What Grows There :: Hugh Conlon, Horticulturalist, Garden Advisor, and Photographer

Chinese Fringetree

Posted by Hugh on May 6th, 2022

Chinese fringetree (Chionanthus retusus) is native to China, Korea and Japan (USDA hardiness zones 5-9). As with the native U.S. species (C. virginicus), this plant is noted for its fragrant white flowers. Gardeners first fall in love with this large, multi-stemmed, deciduous large multi-branched shrub. Some nurseries are also offering the Chinese form as a promising 20-30 feet tall, low-branched, (single or multi-trunked), lawn tree.

Fringetrees are primarily dioecious (separate male and female plants), but some perfect flowers do occur. Male flowers are slightly larger and showier. Female flowers (if fertilized) give way to clusters of olive-like fruits (each to 1/2” long) which ripen to a dark bluish black in late summer/fall and are a good food source for birds and wildlife.

Lustrous, leathery leaves are ovate to elliptic and 4” long. Leaves on young plants have serrate margins. Leaves are bright green above and downy whitish green beneath. Leaves turn yellow in fall (reportedly more attractive in northern areas). Exfoliating gray-brown bark is attractive in winter.

Chinese fringetrees require little special attention. Best flowering happens with 4-5 hours of sun. Site the tree in average, medium moisture, mildly acidic, well-drained soil. Young 1–2-year-old trees should be irrigated during dry spells lasting 10 days of more. Pruning is rarely needed. Leaves are tolerant of air pollution and adapts well to urban settings.

No serious disease and insect problems trouble Chinese fringetree. Occasionally, damage from mites, scales and borers have been reported, usually observed during stressful hot dry summers. Leaf spots, canker and powdery mildew diseases may occur as signs of over-irrigation or wet summer weather.

Fringetrees, both the U.S. native and Chinese forms, are rarely sold at local garden centers, but are available in limited numbers at online nurseries. They’re spectacular in full bloom and early evening fragrance is so worth it.

Noted cultivar – ‘Tokyo Tower’ is a narrow upright branched small tree. It grows 12 – 15 feet tall and 4 – 6 feet wide. In the spring (early May), its narrow stature standouts abundant clusters of billowy white flowers followed by blue berry (drupe) fruits ripening after mid-August; dark green foliage turns yellow in autumn. Fall color is variable from one year to the next.

Rough Bark at Biltmore Estates, Asheville, NC

10 Drought Tolerant Perennials

Posted by Hugh on May 1st, 2022

Once established, these ten drought-tolerant plants can cope with hot sun and humidity with low amounts of supplemental water. If you garden in a drought-prone area, or growing in fast-draining raised beds, these drought-resistant plants are a great choice for your garden. Perhaps you wish
to reduce your water bills. Plan to keep plantings adequately mulched during the season.

Purple coneflowers (Echinacea purpurea) are tough and pretty. Purple is the most common flower color, but white, orange, red and yellow varieties are available. New series such as Sombrero®, Artisan™, PowWow®, and Cheyenne Spirit® grow only 16 to 30 inches tall with non-stop blooming from June to September. Leave the dead flower cones to be visited by goldfinches or other birds over winter. (Z 4-9)

Butterfly weed (Asclepias tuberosa) – the iconic, bright orange beauty that’s a staple in every butterfly garden. This showy native wildflower is easy to grow, cold hardy, and does well in poor, dry soil

Yarrow (Achillea millefolium)- dazzling red-violet highlight into your pollinator garden. Compact fern-like foliage softens sturdy upright stems. var. Sassy Summer™series

Lavender (Lavandula x intermedia)- forms a compact shrub with aromatic silvery gray-green narrow leaves with long flowering stems are topped by 5 inch spikes of sweet scented bright violet-blue flowers. Often repeat blooms in late summer or fall. var. Phenomenal™ and ‘Provence’.

English Lavender (Lavandula angustifolia) – compact English Lavender like the varieties ‘Hidcote’, ‘Munstead’, or ‘Superblue’ grows 12-24 inches tall, with highly fragrant, deep purple-blue flowers; best planted for edging walkways and in patio containers.

Red Hot Poker (Kniphofia) – fiery colored flower spikes will lighten up your garden. Red-orange- mango-yellow buds, depending on variety, open from bottom to top. Cutoff spent floral stalks and it reblooms in 4-6 weeks. Try ‘Popsicle™ or ‘Pyromania™ series

Russian Sage (Perovskia atriplicifolia) – dwarf varieties like ‘Little Spire’ and ‘Denim N’ Lace’ tall, airy spires of lavender-blue color on highly-textured silver-gray foliage all summer long. low-maintenance, great choice for xeriscaping. Deadhead for continuous bloom.

Anise Hyssop (Agastache foeniculum) – very long blooming perennial (zones 6-10). var. ‘Blue fortune’, ‘Peachy Keen’, Kudo™ and Poquito ™ series

Feather Reed Grass (Calamagrostis) – creates a dramatic garden accent, with tall, slender, vertical growth and feathery plumes of shifting bronze color that stay in place year-round. var. ‘Karl Foerster’, ‘Avalanche’, ‘Overdam’.

Ground Hugging Sedums – a carpet of changing colors that grow only 4 to 6 inches tall and spreads to 24 inches wide. Popular examples: Sedum spurium ‘Dragon’s Blood’, S. ‘Cherry Tart’; S. reflexum ‘Blue Spruce’, S. ‘Neon’, S. rupestre ‘Angelina’. Leaves of some may take on red-orange-yellowish tones in autumn. Star-shaped yellow, ½ inch wide flowers in summer.

Caveat: this information is not relevant to perennials growing in containers.

Heartleaf Iceplant (Aptenia)

Posted by Hugh on April 26th, 2022

The world of succulents is a treasure trove for many cool garden plants that attract many collectors, including house plant enthusiastics. Heartleaf iceplant (Aptenia cordifolia), also called Baby sun rose, is a non-hardy succulent or evergreen ground cover.

This herbaceous subshrub is indigenous to South Africa and favors a Mediterranea- like climatic conditions (in USDA hardiness zones 9-12). Aptenia is closely related to hardy iceplant (Delasprema cooperi). Both genera are found in the botanical family Aizoaceae.

Heartleaf iceplant loves light, but you may need to shelter leaves from direct sun during extreme heat and dry periods. Keep it moderately watered can potentially harm the leaves. In temperate regions, it is beloved for its thick green foliage in spring-summer gardens and nurtured indoors as a houseplant in a well-lit room. Heartleaf iceplant tolerates to dry periods. Treat it as any other cactus or succulent and water this as you would water others in your home. Avoid extremes of overwatering and drought.

Heartleaf iceplant can be propagated from seeds and by cuttings. Seeds can be purchased online plant shops or snip 4-5-inch-long cuttings from garden plants in early fall before cold weather arrives. Pot rooted cuttings and seedlings in a well-drained soil-less media.

Aptenia creates a colorful foliage and flowering plant. In a garden container, utilize as a filler or a chiller to drape over the edges of containers. Flower colors include red, purple, pink, and white; flowers are comprised of strap-like multi petals.

Four Space-Saving Summer Blooming Shrubs

Posted by Hugh on April 21st, 2022

Miniaturation of many of our garden shrubs has been a trend for over 30 years. A common saying among gardeners has been they no making any more land making anymore or, in this case, garden planting space. In particular, urban gardeners continue to squeeze more color into limited spaces. Here are four flowering shrubs that are very successful.

Chaste tree (Vitex agnus-castus) is now available in shorter shrub forms. Standard Vitex growing to 15-25 feet. Spikelets of lavender-blue flowers appear in mid-summer. Thus far, varieties Blue Diddley® and Blue Puffball’™ are available, but many other varieties, including white and pink-flowering forms, are coming. ‘Blue Puffball’ grows only 3-4 feet tall and wide in a near perfect ball-shaped plant with deep blue, fragrant flowers from June through September. ‘Blue Diddley’ grows 5-6 feet tall. Flowers form on new growth. In the north (zones 5-6), Vitex performs as a perennial and dies back to the ground; it regrows and flowers much like a butterfly bush (buddleia). (Non-native)

Cherry Dazzle® or Berry Dazzle® Crapemyrtles (Lagerstroemia indica) have proven to bloom reliably from one year to the next in zone 6. Plants require minor cleanup pruning in early spring and a handful of 10-10-10 fertilizer. Bot cultivars grow 3 to 3.5 feet tall and are covered with red flowers in midsummer (late July-August). (Non-native)

Pugster® series of Buddleia x davidii) is a new compact plant, only 2 ft. tall and wide but with the full-size flowers on sturdy stems. The Pugster series bloom non-stop from early summer through frost with true-blue flowers, each with a tiny yellow-orange eye in the center. The Pugster® series is available in four colors: Pugster Blue, Pugster Periwinkle, Pugster Pink, and Pugster White. All cultivars offer vastly improved cold hardiness and winter survival over other types of dwarf butterfly bush (zones 5-9). (NonNative)

Wee White® Smooth hydrangeas (Hydrangea arborescens ‘Wee White’) is a dwarf ‘Annabelle’ like hydrangea, just 1-2.5 feet tall. The shrub develops into a tidy, rounded mound. Flowers emerge a soft, blush pink before changing to white on a sturdy stem. All new flowers develop from early summer to frost. (Native)

Bobo® Panicled hydrangeas (Hydrangea paniculata ‘Bobo’) grows only 3 feet tall, along with large creamy white summer flowers held upright on strong stems. Flowers finish with a pinkish hue in fall. (Non-native)

Photo credits: Thank you to Spring Meadow Nursery for Vitex ‘Blue Diddley’ and Buddleia ‘Pugster White’ photos

Next Generation Of Kousa Dogwoods

Posted by Hugh on April 16th, 2022

*Cornus kousa* ‘Scarlet Fire’ (photo by Dr. Thomas J. Molnar)

‘Scarlet Fire’ is a 2017 introduction from Rutgers University with 4-5 inch wide, fade-proof, dark pink floral bracts. This Kousa dogwood tree is also heat and drought tolerant and highly disease resistant.

‘Wolf Eyes’ is a compact tree (10-20 feet tall) or multi-branched shrub form; creamy white variegated foliage is scorch-resistant. Wolf Eyes flaunts eye-catching gray-green leaves with wavy margins. Star-shaped white flowers which fade into the strongly variegated foliage. Bright-red berries follow in late summer. Slow growing specimen.

Venus® is another hybrid dogwood (Cornus kousa ‘Chinensis’ x C. nuttalii ‘Goldspot’ x C. kousa ‘Rosea’) bred at Rutgers University. Venus is noted for its vigorous habit, large-bracted flowers, profuse bloom and disease resistance to anthracnose and powdery mildew. The unusually large floral bracts measure 6–7 inches across. This small (20-25 feet tall) deciduous tree has a dense, low-branched, spreading habit.

Little Ruby® is compact shrub that’s great utilized in mass plantings. It is equally beautiful as a miniature specimen tree. The semi-double pink flower bracts are very attractive with bright red leaves on new spring growth. Leaves turn rich maroon in summer and persist late into fall. It also exhibits excellent disease resistance (zones 6-10) and is semi-evergreen to 15°F. Little Ruby roots easily from cuttings.

‘Little Poncho’ is a diminutive dogwood, 8-10 feet tall, ideal for planting in small garden spaces and large containers. It creates multi-seasonal appeal with creamy white spring flowers, spring and summer pest-free dark green foliage, and finishing with decorative raspberry-like fruits and maroon, red leaf color in fall.

*Cornus kousa* ‘Poncho’ on ETSU Campus in Johnson City, TN

Roof Iris in Springtime

Posted by Hugh on April 11th, 2022

Roof iris (Iris tectorum) is indigenous to China. This beardless iris is part of the crested iris group. Leaves stand 15 inches tall, fanned at the base and are ribbed. The clean green fan-like leaves remain mostly blemish-free most of the growing season. Plants give rise to purple-blue flowers with white and darker purple flecks starting in late April (in Tennessee) and and remain showy for 2-3 weeks in May (USDA hardiness zones 4-9).

Roof irises are very adaptable and sturdy plant that prefer a partial sunny to part-shade site. In northern gardens plants may tolerate direct sunlight, and a lot less, only 2-4 hours in the South and preferably just morning sun. Roof irises grow in a humus-rich, well-drained soil. They are low constant feeders; simply a dressing of compost or aged manure in fall; or a bit of low nitrogen (5-10-10) fertilizer in spring; or a slow release organic fertilizer.

Roof irises may be grown in wet soils, such as around ponds and fountains. They can be used in rock gardens, but may need occasional watering over extended dry periods. After many years the rhizomes will spread and the roof iris naturalizing. Historically, “Roof Iris” were utilized for thatched roofs in its native China.

Roof iris are susceptible to slugs and viruses. The latter pests cause leaf yellowing and streaking and may lead to a general decline of a clump. If this occurs, remove and destroy the plants. Roof irises are deer tolerant.

Cultivars: ‘Woolong’ is a popular clone from Woolong in Sichuan, China; fan-like leaves reach 15 – 20 inches tall and 2 -3 feet wide clumps with lavender blooms with purple flecks in May. ‘Slippery Slope’ forms tight-clustering 30 inches wide large clump with 2 feet tall blue-purple floral spikes; falls with a lovely white eyezone etched with purple line. ‘Alba’ produces frilly white flowers above the foliage. All three are sold by Plant Delights Nursery, Raleigh, NC.

Three Standout Panicle Hydrangeas

Posted by Hugh on April 6th, 2022

For over a decade the cultivar ‘Limelight’ has been among the best selling panicle hydrangeas (Hydrangea paniculata) (USDA hardiness zones 3-8). It bears large greenish-white floral trusses on 6- 8 feet tall branches; beautiful for use as cut (fresh or dried) flowers. Here are three panicle hydrangeas that are also very popular.

Vanilla Strawberry™ hydrangea (H. paniculata) is a cultivar of peegee hydrangea introduced from France and is catching on across the U.S. The shrub typically grows to 6-8 feet tall and to 4-5 feet wide. New blooms open green, gradually age to blushing pink, and finish rosy pink. Blooms are enormous and stand upright. Following a summer rain, the heavy water soaked floral trusses may temporarily bow down, but gradually straighten up as the blooms dry out.

Quickfire® is the earliest blooming panicled hydrangea. The lace cap flowers start out pure white, turn pink with age, and mature dark rosy-pink in fall. The shrub grows 6-8 feet tall and flowers are visited by pollinators. New variations in the Quick Fire series are also available: Little Quick Fire® and Quick Fire Fab®.

Bobo® is a dwarf panicle hydrangea that bears large white flowers in summer, held upright on strong stems. That means no flopping. The blooms age to pale pink in early fall. Plants grow only 2.5 – 3 feet high. The mostly sterile flowers do not attract many pollinators.

General Care: PG hydrangeas bloom at its fullest in full sun in zones 6 and points north. In southerly climes, provide full morning sunlight and moderate afternoon shade. PG hydrangeas thrive in moderately moist, well-drained soil. Feed in early spring with a slow-release fertilizer such as Osmocote™ or Nutricote™. Apply 2-3 inches of an organic mulch in spring to conserve soil moisture. Irrigate during long summer dry spells. Prune back plants by one-third of their total height in early spring.

Globe Amaranth (Gomphrena)

Posted by Hugh on April 1st, 2022

Three important objectives of area gardeners are: 1. Inviting more pollinators, 2. Growing more natives, and 3. Reducing garden maintenance. Gomphrenas, aka Globe amaranths, are becoming more recognized as outstanding annual flowering plants for Tennessee/Virginia/North Carolina gardens. Gomphrenas are North American natives (Texas, New Mexico, and northeastern Mexico) and are blooming machines in the heat, the humidity, and droughty soils of summer.

Gardeners often reach for showy big flowering annuals. However, small ball-shaped clove-like gomphrena blooms are covered with throngs of bees, butterflies, and other nectar feeders in garden beds and containers. Gomphrenas root down deeply and bloom spring, summer, and way into autumn, wanting very little care.

Gomphrenas grow 10 to 24 inches high and 12 to 16 inches spread. The color floral palette comprises purple, pink, orange-salmon, and red. They prosper in full sun and will grow in poor to average ground as long as soil drainage is good. Space plants a foot or so apart. Spread a slow-release fertilizer such as Osmocote™ at planting time. If leaves appear chlorotic in summer, apply a water-soluble fertilizer such as Miracle-Gro™ or Peters™ to green-up plants. Gomphrenas planted in the spring are usually well established in 4-6 weeks. Afterwards, summer watering needs are minimal.

Gomphrenas attract very few pests and disease problems. Rabbits and deer generally stay away. Spider mites are sometimes troublesome if summer weather is exceptionally dry. A coarse spray of water directed to the underside of leaves will reduce mite populations without use of pesticides.

So many great choices!! Long-stemmed Gomphrena haageana grow taller and not as wide as G. globosa. Distinctive G. globosa cultivars include: bright fuchsia ‘Fireworks’, stoplight red ‘Strawberry Fields’, and ‘Lavender Lady’. ‘Fireworks’ are described as “explosions of pink with yellow stamen flowers”. In 2020 a huge hit among visitors to the UT Gardens in Jackson was G. pulchella Truffula™ Pink with “tufted, hot pink orbs with the bracts tipped in tangerine”. It grows slightly smaller than ‘Fireworks’, another gardener favorite.

Audray™ series are available in Bicolor Rose, Pink, Purple Red, and White. LasVegas series (white, pink, purple) are also standouts. See Gomphrena photos on SAPS website. Gomphrena flowers are especially nice in mixed fresh floral bouquets for the table and in dried florist arrangements.

2022 Perennial Plant of the Year® Announced

Posted by Hugh on March 31st, 2022

2Since 1990 The Perennial Plant Association (PPA) has showcased a perennial that is a standout among its competitors! Perennials chosen for this honor are suitable for a wide range of growing climates, require low maintenance, have multiple-season interest, and are relatively pest/disease-free. Each year PPA members look at four nominated perennials and vote for their favorite. PPA members vote for the Perennial Plant of the Year® and nominate additional plants for the following year’s ballot. In addition, members have access to a flyer, poster, and bench card to assist with promoting the Perennial Plant of the Year®.

The PPA is pleased to promote Little bluestem (Schizachyrium scoparium and cultivars) as the 2022 Perennial Plant of the Year®. The wider selection of Schizachyrium scoparium and cultivars allows the perennial expert in any region to select and promote the cultivars that do best in his or her location!

PPA Board members selected top performers in their regions and shared appealing details about each one. Highlights of each selection are below:

Central region – Richard Hawke of the Chicago Botanic Garden selects Schizachyrium scoparium ‘Jazz’ for the Central region. Richard notes, “The striking silvery blue leaves of Schizachyrium scoparium ‘Jazz’ are most comparable to ‘The Blues’, but at 36 inches tall and 30 inches wide, ‘Jazz’ is a foot shorter than ‘The Blues’ and has sturdier stems.

Southern region – Shannon Currey of Hoffman Nursery selects Schizachyrium scoparium ‘The Blues’ for the Southern region. Shannon comments, “In the South, our humidity, high nighttime temps, and wet springs can slow down some Little Bluestem. ‘The Blues’ is a strong, vigorous grower and has fantastic color. Blues, pinks, purples in the summer followed by reds and oranges in the fall. In the right conditions, it stands out for us.”

Canadian region – Tony Post of Brookdale Treeland Nurseries – Valleybrook Farm, choses Schizachyrium scoparium ‘Standing Ovation’ for the Canadian region. Tony says, “This selection adds excellent texture to the summer garden. Burgundy highlights add late season interest. Seed heads are attractive, particularly when backlit.”

Western region – For the Western region, Nanci Hollerith Allen of MarkWatch Plants notes that Schizachyrium scoparium can be a tricky plant unless you have reasonably dry, well-drained soil. She shares two recommended cultivars for the Pacific Northwest and the Rocky Mountain region: Schizachyrium scoparium ‘The Blues’ and Schizachyrium scoparium ‘Standing Ovation’.

Great Lakes region – Patty Steinhauser of Stonehouse Nursery chooses Schizachyrium scoparium ‘Carousel’ for the Great Lakes region. Patty says that, “This uniquely mounded selection forms a wide clump of blue-green foliage that emerges nearly horizontal and matures into strong, upright stems that remain standing through inclement weather and winter. It takes on pink, copper and orange-red tones in fall topped with tiny seed tufts.”

Mid-Atlantic region – Taylor Pilker of Cavano’s Perennials suggests ‘The Blues’, ‘Standing Ovation’, and ‘Jazz’. Taylor likes ‘Blue Heaven’ because “it is taller and has good autumn color with a wide range of shades of burgundy and pink.”

Information source: Perennial Plant Association website

Coneflower Variety Trials At MT. Cuba Center

Posted by Hugh on March 26th, 2022

Echinacea planting at Kingwood Center, Mansfield, Ohio

Coneflowers (Echinacea spp) are immensely popular native flowering perennials prized for their summer floral beauty. Nine species of Echinacea are native in North America and are found primarily in the central and southeastern U.S. Additionally, some populations of Echinacea angustifolia extend from the U.S. northwards into southcentral Canada.

Since the 1990s, a boom in Echinacea breeding has resulted in large numbers of new cultivars arriving at garden centers. The result has been an endless array in diversity, particularly in plant sizes and flower colors of coneflowers.

In 2020 MT Cuba Center in Greenville, DE released their most up to date ratings. This represents an updated test summary from their previous 3-year Echinacea variety trial in 2007-2009. The new report lists many more coneflower introductions and compares some newer cultivars against some of the tried-and-true top performers from the 2007-2009 trial.

In addition, MT Cuba conducted a pollinator survey to determine the cultivars that were most attractive to pollinating insects. This data was collected by their Pollinator Observation group. They tallied insect visitation to help determine ecological value of plants in our trials. For Echinacea, special attention was paid to the difference between single and double flowers in their ability to attract pollinators.

The best performing coneflowers in the trial are E. purpurea ‘Pica Bella’, E. ‘Sensation Pink’, E. ‘Santa Fe’, E. ‘TNECHKR’ (KISMET® Raspberry), E. ‘Snow Cone’, E. ‘POST301’ (Postman), E. ‘Glowing Dream’, E. ‘Purple Emperor’, E. purpurea ‘Fragrant Angel’, E. ‘TNECHKIO’ (KISMET® Intense Orange), E. ‘Balsomcor’ (SOMBRERO® Hot Coral), and E. ‘Julia’.

Important to gardeners: if you live in the mid-Atlantic States, results from the MT Cuba trial should be most useful and are posted online on the MT Cuba website. Midwest gardeners should look to recent Echinacea evaluations at the Chicago Botanical Gardens.