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

Angel Wings (Senecio)

Posted by Hugh on September 15th, 2025

*Senecio candica*ns ‘Angel Wings’ used as a summer bedding plant

For unique foliage texture or color, look no further than Angel Wings Senecio (Senecio candicans). It is a fast-growing succulent flowering plant of the Asteraceae family that is native to South America (Patagonian region of Chile). Its big furry foliage is white and wavy.

Introduced by Concept Plants, Angel Wings works well in mixed containers or equally well in a mixed perennial border. Utilized usually as warm season annual, it favors warm temperatures between 60° – 80°F. In southern hot zones provide some morning or afternoon shade to avoid scorching its leaves. Senecio is not frost-hardy and should be protected from temperatures below 40°F. If grown in colder climates, consider moving potted plants indoors during winter. (Zones 9a -11).

Its large, soft silvery succulent leaves are soft and fuzzy to the touch. The plant grows up to 16 inches (40 cm) tall. The Angel Wings plant blooms in the summer months with a mostly insignificant small yellow flowers.

Angel Wings plants thrive in full sun, requiring at least 6 hours of direct sunlight daily. While they can tolerate partial shade, too little sunlight may result in leggy growth and a duller leaf color. If grown indoors as house plants, place them near a bright window with maximum light exposure.

Plants are drought-tolerant and prefer moderate watering. Water deeply when the top inch of soil is dry, ensuring the soil drains well to prevent root rot. During hot weather, occasional deep watering is beneficial, but overwatering should be avoided. Reduce watering frequency in cooler months.

In the garden utilize as a bold accent against green-leaved plants and colorful flowering perennials in sunny, drought tolerant borders, rock gardens, succulent gardens, and containers. Angel Wings tolerate either alkaline or acid soils and it can handle a bit of salt spray around beach areas.

Fertilize with a balanced, diluted liquid fertilizer such as Miracle Gro™ or Jack’s™ every 4-6 weeks during spring and summer. This will help your plant thrive and maintain a vibrant appearance.

Where this tender perennial is not hardy outside over winter, grow it indoors as a houseplant in a sunny window. As a summer bedding plant in a sunny area in well-drained soil. Utilize as an accent plant mixed with other summer flowering annuals where the soft velvety foliage may be touched and appreciated.

Angel Wings performs better in a container with good potting media drainage than one grown in garden soil. Protect from excess rainfall and hard frosts. For maximum appearance, pinch off dead or damaged leaves. Periodically, inspect pests like mealybugs, aphids, and spider mites. For proper pest management, use insecticidal soap or Neem oil.

American Elm Continues To Be Planted

Posted by Hugh on September 11th, 2025

Ulmus americana 'Princeton' — *Ulmus americana* ‘Princeton’ – young tree

American elm (Ulmus americana) is a medium to large deciduous tree, typically growing to 60-80 feet tall with a vase-shaped, broad-rounded crown. It is native to eastern and central North America. Once widely planted as a street and lawn tree, its populations have been decimated by Dutch elm disease (DED) over the past century. Numerous pure-bred selections are being produced at nurseries. (List of Cultivars follows).

In landscape circles, American elm is recognized as the perfect shade tree to shade a home or backyard. This native tree has the classic vase-shape branching. Although cultivars may be selected for DED-resistance, they may still be at risk for other elm diseases, such as elm yellows and verticillium wilt. DED-resistance does not mean a cultivar is immune, but specific ones have significantly improved survival rates compared to seedling elms.

Insignificant small green flowers appear in spring before the foliage emerges. Flowers give way to single-seeded wafer-like samaras (each tiny seed is surrounded by a flattened oval-rounded papery wing). Seeds mature in April-May as the leaves reach full size. Rough-textured, ovate-elliptic, dark green leaves (to 6” long) have toothed margins and asymetrical bases. Leaves typically turn an undistinguished yellow in fall.

‘Princeton’ American elm branching framework

There are dozens of named cultivars of Ulmus americana. These are hybrid pure-blood selections.

‘Princeton’ was released by the Princeton Nursery in northern New Jersey in 1922 for its resistance to DED. demonstrates excellent resistance to DED. This variety is susceptible to phloem necrosis and wetwood. It is still planted in urban streets, parks, and on residential properties.

‘New Harmony’ was discovered in Ohio in 1922 and exhibits the old American Elm form and resistance to DED. Upright, vase-shaped tree with an arching form. Dark green leaves turn yellow in fall. Vigorous growing and slightly narrower than Valley Forge.

‘Valley Forge’, introduced by the U.S. National Arboretum, has the highest known DED resistance to date. Valley Forge’ seems to be more tolerant (96% resistant rate) of Dutch elm disease compared with ‘New Harmony’ (86% resistant rate). ‘Valley Forge’ demonstrates good cold hardness as far north as zone 4a.

‘Jefferson’ is a surviving clone found growing on the National Mall in Washington DC and introduced by the National Park Service. ‘Jefferson’ has excellent resistance to Dutch elm disease. However, the cultivar is susceptible to phloem necrosis, a disease that attacks the food-conducting tissue of the tree and susceptible to a bacterial disease called “Wetwood” that results in slow tree dieback.

Colonial Spirit® is another introduction from Princeton Nursery high DED resistance and has the classic American elm vase shaped branching habit. (65 feet high x 50 feet wide).

FYI — Hybrids of European and Chinese elms are Dutch Elm-resistant are available and grow shorter than American elms.

Something New – El Niño™ Chitalpa

Posted by Hugh on September 4th, 2025

A new large shrub or small tree, called EL Niño Desert Orchid is a very special North American native hybrid. Hardy to USDA hardiness zones 6-9, it is as easy to grow as it is beautiful. El Niño produces large rose pink, orchid-looking blooms that appear in early summer.

*Chitalpa* El Niño at St. Mary’s Church Grounds in Johnson City, TN (zone 7a)

NCSU’s Dr. Ranney is credited for this new, uniquely compact introduction. In breeding terms, El Niño is an intergeneric hybrid of Desert Willow (Chilopsis linearis) and Catalpa (Catalpa bignoniodes). Both parents are in the Bignoniaceae family. Desert Willow is well-known for its tolerance to poor soils and the dry heat of the American Southwest. The tree may eventually reach 30 feet in height.

Native catalpas are large 60 foot trees that bloom annually in their native habitat that includes Tennessee and North Carolina and are mildew resistant. Catalpa’s lovely purple orchid blooms appear in early to mid-summer and sporadically through the summer months. Oh, its blooms are delightfully fragrant up close.

In its first year Chitalpa El Niño should grow 5-6 feet tall and spreading to 4-5 feet wide. El Niño forms an upright 10-15 feet mounded shrub or small tree in 10 years. An abundance of rose-pink, orchid-like flowers form on top of the new growth in mid-June. Flowering continues into very early September here in Northeast Tennessee (zone 7a).

Hardy in zones 6-9, El Niño should be grown in full sun to part sun locations (6-hour minimum) and in well-drained soil. At the colder end of its hardiness range, it may die back to the ground in a cold winter and regrow the following spring.

El Nino develops into an excellent multi-branched small tree or shrub. Pruning is rarely required, but if desired, pruning should be done in early spring. It can tolerate summer heat and poor soil conditions. Once established, Chitalpa El Niño is drought tolerant. This landscape shrub/tree thrives with a light feeding of slow-release fertilizer or seasonal irrigation if needed.

No pesticides are needed and Chitalpa El Niño is deer-proof. Landscaping with native plants promotes biodiversity and provides shelter and quality food for wildlife and pollinator.

Chitalpa El Niño should become more available at garden centers that sell Proven Winners (PW) nursery stock.

Summer Planting Combinations At Biltmore

Posted by Hugh on August 30th, 2025

On a recent visit (8/27/25) to the fabulous Biltmore Estates* Walled Garden near the Greenhouse Conservatory were some wonderful colorful plant combinations:

Yellow lantana (base), ‘Fireworks’ Pink Gomphrena, Yellow Cannas

Cupheas (base), Coneflowers, Cannas, Purple foliage Castor beans

‘Campfire’ Coleus (*Plectranthus*) in foreground and ‘Coffee Cups’ Elephant Ears (*Colocasia*) in background

*Biltmore Estates in Asheville, North Carolina

Scarlet Rose Mallow

Posted by Hugh on August 16th, 2025

Swamp hibiscus (Hibiscus coccineus), aka scarlet rose mallow, is a hardy perennial plant that grows in swamps, marches and roadside ditches in the Southeastern U.S. (USDA hardiness zones 5-9). It can grow 6 to 8 feet tall and 2 to 3 feet wide. The 5- to 6-inch-long palmate leaves are 3 – 7 lobes and have jagged teeth along their margins. Deep red flowers measure 5 to 6 inches across in mid to late summer. A white bloom form ‘White Texas Star’ is also available.

Scarlet rose mallow is a late spring starters, but their growth rate is voracious. This herbaceous to semi-woody perennial dies back in the winter and returns in late May, generally following the emergence of rose mallow (H. moscheutos). Speed of stem growth is torrid and easily achieves 5-6 feet by late July when first blooms start opening. They can grow to be over 6 feet tall and may need staking, depending on their height and position. Swamp hibiscus bloom continuously, and plentiful blooms last only 1-2 days.

Swamp hibiscus grows well in loamy well-drained soils with back-up irrigation, but is equally at home in wet boggy sites, such as pond or the edge of a stream. Set them at the back of a perennial border, against a courtyard wall, or in rain and pollinator gardens. The plant attracts butterflies, hummingbirds, and bees. Flowers are a wildlife food source. Unfortunately, deer may consume the colorful flowers.

Swamp hibiscus thrive in hot humid summers. If you garden in a northerly zone, protect plant roots and crown with a 3-4 inch layer of organic mulch (grass clippings, fallen leaves, or yard waste) in late autumn. Swamp hibiscus can easily susceptible to leaf burn if summer rainfall is low. Avoid planting on a windy site.

In spring fertilize with a 6-month slow-release formula like Osmocote™ or Nutricote™. In spring remove the previous year’s tall dead stems. Optionally, cut new spring growth back in early June (4-5 weeks after shoot emergence) to encourage branching and grow a more manageable 3-4 foot plant to summer’s end.

Plants may be damaged by stem canker, rust, leaf spots, aphids, and hibiscus sawfly. Scarlet Rose Mallow usually outgrows most injury by outgrowing these pests and still present an attractive floral show. If plants are grown in partially shade, swamp hibiscus may require staking.

Growing Rose Mallow (Hardy Hibiscus)

Posted by Hugh on August 6th, 2025

Summerific® Hibiscus are all Perennial Hibiscus, primarily tracing their parentage back to Hibiscus moscheutos. This species is native to North America, specifically the central and eastern regions of the U.S. Perennial Hibiscus are hardy from zones 4-9 and dieback to the ground each year. They produce exceptionally large flowers in an increasingly wide color range.

All varieties in the Summerific® Hibiscus collection have indeterminate blooming, meaning Summerific® varieties have top to bottom flower coverage, bloom time starts earlier with significantly more flowers over the season. Flowers are dinner plate size!

Full sun is a must. In too much shade the otherwise sturdy habits stretch and get floppy. Increased shade will also lead to a decrease in flower bud count and diminished bloom performance. Outdoor natural UV light (full sun) brings forth darker foliage colors compared to the same varieties produced in greenhouses. When properly located in full sun, Summerific® Hibiscus keep their tidy habits and bloom profusely.

‘Cherry-Choco-Latte’ -compact 4 ft. tall x 4 ft. wide; very large 8-9” flowers are white with deep pink veining and a notably large eye; dark olive-green foliage. Released in 2023.

Summer Care Tips

Summerific® Hibiscus perform best with weekly irrigation, delivering 1.5 – 2.0 inches starting 1-2 weeks prior to beginning of flowering in mid-July thru mid-September, unless Nature provides some. Also, water plants that have been recently transplanted or are aborting floral buds. Rose mallows are perfect additions to landscape areas that periodically flood and a rain garden.

Once rose mallows emerge in mid-spring, leave them adequate space to grow. Some varieties can grow 5-6 feet wide and grow quickly during the year. If you take a week’s vacation in June, you’re likely to come back to a plant twice the size you left it.

Hibiscus sawfly is the #1 foliar pest of perennial hibiscus, resulting in skeletonized leaves. These can be treated with a beneficial bacteria product like Dipel (BT bacillus). Rose mallows are not the preferred food of deer and rabbits.

‘Midnight Marvel’ – vigorous (4.0 ft. tall x 4.5 ft. wide), dark foliage, long-flower season (9″ blooms);
2012 release.

Hardy Cyclamen

Posted by Hugh on August 1st, 2025

Hardy-leaved cyclamen (*C. hederophyllum*)

Hardy cyclamens are tuberous perennial that bloom according to species. They are native to Europe, around the Mediterranean region and parts of Asia and Africa. Two popular hardy species in U.S. gardens are spring-blooming Cyclamen coum and fall-flowering ivy-leaf Cyclamen hederifolium. Leaves remain evergreen through much of the winter season. Non-hardy florist cyclamens (C. persicum) are available at florist shoppes in floral shades of whites, pinks, and magentas along with beautiful mint green and silver mottled foliage.

C. coum emerge from summer dormancy in October thru March and reenter dormancy in mid-spring as outdoor temps warm up. Leaves are round- to heart-shaped, with smooth or slightly toothed margins, from plain green through varying degrees of patterning in grey or silver to all over silver, underside purplish. At least a dozen more species are hardy in zones 7-9. C. hederifolium is dormant during the hot dry summers and fridge cold winters. Long-lived cyclamen often provides years of reliable color and interest with their handsome foliage.

Hardy cyclamens prefer part to dappled shade and do not cope with sunny locales. Instead, plants are best at home under the dappled shade of large shrubs or trees. Plants colonize in humus-rich, well-drained soil. They’re actually a good choice for dry shade. and will fail in daily summer irrigation.

*Cyclamen coum* (winter-spring blooming)

Site selection is very important. Choose a spot in part to full shade, with dappled sunlight okay. Hardy cyclamens grow from small, roundish, flattened tubers, which should be planted shallow (about an inch deep) in late summer into fall. Again, summer dormancy should be dry. Fertilizing cyclamen is unnecessary. Apply fine compost and organic mulches at planting time and annually in late spring to improve soil texture and bed appearance.

After blooming, cyclamen plants self-sow their tiny seeds forming new tubers; tubers also grow in size through the years. Mark the spot where you’ve planted them so not to disturb them when they go dormant each summer. Keep the area weed-free where the cyclamen are planted. Divide tubers during the summer dormancy period. Every 4-5 years, lift each tuber, divide with a clean sharp knife, and replant.

Hardy cyclamens are rarely troubled by disease and insect pests. Squirrels and rodents may dig up tubers and may require DIY wire cages for protection. Keep house pets away from cyclamen.

Hardy cyclamen may be ordering through the summer into early fall from online bulb nurseries which ship in late September and early October. Plants are also available potted up in late winter and early spring from nurseries and gardening shows. They’re rarely sold at garden shoppes.

Chartreuse In Summer Shade – ‘Sun King’ Aralia

Posted by Hugh on July 28th, 2025

‘Sun King’ Aralia at Franklin Park Conservatory in Columbus OH (June 2025)

Plants with golden foliage can brighten up almost any drab garden patch. Sun King golden aralia (Aralia cordata ‘Sun King’), called Japanese spikenard and mountain asparagus, is no exception (USDA hardiness zones 3-9). Under ideal conditions this thornless, rhizomatous, herbaceous perennial starts out slowly to reach 3-5 feet tall and wide in its third summer.

‘Sun King’ emerges in mid-spring with bright gold compound foliage (each leaflet to 6 inches long); foliage color slightly fades to chartreuse through the summer in moist humus-rich soil. Seasonal growth rate is slow at first and dies back to the ground in late autumn. In mid-summer numerous small clusters of tiny white flowers shoot up, borne on 2 feet tall racemes. Flowers add very little in ornamental value. After blooming, the tiny white flowers produce deep purple-black, inedible berries.

Sun King aralia makes a bold almost tropical statement in a semi-shade garden alongside variegated Solomon seals, hostas, brunneras, lungworts, bergenias, coral bells, and astilbes. It is a slow starter… The phrase “first year it sleeps, second year it creeps” fits Sun King to a tee. Grow it in a compost-rich moist soil and in ½-day sunlight (morning hours preferred).

Golden aralia creates an impressive focal point; group multiple plants for a dynamic show in large landscapes. It should be kept mulched. Irrigate to keep foliage lush during a dry spell. In USDA zones 8 and 9, grow only in dappled sunlight to avoid foliage burn.

Sun King aralia mixes well in large containers planted with green and other brightly colored foliage plants. Golden aralia is deer resistant, and the tiny white flowers attract numerous honeybees.

Clusters of purple berry fruits form in October

A native of Japan, Korea, and China, ‘Sun King’ aralia was introduced into the U.S. by Barry Yinger. Sun King was designated the Perennial Plant of The Year in 2020.

Caution: Birds love the tiny berries, which are NOT edible for humans.

Native Hypericums

Posted by Hugh on July 17th, 2025

St. John’s Wort (Hypericum spp.) is a genus of about 400 species of annuals, perennials or shrubs which are noted for producing showy bright yellow flowers with a central mass of bright yellow stamens. Hordes of bee species love hypericum flowers. In midsummer, this U.S. native produces yellow flowers with distinctive clusters of puffball of stamens followed by colorful berries in fall (Hardiness zones 4 – 8).

Four North American native species are singled out here with slender clusters of fragrant white early summer. Also containing brilliant red-purple fall foliage color that lasts into winter.

Golden St. John’s Wort (H. frondosum): ‘Sunburst’ is the most popular hypericum in U.S. gardens because of large bright yellow 3-inch-wide flowers and lovely blue green foliage. Dense, blue-tinged, green foliage on a compact, upright shrub that is excellent as a foundation plant, in mass plantings, and informal hedges. Vivid yellow flowers with a distinctive puffball of stamens add sunny color to the summer landscape. Seldom grazed by rabbits or deer. (USDA zones 5-8).

Kalm St. John’s Wort (H. kalmianum): – a low-growing shrub that produces yellow flowers and blue-green foliage. In its northern areas where it is indigenous, it is called “goatweed”. Klamath produces dainty yellow flowers that grows in full to partial sun and prospers in a wide variety of soils and pH levels; exceptionally winter hardy (USDA zones 3-7).

Shrubby St. John’s Wort (Hypericum prolificum) is a compact, deciduous, rounded shrub with an erect habit that typically grows 2-4 feet (less frequently to 5 feet tall. Features 5-petaled, bright yellow flowers (up to 1.5 inches in diameter) with numerous, yellow stamens. Stamens are bushy to the point of partially obscuring the petals, hence the species name of prolificum for many stamens. Winter bark is shaggy and a bit unique.

Bushy St. John’s Wort (H. densiflora) is a native shrub growing up to 7 feet tall / 3-5 feet wide. Leaves are 2–3-inch lance-shaped and green. This native species performs exceptionally well in moist acidic soils in moist and wet conditions in eastern USA and west to Texas. It excels in sopping sites including streams, ponds, and wet meadows. Clusters of yellow flowers attract butterflies in summer. (USDA zones 5-8).

Hypericums are generally untroubled by disease and insect problems when shrubs are properly sited. Pruning is minimal, primarily to hold the species to its place in the garden. Native species are difficult to find at local garden centers. Check out online native plant sellers.

Firecracker Plant (Cuphea)

Posted by Hugh on July 10th, 2025

Planting Cupheas should set off fireworks in your summer flower garden. Cupheas are dependable, low-maintenance flowers that easily cope with the heat and humidity of the South. They’re exceptionally long blooming, attract bees, wasps, butterflies and hummingbirds like magnets, and are versatile enough for container plantings or in-ground beds. (See list below).

Currently, the most popular of the cupheas is Vermillionaire® Firecracker Plant (Cuphea x ‘Vermillionaire’), sometimes called “cigar plant”. It ignites multi-seasonal color and are really catching on with gardeners. Around the latter days of spring, scarlet-red tubular flowers with burnt tips emerge in abundance at the leaf axils along the stem.

Grow cupheas in full day sun (6 or more sun and in well-drained, fertile soil. Plants are moderately drought-tolerant, but prefers regular, light watering. Moderately fertilize with slow-release fertilizer at planting time.

Cuphea plants prefer fertile, light, well-drained soil. While fertilizers aren’t necessary, amending the soil with organic matter can help produce abundant blooms. Also, plant cupheas in raised beds or containers for improved drainage and aeration. Irrigate during prolonged summer dry spells.

Most cuphea plants are moderately drought-tolerant once established. However, these shallow-rooted species typically produce the most vigorous growth and abundant blooms when the soil remains evenly moist during the growing season.

Cupheas excel where summer heat and humidity soars. At the end of the autumn season, plants become frost-tough into the low 20’s and die back. Some varieties like Vermillionaire® may survive a mild winter. In zones 7b and higher, protect surface roots by mulching and/or move plants to a sheltered site to improve survival levels.

Plants need only moderate fertilizing levels from spring through summer and no more. Plant cupheas in humus-rich soil One time application of a slow-release fertilizer at the start of the growing season is adequate OR monthly feedings with a water-soluble fertilizer like Miracle-Gro™.

Worldwide there are over 250 cuphea species and many more cultivars and hybrids. Most popular in U.S. gardens include:

Cigar plant (C. ignea) is a tender, low-growing annual; burgundy red blooms put on a show from late spring to fall. (zones 10 – 12).
Vermillionaire® Firecracker Plant is popular cuphea hybrid from PW with showy, long blooming, fiery, tubular orange to red flowers; it grows 2.0 – 2.5 feet high and wide and may overwinter in a mild zone 7 garden with a leafy mulch cover. (zones 8 -11).
Starfire cuphea (C. ignea x C. angustifolia) grows 18-24 inches high and two-thirds that in width with multi-colored pinkish-red, white and violet flowers.
Honeybells® – rose and light-yellow, ground hugging hybrid; grows 8-10 inches tall.
Hummingbird Lunch® (C. ignea) – bi-color blooms (red with yellow tips); 2 feet tall x 3 feet wide.
Batface cuphea (C. llavea) flowers resemble the face of a mouse, with two red petals tinged in purple. Batface is a bee magnet on a sunny fall day.
Mexican heather (C. hyssopifolia) is a compact 16–24-inch annual that stands out for the purple or white flowers. Reaches up to two feet tall. (zones 9-11).
Candy corn (C. micropetala) grows 2.5 – 3.0 feet high annual with yellow to orange tubular flowers. (zones 8-11).

Cuphea plants are beloved for their long flowering season. Many bloom continuously from the warm days of late spring to the first hard frost of autumn. Some cuphea species have a light, pleasant fragrance, while others are unscented.

Cuphea are relatively disease- and pest- free and deer resistant. Wet soggy soils will weaken plants. Occasionally, aphids, thrips and whiteflies may be possible but are simply eliminated by applying insecticidal soaps or neem oil.

Mexican heather (*C. hyssopifoli*a) pink blooms in container at Yew Dell Botanical Gardens, Crestwood, KY

Optional info: to prevent plants becoming tall and leggy, pinch stem tips during in late May or June. In Southern climes cutback leggy perennial cupheas to a few inches from the ground or container in late winter or early spring to jump start new spring growth.