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

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.

Winter-blooming Snowdrops

Posted by Hugh on November 26th, 2024

Window box planting containing snowdrops at Brandywine Cottage outside Philadelphia, PA

Snowdrop (Galanthus spp.) are grown in both cold and moderate winters. In the U.S. snowdrops thrive where winters are cool (USDA hardiness zones 3-8). There are about 19 species of Galanthus – in the amaryllis family (Amaryllidaceae). They’re native to the cool woodland and mountainous regions of southern Europe and Asia Minor. They tend to struggle in warm climes in the U.S. like south Texas and southern California.

Snowdrops are among the first spring flowers to bloom, often around mid-February into early March. Purchase bulbs in fall and plant immediately after you receive them. Do not buy the bulbs too far ahead of time as they may dry out and lose viability. Space bulbs 3 – 4 inches apart. These tiny plants require very little maintenance. Snowdrops grow in a variety of garden spots.

Plant snowdrop bulbs 2-3 inches deep in soil that is prepared and ready for planting. Set bulbs with the thin end (tip) facing up. Feed with any commercially labelled bulb fertilizer to get the snowdrops off to good start. Each year in late fall, spreading 1-2 inches of well-refined organic mulch or compost should provide nutritional support to the snowdrop bed.

Snowdrops are a collector’s dream. Try some of these favorites:

G. elwesii – “giant snowdrop” and grows to be twice as tall as G. nivalis.
G. nivalis ‘Flore Pleno’ produces double flowers.
G. nivalis ‘Sam Arnott’ – large flowered, vigorous and fragrant.
G. nivalis ‘Viridi-Apice‘ has prominent green blotch on its petals.
G. ‘White Dream’ has a white stripe on leaves.
G. woronowii – “green snowdrop” – broad green leaves and little green mark on inner floral tepals.

Numerous other cultivars are listed. One authority lists over 500 cultivars – most primarily available in Europe. Snowdrops can be mixed with other early blooming bulbous beauties such as Glory-of-the-snow (Chionodoxa), Winter aconite (Eranthis hyemalis), and Crocus (Crocus spp.).

Snowdrops prefer full sun (at least 6 or more hours of direct sunlight daily). Grow snowdrops in a loose, well-drained soil with lots of humus added. They don’t thrive in heavy clay soil. Once snowdrops have finished blooming, allow the foliage to yellow naturally and wither away.

Snowdrops come up every year, and multiply and spread over time; in fact, they are easy to naturalize. Every few years lift and divide the bulbs when you wish to propagate snowdrops.

Snowdrops are disease, insect and deer resistant, and critter-proof. They are toxic to animals and humans; keep pets and children away.

Snowdrop collectors, called “galanthophiles”, attend winter snowdrop meetings to buy new plant variants and other minor bulbs. Snowdrops and many minor bulbs are hard to find at garden shops. Brent and Becky’s Bulbs, an online

Snowdrop collectors, called “galanthophiles”, attend winter snowdrop meetings to buy new snowdrop variants and other minor bulbs. Snowdrops and other minor bulbs are hard to find at garden shops. Brent and Becky’s Bulbs, an online bulb emporium in Gloucester VA, is a personal favorite.

Summer Snowflakes (Leucojum)

Posted by Hugh on November 21st, 2024

Summer snowflakes originate from Europe and northern Africa and are carefree spring-blooming bulbs. They belong to the Amaryllis (Amaryllidaceae) botanical family and are critter proof. (USDA hardiness zones 4-8). Flowers and foliage are similar to snowdrops, but snowflakes grow twice as tall and bloom about 2-3 months later, usually just after most daffodils. Pure white, nodding, bell-shaped flowers are decorated with lime green spots. Blooms dangle in clusters from arching stems. Bulbs are reliably perennial and bloom reliably every spring for years to come.

Don’t be mistaken by its common name “Summer Snowflake”. They flower in mid-spring (April into early May) and bloom over 2-3 weeks. Summer Snowflakes (Leucojum) look a lot like snowdrops (Galanthus) which grow a lot smaller and bloom in mid to late winter. Whereas the three outer petals of Galanthus are larger than the three inner petals, all six floral petals in the Leucojum genus are the same length.

A flowering stem of summer snowflake is likely to bear more flowers—up to 6 or 7 per plant. Fewer than 2-3 flowers appear on a flowering stem, is an indication that plants are not receiving adequate sunlight. Primary snowflake species are:

L. vernum, a plant of about the same size as the giant snowdrop (1 foot tall), is called the “spring snowflake.” It blooms in mid-spring.
L. aestivum is similar in size to L. vernum, but blooms slightly later in mid-spring.

Leucojum naturalized with Green and Gold (*Chrysogonum virginianum)*

Plant the bulbs 5 – 6 inches deep and 5 – 6 inches apart on center. Design for a natural look by planting snowflakes along a woodland path or a rock garden in groups of 10 or more bulbs. Give them at least half-day sun and they flower at their best under limbed up small trees or large shrubs. Let the foliage remain to rebuild the bulbs before summer dormancy sets in.

Snowflakes adapt well to most soil types and bulbs are soil pH insensitive. Bulbs require moisture during the early growth season and are moderately drought tolerant during their summer dormancy period.