Hostas range in size from miniature 2 to 3 inches tall types to enormous large leafy clumps 36 or more inches high and broad. Most cultivars grow in shady and semi-shady areas, but a few are sun-tolerant under frequent irrigation. Hostas are also called “plantain lilies” and “funkia”. Their white, lavender, or purple flowers are fragrant. Blooms attract passerby hummingbirds.

The American Hosta Society (AHS) keeps registration records on named cultivars, now numbering over 36,000. AHS members and commercial growers have a voice in selecting the most beautiful and best performing cultivars by region across the U.S. Each year AHS judges award one cultivar their prestigious Benedict Medal.
Benedict Medal winners:
2014 to be announced
2013 First Frost
2012 Niagara Falls
2011 Blue Mouse Ears
2010 Sagae
2009 June
2008 One Man’s Treasure
2007 Whirlwind
2006 Gold Standard

American Hosta Growers choose the Hosta of the Year Award. This outstanding cultivar performs well in most areas of the U.S. and is easy to reproduce. The Hosta of the Year Award is announced two years in advance so that garden centers and nurseries will have plants available for sale.
Hosta of the Year Award winners:
2016 Curly Fries
2015 Victory
2014 Abiqua Drinking Gourd
2013 Rainforest Sunrise
2012 Liberty
2011 Praying Hands
2010 First Frost
2009 Earth Angel
2008 Blue Mouse Ears
2007 Paradigm
2006 Stained Glass
2005 Striptease
2004 Sum and Substance

Crape Myrtle Diseases And Pests

'Hopi' Crape myrtle

‘Hopi’ Crape myrtle

Not all crape myrtle cultivars are alike. Some are more susceptible to diseases and insect pests more than others. Overall, the U.S. National Arboretum (USNA) hybrid crapemyrtles are more disease and insect resistant, but not to all problems.

Some cultivars are susceptible to aphids, usually in the spring. Their sugary excretions over leaves and stems blacken them with a sooty mold. Eventually, leaves yellow and the shrub may bloom poorly. Spray leaves with malathion, diazinon, or an ultra-fine horticultural oil when you spot aphids or the sooty mold symptom.

In late spring and summer, metallic dark green flea beetles may chew the leaf margins in an irregular pattern. Damage is usually slight and does not warrant pesticide spraying.

In late July Japanese beetles chew on the flowers and skeletonize the leaves. Many pesticides are effective to reduce Japanese beetle numbers. Hand removal works but may becomes a daily chore. Pheromone traps are largely ineffective because they attract many more Japanese beetles than they trap.

A strong stream of water from your garden hose can blasted many injurious insects off the foliage. Insecticidal soap sprays are also effective.

Powdery mildew is a fungus disease that deposits a white powdery residue over the leaves and flower buds. Symptoms are worse in high humidity, during lack of rain, and in areas with poor air circulation. If left unchecked your crape myrtle can be weakened and eventually die. Most USNA crapemyrtles are resistant to powdery mildew. Spray susceptible cultivars at the first sign of disease with Funginex™ or Immunox™ and repeat sprays as necessary. Horticultural oil has been shown to be quite effective in controlling powdery mildew.

In the deep South crapemyrtles may shed some leaves with brown spots. This is symptom of Cercospora leaf spot fungus disease during periods of warm, wet weather. In severe cases, only the youngest leaves at the ends of branches remain. Repeated annual infections by cercospora may result in loss of plant vigor and reduced flowering.

These U.S. National Arboretum introductions have some resistance to Cercospora disease: Apalachee, Caddo, Catawba, Sioux, Tonto, Tuscarora, Tuskegee, and Yuma. You can prevent this disease on a susceptible cultivars by spray any fungicide products such as Bayer Advanced Rose and Shrub® or Thiram® when leaf spotting is observed; continue applying the fungicide at weekly intervals through mid-summer.

Versatile Long-blooming Catmints

'Blue Wonder' Nepeta Growing At Kingwood Center, Mansfield, Ohio

Catmint (Nepeta spp.) is a favorite of cats who like to roll around in it, sometimes to the detriment of the plant(s) (USDA hardiness zones 3-8). There are several species of catmint. Most popular are the gray-green leafed N. x faassenii and hairy gray heart-shaped leafed N. racemosa. Depending on the cultivar selected, this versatile perennial grows 1 1/2 to 3 feet high and varying widths.

Catmint grows in average well-drained soil and in full to partial sun (6 hours minimum); shade-grown plants are floppy and flower poorly. One-year established catmints exhibit exceptional heat, drought, and humidity tolerance. Established plants prefer dry (not sopping wet), and low fertility soil.

Catmints bloom from late spring to early fall. Purple, blue, pink or white flowers (depending on species and cultivar) bloom over 3-4 weeks. Prune back plants by two-thirds in late June or July to stimulate August-September re-bloom. Catmints need to be divided every 3 – 4 years in early spring. Cutback old foliage in late winter rather than in the fall.

Plants are highly deer and rabbit resistant. Hummingbirds and numerous nectar gathering bees and butterflies visit the aromatic flowers. Foliage is seaside/salt resistant. The aromatic blooms make good cutflowers and are utilized in floral designs.

Catmint grows in flower gardens, rock and herb gardens, and in containers. Low-growing cultivars work as great edging plants in front borders and as a perennial ground cover.

Popular cultivars:
N. racemosa ‘Walker’s Low’ grows 24 to 30 inches high with blue violet sterile flowers and aromatic grey green foliage (2007 Perennial Plant Association Plant of the Year).
N. x faassenii ‘Six Hills Giant’ is a taller growing catmint (30 to 36 inches high) with dark green leaves and deep violet-purple blooms.
N. x faassenii ‘Blue Wonder’ is a compact grower (12 to 15 inch tall plant and greater spread), dark green leaves, and dark blue blooms. ‘White Wonder’ has white blooms.

Disease Resistant Crape Myrtle Cultivars

‘Apalachee’ crape myrtle trunk

'Sioux' crapemyrtle mildew resistant

‘Sioux’ crapemyrtle mildew & leaf spot resistant

Hybrid crape myrtles (Lagerstroemia indica x L. faurei) are popular landscape trees in the southeast and along the coastal areas of the U. S. Over the past decade plant pathologists in Louisiana (Louisiana State University), Alabama (Auburn University), South Carolina (Clemson University), and Georgia (University of Georgia) have tested the disease resistance of cultivars for powdery mildew and cercospora leaf spot resistance.

Only the cultivar releases from the U.S. National Arboretum are listed below. These are among the hardiest (USDA hardiness zone 6). Each is listed according to its mature plant height:

10 to 15 feet category:

Acoma – white flowers (weeping/cascading habit); light gray-brown bark; high powdery mildew and average leaf spot resistance.

Hopi – medium pink flowers; gray to brown bark; high mildew and average leaf spot resistance.

Sioux – vivid pink flowers; medium gray- brown bark; good powdery mildew and average leaf spot resistance.

Tonto – dark fuchsia flowers; light cream bark; high powdery mildew and leaf spot resistance.

16 to 20 feet category:

Apalachee – light lavender flowers; medium-brown bark; high in mildew and leaf spot resistance;

21-25 feet category

Tuscarora – coral pink flowers; light brown bark; high powdery mildew and leaf spot resistance.

Tuskegee – dark pink flowers; light gray to tan bark; high powdery mildew and average leaf spot resistance.

Over 25 feet category:

Muskogee – light lavender flowers; gray-brown bark; high resistance to powdery mildew average and leaf spot resistance.

Natchez – white flowers; dark cinnamon bark; high powdery mildew and good leaf spot resistance.

Designing With Crape Myrtle

'Dynamite' Crape Myrtle falls in 12-15 feet height category

‘Dynamite’ Crape Myrtle fits in 15-20 feet height category

Undeniably, crape myrtles (Lagerstroemia indica x L. faurei ) thrive in the southern U.S. (USDA hardiness zones 6-9). You see them planted on practically every street. Their showy summer flowers are spectacular. Many cultivars exhibit colorful autumn foliage, and their smooth patterned trunks and architecture grace the winter landscape.

“The right crape myrtle for the right site” is the golden rule here. Before visiting the garden center to make your purchase, measure the intended space where it will be planted. The plant tag will provide the flower color, as well as its height and spread. Is the cultivar hardy where you reside. Cultivars named after Indian tribes (there are 33 of them) are among the hardiest (several zone 6 hardy) and are resistant to some insects and diseases.

“Variety is the spice of life” and crape myrtles surely fit this adage. They serve a number of landscape uses. They make a large deciduous hedge or screen. Plant a single tree for accent or group several together for a formal hedge or screen. Will it be the right size for your site? Dwarf shrub forms as low as 3 feet and tall trees upwards of 30 feet are available.

The larger crape myrtles need room to grow. Stay a proper distance from buildings, power lines, or walkways. Medium-size types grow 10 to 15 feet tall and wide, perfect fits for small urban spaces. The dwarf selections are attractive in large containers or as part of your home foundation. Container plants will require winter protection.

Crape myrtles love sun and well-drained soil. Flower production is greatly declines in light shade and disease problems ramp up in shade. One-year established crape myrtles demonstrate above average drought tolerance.

Become Immersed In Swamp Hibiscus

Swamp Hibiscus (Hibiscus coccineus)

Swamp mallow, aka swamp hibiscus (Hibiscus coccineus) is native to marshes and swamps in South Carolina, Georgia, Alabama, and Florida (USDA hardiness Zones 6 to 9). Vibrant red flowers cover the tall 4-8 foot plant(s) from June through September. Space plants 3 feet wide apart. Deeply cut maple-like foliage presents a lush tropical look and the brightly colored blooms attract hummingbirds and numerous species of butterflies.

Flowers are supported on sturdy beet red and purplish woody stems. The 5-6 inch wide leaves are very hemp-like*, palmately compound, and dark green. Flowering period is long and the showy red flowers become more vibrant with the arrival of cooler weather in very late summer. Most flowering ends at the start of autumn.

It grows best in full to partial sunlight. Shade grown plants become weak and leggy with less flowering; they tend to require staking in shady areas. This native perennial thrives in average moist garden soils. Sunny, hot, wet warm weather revs up its growth rate. Submerge a large container in your water garden. The wetter the site, the taller it grows. A rain garden is another site possibility with backup irrigation called for.

In early summer (and no later), fertilize plants to spur growth and darken foliage. Swamp mallow is borderline winter hardy in Zone 6. Grow in a leeward protected area and protect the plant crown with a loose non-smothering organic mulch over the winter. Overcrowded plants are susceptible to a number of pest and disease problems. In areas plagued with hibiscus sawflies and Japanese beetles, be prepared to spray with carbaryl (Sevin®), malathion, or imidacloprid (Bayer Advanced Insecticide®). Deer tend to leave swamp mallow alone.

* explain to friends and neighbors that swamp mallow is not marijuana.

Mimosa Tree- Love It or Weed It

Mimosa (Albizia) tree in July in Washington DC

Mimosa (Albizia) tree in July in Washington DC

Mimosa (Albizia julibrissin) is essentially a 4-5 month ornamental tree indigenous from Iran to China (USDA hardiness zones 6-9). From late spring through summer, mimosa struts an attractive fine textured foliage and beautiful flowering. This small tree rarely leafs out until mid-May (in zone 6) and offers little in autumnal leaf color. Two seedling forms, either light to dark pink feathery blooms, are common. It blooms from late June thru July and the showy fragrant flowers attract numerous hummingbirds.

Mimosa grows 20-25 feet tall of equal to broader spread. It seems at home under full sun and grows in any soil that is adequately drained. It thrives in subpar soils, often dominating a vacant or abandoned urban lot or growing along a Southeast U.S. roadside fencerow. It likely was not intentionally planted on any of these sites. Yes, seedlings may quickly become a nasty weed invader.

‘Summer Chocolate’ is a recent introduction with stunning dark purple foliage. Chocolate Fountain™ is a soon to be released weeping purple leaf cultivar from Dr. Tom Ranney at NCSU in 2015. New cultivars are attracting new gardeners who like its lacy foliage texture, color and tropics-like foliage. I urge cutting mimosa in early fall to prevent seed dispersal. Gardeners may opt to grow the foliage and forego flowering.

The notion that mimosa is an exotic invasive is debatable. Trees are not long-lived, rarely more than 20 years old. They improve the soil’s tilth and nutrition, so that one day, an opportunist native species will shine in its place.

Late winter thru early summer (February-July) is the ideal planting time. Remove unwanted and dead branches at anytime. Fertilizing mimosa trees is unnecessary as roots fix their own nitrogen.

Caveats Before Planting Planetrees (Sycamores)

American sycamore main trunk

American sycamore main trunk

American sycamore, aka planetree, (Platanus occidentalis) is a native tree planted over a large area of the United States (USDA hardiness zones 4-9). Its enormous size, often 70-90 feet in height, limits it to planting mostly on large landscapes such as parks, golf courses, and industrial parks. Northern U.S. cities have planted it extensively along major thoroughfares, wide avenues and boulevards. Sycamore is commonly utilized in reforestation work because it grows in a great variety of soils, wet or dry, and copes with most environmental situations including urban pollution.

Smooth white patchwork bark is its most identifiable winter feature. Chunks of bark, sometimes quite large, flake off to reveal a chalky white inner bark. Caveat: sycamore (planetree) is a messy tree. Chunks of fallen bark, gumball fruits, and numerous twigs, add up to a potential maintenance nightmare. Seedling trees are susceptible to spring leaf anthracnose, aphids, and lacebugs. Damaged leaves will litter lawn areas in mid-spring; the arrival of warm dry summer weather usually checks the disease and insect onslaught.

Sycamore grows very rapidly in either full or part sun (6 hours preferred). The roots of older trees tend raise up sidewalks and clog water, sewer and septic lines. Despite numerous pest and disease issues, American sycamore grows very aggressively,gaining in size and stature. Do not crowd trees close together to allow good air movement and less disease outbreaks.

London Planetree (P. x acerifolia) is a cross between Oriental planetree (P. orientalis) and American sycamore. Its disease resistance has made it the better choice and one of the most popular large trees in urban Mid-Atlantic and Midwest states (USDA hardiness zones 4-9). Good disease resistant cultivars of hybrid planetrees include ‘Columbia’, ‘Liberty’, ‘Yarwood’, and Exclamation™.

Japanese Pagoda Tree Becoming Popular In U.S. Cities

Japanese Pagoda Tree in Raleigh, NC

"String of Pearls" Fruits

U.S. east coast cities are finally planting Japanese Pagodatree (Styphnolobium japonicum). This medium-sized tree grows to 50 feet high, but 75 feet is not uncommon in the southeastern U.S. Pagodatree is native to eastern Asia (USDA hardiness zones 4 –8) where it is more known as Scholar tree. In the early 20th century it was frequently seen planted around schools and Buddhist temples in Japan.

Pagodatree grows in full to partial sun (6-hours minimum) and in a moist well-drained, slightly acidic soil. Pagodatree tolerates urban drought, air pollution, and moderate salinity around coastal areas. The tree has no serious disease or insect problems. A small number of cultivars, including weeping and upright (columnar) forms, are listed.

‘Regent’ is the most popular cultivar, high valued as a vigorous grower and lustrous green foliage. A newly planted tree blooms earlier and exhibits superior disease resistance than the species. Annual growth rate ranges from 18 to 24 inches. Summer foliage is comprised of 8-10 inch long, pinnately compound leaflets numbering 7 to 17. In some years its golden fall color can be spectacular.

What really makes pagodatree special is its July-August flowering time, when few landscape trees are blooming. Its pea-like, creamy-white flowers are showy and fragrant. Flower clusters, 12 inches long and wide, drape from branch tips. Another unique feature is the 3 to 8 inches long green “string of pearls” fruits which form in late summer and persist way into fall. Birds don’t appear drawn to the berries which shrivel to black and linger through the winter. By spring the tree has self-pruned many of the twiggy fruit rachises.

A young pagoda tree exhibits a semi-upright, vase shape habit and develops a full rounded canopy as the tree ages. A mature tree exhibits a lovely grayish-brown furrowed bark. Pagodatree is related to Mescal Bean tree (Calia secundiflora), native to Southern Texas into Mexico (Zones 8-10).

Blazing Star– Electric Summer Flowering Perennial

Blazing star (liatris)

Blazing star (liatris)

Blazing star (Liatris spp.) is a popular summer flowering perennial. Also called gayfeather, it belongs in the aster family. This tall, upright, clump-forming perennial is found in moist meadows and at the edge of a marsh. (USDA hardiness zones 3-9). Liatris makes an excellent addition to a rain garden.

Its distinctively reddish-purple flower spikes win over a lot of gardeners. Individual flowers, each only ¾ inches across, comprise the floral head which open from the top down to the base. White blooming forms are also available. Multiple stalks rise from the crown, cloth in narrow, grass-like, medium-green leaves. Stem leaves are long and gradually decrease in size near the top. L. spicata ‘Kobold’ is an outstanding compact cultivar that has become the standard bearer in most gardens.

Blazing star grows 2 to 5 feet tall, depending on the fertility of the garden soil. Space plants 12 to 18 inches apart. Once established, plants require very little care. They thrive in their garden space upwards of 3 years, then should be divided, or replaced with new plants.

Blazing star grows in average well-drained soils in full sun. This prairie species is not tolerant of poor drained soils, particularly soggy soils in winter. It excels in moist, fertile soils. Other Liatris species demonstrate better drought tolerance. It’s tolerant of summer heat and humidity. They can be grown from seed, but some are slow to establish. Kobold may spread from seed in its garden spot.

The brightly colored blooms attract numerous birds, butterflies, and unfortunately rabbits. Deadheading will spur re-bloom within 4-5 weeks. A mid-summer fertilizer is advised. Blazing star suffers from no serious insect or disease problems. Taller plants may require staking or other support; ‘Kobold’ rarely requires staking. Flowers make excellent fresh and dried cutflowers.