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

Chinese Paperbush (Edgeworthia)

Posted by Hugh on February 10th, 2025

If you garden in winter hardiness zones USDA zones 7 -10, Chinese paperbush (Edgeworthia chrysantha) should be a must-have winter flowering shrub. In my zone 6-b garden, my shrub struggled through its first winter and spring, but paperbush has never disappointed over its past 20 + years. A few gardeners living near me are also enjoying great success.

Paperbush is not difficult to grow and is fascinating to watch as cold temperatures moderate in early March. The uniquely nodding floral buds are clearly visible on branch tips in early fall. Fragrant flowers open in late February, weather permitting. The tubular clusters of flowers are light yellow on the inside and white on the outside. After a number of years roots may sucker new plants, forming a small plant colony.

Paperbush is a multi-stemmed 4-5 feet tall shrub with lovely greenish blue foliage. The new growth is coated with fur-like reddish brown hairs. Paperbush belongs in a woodsy environment under dappled shade in the summer and protected from prevailing winds.

Summer isn’t a downtime for the paper bush. After it finishes blooming, paperbush cloaks itself with velvety soft foliage reminiscent of tibouchina or plumeria. Long, narrow, blue-green leaves are almost tropical looking and measure up to 10-inches long.

At the start of autumn, new drooping, rounded flower buds are forming, covered with silky, silvery hairs atop of naked stems. When sunlight hits the buds, the paper bush seems to bloom already. The flower buds grow in size and prominence most of the winter.

By late winter, flower clusters have popped open to reveal pendant clusters of dainty white tubular blooms on the outside, tipped with yellow. Its sweet fragrance reminds you that paper bush is akin to winter daphne. Flowering lasts 4 to 6 weeks, sometimes longer.

Paperbush is hard to find for sale at family-owned garden centers. You definitely should search this collector’s plant at e-commerce nurseries which sell out quickly. A number of cultivars are entering the marketplace, some at steeply high prices.

Cultivars:

‘Snow Cream’: Boasting large clusters of highly fragrant, golden-yellow flowers, this variety is supposedly more cold-hardy than regular paper bush (down to 0°F).
‘Akebono’ (‘Red Dragon’): This variety features orange-red flowers in late winter and spring and grows slower and more compact than other species. grow 8 feet high and wide. (zones 7b-10).
‘Grandiflora’: species with the largest flowers.
‘Ruby Splash’: This variety is rare and contains red flowers.

Lots of Choices Growing Monstera

Posted by Hugh on February 2nd, 2025

*Monstera deliciosa* – often called Split-leaf philodendron

In recent years, Monstera plants have become wildly popular house plants. They’re indigenous to tropical areas of Central and South America. Approximately 50 different species are available at plant shoppes or online. It is an understory plant that grow in the shade of tropical trees and other vegetation.

Plants prefer filtered indirect light and avoid full direct sunlight. If plants get leggy, adjust the light setting for your monstera. Some varieties can take nearly full 1/2-day morning sun indoors. Contrarily, some variegated foliage types can burn in bright room light.

Monstera plants prefer a well-drained organic medium for most other tropicals at plant shoppes. Plants also produce aerial root systems that may take root in potting mix.

Plants prefer temperatures from 60° – 85°F and moderate humidity levels around 40- 50% for optimum growth. Daily misting of foliage and exposed air roots will raise room humidity levels. Wipe leaves monthly with a damp cloth to remove dust.

Feed @ 50% fertilizer strength (read package directions) once monthly and hold back feeding during the winter months.

Prune Monsteras to encourage new growth, limit plant height, and remove old, damaged foliage.

Monsteras can be propagated in water, peat-perlite mix, air layering, and root division. Grow it in a hanging basket as a cascading plant or trellised on single osmunda, coir, or moss trellis pole.

Popular Monstera Species:

Monstera deliciosa Split-leaf philodendron or “Swiss cheese plant”, – large, rounded leaves full of holes; slow-grower climber or creeping stem that is often trellised.

Monstera adansonii, – another “Swiss cheese plant” – oval to heart shape leaves, with about 5 holes per leaf; grows only 3 to 5 feet high.

Monstera epipremnoides – grows tall with big leaves and perforated leaves that drape over one another.

Monstera obliqua, aka Swiss Cheese plant, – a rare, slow-growing form with large holes in the leaves form.

M deliciosa alba borsigiana – variegated form highly coveted for its large white bands that contrast with the green foliage; leaves burn easily compared to solid green forms.

M. deliciosa ‘Thai Constellation’ -fast-growing variety with vining stems with small, variegated foliage that is splashed and speckled.

Caution: plant sap can cause irritation to the skin, eyes, mouth, and digestive tract; wear gloves when pruning and wash your hands thoroughly after handling the plant.

*Monstera obliqu*a or Swiss Cheese Plant

Slipper Orchids (Paphiopedilum)

Posted by Hugh on January 28th, 2025

Slipper orchids (Paphiopedilum spp.) are a type of terrestrial orchid known for their pouch-shaped petals that resemble a dainty slipper. Paphs are low light tropicals. Unlike epiphytic orchids, which grow in trees in the humid tropics, these orchids grow on the floor of forests in their native Southeastern Asia.

Paphs are relatively easy to grow indoors as houseplants and thrive with high humidity, medium indirect light, and moist soil. According to the Atlanta Botanical Gardens, most slipper orchids like night temps between 58° and 62°F. and daytime temps between 70° to 85°F and like moderately humid environments ranging anywhere from 40-70% humidity. Use a small room humidifier or set the plant(s) atop a tray filled with moistened pebbles. Never leave the pot sitting in water.

Paphs should be place with medium indirect light. Indirect light from an east-facing window is ideal. You can also put your paphs near a south-facing or west-facing window as long as they’re shaded by a sheer curtain. Plant in a fine fir bark/peat moss/perlite potting media, well-drained growing medium and water once or twice weekly. Use tepid, room temperature water). Paphs are not drought tolerant.

Fertilize with a balanced orchid fertilizer after each watering. Diluted to one-quarter strength fertilizer once weekly. Once per month, flush the growing medium well by running water through the pot for 10-12 seconds to help wash away excess salts.

Paph Orchid at Biltmore Estates Conservatory, Asheville, NC

Lady slipper orchids typically bloom between fall and late winter, depending on the variety. There are several types of paphiopedilum orchids, including the mottled leaf paphs (called ‘Maudiae’ hybrids). They have light green leaves dotted with dark green splotches and bloom with one or two long-lasting flowers once annually. Maudiae prefer warm temperatures and require less light than other lady slipper types, making them easier to grow indoors.

Generally, repot paphs every 2 years, usually when plants are crowded and/or need dividing. New growth usually appears in spring—never during flowering. A good orchid mix contains fine fir bark, peat moss, and perlite. Paphs can be grown in plastic or clay pots. Utilize clean sharp pruners or shears. Once your plant has finished blooming, usually after 6-8 weeks, cut off the old floral spike down to the leaves. It should bloom again in about a year.

Paphs are susceptible to common houseplant pests, including mealybugs and scale. Overwatering plants can result in root rot and eventual death. Yellow leaves can be a symptom of overwatering.

2025 Hosta OF The Year: ‘Skywriter’

Posted by Hugh on January 26th, 2025

Hosta ‘Skywriter’ has been selected as the 2025 Hosta of the Year. by the American Hosta Growers Association. ‘Skywriter’ is a blue hosta with a semi-upright habit that shows off the white undersides of the leaves and the purple stems (scapes). (USDA Hardiness Zones 3 -8). It is a medium-sized hosta, that grows approximately 18 inches tall and 4 feet wide.

‘Skywriter’ was bred by Dan Wols, a Chicago-area dentist and hosta hybridizer. Its breeding background includes two strongly blue cultivars: ‘Smoke Signals’ and previous hosta award winner ‘Neptune’. Add ‘Marilyn Monroe’, a green rippled leaf hosta to its bloodline.

The solid blue ruffled edged foliage and corrugated textured surface complement the pale purple flowers that appear in summer. The backsides of the leaves are white and are evident due to the plant’s slightly upright habit. The ruffled leaves are attached on bright purple petioles. Lavender flowers sit atop the purple scapes that adds cool blue-color accent in your hosta garden

Plant in a well-drained, humus-rich garden soil. Protect ‘Skywriter’ foliage from harsh sun. Ideally, site this hosta in bright morning sun with filtered afternoon shade. If sun intensity is too harsh, the wax on the leaf deteriorates the bluish tint.

To show off ‘Skywriter’ in your garden, compliment with bright colored perennials such as bright yellow-, orange- or red-leaved coral bells (Heuchera) /(Heucherella), Brunnera ‘Jack of Diamonds’, Chinese astilbe, and pigsqueak (Bergenia).

‘Skywriter’ hosta should be in huge demand at full-line garden centers and hosta emporiums online.

Other Wild Gingers For Your Landscape

Posted by Hugh on January 13th, 2025

Although wild gingers, Asarum and Hexastylis species, can be found the world over, most are indigenous to the shaded woodlands of Asia, Europe, and North America. Wild gingers are members of the Aristolochiaceae (Birthwort family). Several species of Hexastylis and Asarum grow exceptionally well in the Southern Appalachian region (Zones 5b-7b). New varieties continue the marketplace.

European wild ginger (*Asarum europaeum*)

Wild gingers are frequently planted as a groundcover under trees and shady areas of a garden. They thrive in full to partial shade and usually will fail under full sun. Plant wild gingers in a humus-rich, acidic, moist, well-drained soil. This blog includes Asarum species that I have seen in my travels over the past 40 years.

Shuttleworth ginger (Asarum shuttleworthii) is a southeast U.S. native with blue / green variegated foliage and spring chocolate and purple flowers; 6 – 8 inches tall and 8 -12 inches spread; exceptional heat and humidity tolerant. var. ‘Callaway’ is a slow-growing, mat-forming version with silver mottled leaves; ‘Carolina Silver’ has slightly arrow shaped silvery-cream foliage. ‘Velvet Queen’ has larger, round, silver mottling foliage than ‘Calloway’. ‘Eco Medallion’ is a silvery selection with compact growth. (zones 5-8).

European wild ginger (Asarum europaeum) is a popular European species with glossy, leathery, dark green 3″ wide leaves; evergreen in mild winters; urn-shaped, greenish yellow 1/2″ wide flowers in late spring. (zones 4-7).

Chinese wild ginger (Asarum nobilissimum ‘Deep Throat’) produces giant, glossy, green leaves, which can reach a whopping 8″ length. Asarum ‘Deep Throat’ is slow spreading via thick rhizomes, and in good growing conditions can produce a 3′ wide patch in 10 years. In mid-spring, clumps are adorned with ginormous 4″ wide dark purple flowers, flecked with tiny yellow specks, and a wide white eye zone highlighting the dark purple socket.

Chinese ginger (Asarum splendens) ‘Quicksilver’ grows 8 inches tall and has large 6 inch-long, heart-shaped spreading habit with large silver mottled glossy foliage that are silver mottled. and spread 12- inches wide and 2-inch-wide flowers with white centers; Evergreen (zones (5b)6-9).

Chinese Wild Ginger (*Asarum splendens*)

Several Asian wild gingers have incredible black and white flowers within mottled heart-shaped foliage compared to U.S natives. Check out Panda face ginger (Asarum maximum) and cvs ‘Ling Ling’ and ‘Green Panda’ and Chinese Giant wild ginger (A. delavayi ‘Sichuan Splendor’). (zones 7b-10).

Asarum Care: Easily grown in humus-rich, slightly acidic, consistently moist, well-drained soils in part shade to full shade. May self-seed in the garden. Plants do not perform well in the hot and humid summer temperatures of the deep South. No serious insect or disease problems have been reported when plants are proper planting steps are followed. Slugs, snails and leaf gall are sometimes troublesome. Watch for rust.

Where to buy: Local garden centers are unlikely selling species of wild gingers. For the serious collector, do your homework and pay close attention to hardiness zones of wild ginger species. Plant Delights Nursery in Raleigh, NC is a choice shopping spot for collecting new species and cultivars from around the world.

*Asarum maximum* ‘Ling Ling’ at JC Raulston Arboretum in Raleigh, NC

Wild Ginger

Posted by Hugh on January 6th, 2025

Wild ginger (Asarum canadense) is a U.S. native spring wildflower which grows in rich garden and woodland soils. Wild ginger is a stemless 4-8-inch-tall plant (8 -10 inches wide) which features distinctive downy, basal, dark green foliage. Leaves are heart-shaped to kidney-shaped, and delicately veined, and up to 6 inches wide. Cup-shaped, purplish brown, 3 lobed, 1-inch-wide flowers appear in spring on short, ground-level stems. Flowers are often referred to as ‘little brown jugs”. Upon close inspection, flowers are borne singly on or near the ground and are mostly hidden within the foliage. (USDA hardiness zones 3-8).

Wild ginger is a native form of ornamental ginger in the Aristolochiaceae family that spans Canada into the U.S. This attractive groundcover is easily grown, although a bit slow spreading at the start. Do not confuse wild gingers with the “true gingers” which are aromatic plants from tropical countries and are not closely related to Asarum.

Asarum canadense exhibits poor drought tolerance. Plantings prosper in high organic matter gritty soil and under light to deep shade gardens. Once established after 1-2 years, wild ginger tolerates moderate drought. It can be propagated by underground rhizome divisions or from seeds.

Flowers appear in April or May and the smallish greenish hairy pointer flower lobes are hidden under the leaves and are of little ornamental value. Pollinators, mostly bees, are attracted to their sweet fragrance. Flowers are also self-pollinating. Ants, attracted by the oily chemical in wild ginger seed called “elaiosome”, disperse the seeds of wild ginger across the woodland floor in autumn and germinate the next spring. Leaves of wild ginger are deciduous, drop and decaying to the ground over winter.

The handsome foliage and high shade tolerance make wild gingers a great option for a woodland, shade, or rain/boggy grounds. Plant them as edging or border plants which easily naturalizes as a deciduous groundcover. This plant tolerates deer browsing, wet soils, heavy shade, and erosion.

Few, if any, disease and insect pests trouble wild ginger. Thrips, slugs and snails are occasionally bothersome.

As stated early, asarums are not related to culinary ginger (Zingiber officinale), a native of Asia; ginger root is widely used as a spice and a folk medicine. Wild ginger has a long history of medicinal and culinary use by Native Americans and early settlers of eastern North America.

2025 Perennial Plant Of The Year – Clustered Mountainmint

Posted by Hugh on January 1st, 2025

Clustered mountain mint (Pycnanthemum muticum), aka “blunt mountain mint” or “short-toothed mountain mint”, is a tough and adaptable perennial native to meadows and open woodlands across much of the eastern U.S. west to Texas. (USDA Hardiness Zones 4 – 8) (AHS Heat Zones 4 -10).

It is not a true mint (Mentha spp.) but belongs to the same family (Lamiaceae) and has similarly scented leaves. A must-have for pollinator gardens, heads of tiny white to light pink blooms attract butterflies, wasps, and bees from July to September. The inconspicuous flowers are upstaged by surrounding silver bracts, which give the illusion of frost in summer and persist for months. Clustered mountain mint has no serious disease issues, and its aromatic foliage is unpalatable to deer and rabbits.

Branched, vertical stems grow 2-3 feet tall (60-100 cm) and form a dense, weed-suppressing clump. Clustered mountain mint spreads by underground rhizomes and can be aggressive in moist conditions, though it is not invasive to the degree of true mints.

Site clustered mountainmint in an area where it can freely naturalize and mingle among other plants. Its silver sheen plays well with other flower colors and contrasts wonderfully with dark foliage.

Ideally, grow clustered mountain mint in full sun to part shade. It prefers medium to high moisture, fertile, well-drained soils, including clay soils. However, it is less tolerant of drought than most other mountain mints.

Clustered mountain mint can spread aggressively, especially in wet soils. Rhizomes are easy to control by cutting them to the desired size with a spade and pulling the shoots by hand in spring. Seed heads may be left until early spring for winter interest. Tolerates heat and drought once established. No serious pest or disease issues.

Garden Companions: black-eyed Susans (Rudbeckia spp.), bee balms (Monarda spp.), blazing stars (Liatris spp.), Joe Pye weeds (Eutrochium spp.), and native grasses such as little bluestem (Schizachyrium scoparium) and switchgrass (Panicum virgatum).

In my opinion, P. muticum grows too tall to utilize as a groundcover. Tried heading it back by ½ in mid-June; plants recovered very slowly, and flowering was mostly ineffective, and pollinators went elsewhere.

Christmas Rose

Posted by Hugh on December 22nd, 2024

Christmas roses (Helleborus niger), aka Christmas roses, are early winter flowering lenten roses. They bloom around Christmas time if winter temps are generally still mild. Based on the severity of winter temps, start of bloom date will vary considerably between H. niger and the more popular Helleborus x hybridus (H. x orientalis). (USDA hardiness zones 3- 8).

Christmas roses typically grow 8-15 inches tall and feature 2.5 to 3.0 inch wide, cup-shaped, rose-like white to light blush pink with yellow stamens. Each flower has five large showy petal-like sepals. Flowers usually appear singly on thick stems. Their palmately compound evergreen leaves are deeply lobed, waxy, and dark green with 7-9 leaflets. Leaves remain evergreen in moderate winters zone 5b and warmer). Foliage may be blotched and tattered in extremely cold wintry conditions that dip below zero and the leaves not protected by snow cover.

Christmas roses are rated as slightly more difficult to grow than H. x hybridus. They’re best grown in humus-rich, neutral to alkaline, well-drained soils and in part – full shade. Hellebores resent very dry summer soils. Set plants on sheltered locations away from cold winter winds. Plants usually take two or more years to establish. Divide plants clumps as needed or just left undisturbed. Plants may self-seed in optimum growing conditions.

Locate Christmas roses near a garden path that you frequently walk by in the winter and spring seasons. For best effect, set several plants en masse anytime from March through September. Fall-planted lenten roses may be difficult to establish. Utilize them as ground covers under trees, large shrubs or in woodland gardens, where they eventually will seed-in and naturalize. Trim away old foliage before the start of the winter blooming season.

Some local greenhouses pot them up in late summer for fall sales. Don’t delay planting as winter survival of roots and crowns depends on setting them in the garden by late October.

No serious insect or disease problems trouble Helleborus spp. Crown rot and leaf spot are occasional problems. Inspect leaves for aphids and slugs. It is also mostly deer resistant. Leaves, stems and roots of Lenten roses are poisonous to humans, dogs, cats and horses.

Select H. niger x hybrid cultivars:

‘Snowbells’ (H. niger) – semi-double pure white 2.5- to 3-inch-wide flowers.

‘Bob’s Best’ (H. x ericsmithii) – outward-facing, saucer-shaped, pink-flushed blooms.

‘Ruby Grow’ (H. x ericsmithii) – attractive pink buds that open to mid pink flowers that slowly deepen to green and deep pink tones in late winter-early spring.

‘HGC Silvermoon’ (H. x ericsmithii) – pewter foliage upright stalks of ivory white flowers in late winter.

‘Winter Moonbeam’ (H. x ericsmithii) – early white blooms fading to a soft dusky-pink.

Thermonasty – What Is It?

Posted by Hugh on December 16th, 2024

*Rhododendron catawbiense* – partial thermonasty following a series of cold TN nights in winter 2010

How cold did it get overnight? Perhaps you should check out your rhododendrons outside. The leaves of some rhododendron species (Rhododendron spp.) and Redneck Rhody (Daphniphyllum macropodum) droop down and/or curl up during really cold nights. Plant scientists believe that this reaction may be a plant’s way of reducing water loss through stomata cells on the undersides of leaves. This phenomenon is called “thermonasty” or “thermotropism”.

Rosebay rhododendron (R. maximum) also respond to thermonasty and Catawba rhododendron demonstrate a partial response. (USDA hardiness zones 6b-9). Most rhododendron species do not display this trait.

Scientists do not fully understand this plant tropism. It is thought to have something to do with leaf cell hydration. Thermonasty may also protect leaves during periods of high irradiance by sunlight. It may protect certain plants from cold temperature injury during daily thawing and re-freezing.

Essentially, the leaves are a type of natural thermometer. When temps dip below 20°F, leaf margins curl inward leaves roll up and droop. During periods of exposure to extreme cold, reducing surface area helps to protect the leaves. On most days, leaves unfurl to their full natural position the next morning if temps rise above 32 °F (0°C).

Tropisms are useful adaptations with several important benefits. Leaves that are particularly susceptible to damage from desiccating winter winds—tightly curled leaves — ensure surface area is reduced, thereby mitigating this threat. Broad leaf positioning to maximize sunlight collection during dark winter days may be a liability when it comes to snow loads. Narrow, drooping, needle-like leaves shed snow that may otherwise accumulate and break branches.

Caveat– gardeners may need to irrigate evergreen shrubs every 2-3 weeks if natural rainfall and snowfall levels are more than 60% below traditional seasonal amounts.

Russian arborvitae (Microbiota)

Posted by Hugh on December 1st, 2024

Russian arborvitae, aka Siberian cypress (Microbiota decussata), is a conifer ground cover that originates from frigid Siberia; it is exceptionally cold hardy to -40° F (USDA hardiness zones 2-7). Microbiota prospers in the cooler parts of the Mid-South (Kentucky, East Tennessee, Virginia, and Western North Carolina). Growth rate is slow to medium.

This amazing groundcover shows off its beautiful feathery green needle foliage from spring thru early fall. In fall it changes to coppery bronze in fall. It is utilized as a ground cover for banks and slopes. Microbiota takes a purple to bronze needle cast in late October and a brownish cast in winter. Spring warm-up restores its green needle color. It is more shade tolerant than and is an interesting alternative to ground cover junipers in northerly zones.

It forms a shrubby ground cover to 8-18 inches tall and may spread 10-12 feet wide. Feathery, soft-textured, scale-like (infrequently awl-shaped) foliage is arranged in flat, fan-like sprays reminiscent of arborvitae (Thuja). In appearance, it resembles the growth habit some of the horizontal junipers. Fruits are tiny, spherical, berry-like cones (to 0.25” diameter) with woody scales.

A well-drained soil is key to avoiding root rot, or plant in a dry location with a couple of hours of morning sun or light shade all day long. While exceptionally cold hardy, microbiota does not tolerate summer heat, drought, and high humidity. Alternatively, microbiota prefers good soil moisture drainage and cool temperatures, and tolerates windy exposed sites once fully established after two years. Deer and most disease and insect pests do not trouble it.

Celtic Pride® Siberian cypress is the leading microbiota cultivar selected for its uniform growth and resistance to tip dieback that plagues conventional varieties. Celtic Pride transforms areas into a lush evergreen carpet. It is intolerant to poorly drained soils, and hot and humid summers. Root rot may develop in excessively wet areas.

Microbiota is utilized as a specimen ground cover for banks and slopes, a ground cover for rock gardens, shrub borders, a costly lawn grass alternative around building and home foundations, and a shade alternative to ground cover junipers.

Although not commonly sold at local garden centers, microbiota may be purchase from online specialty nurseries in the U.S. and Canada.