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

Growing Tropical Hibiscus

Posted by Hugh on July 8th, 2025

Tropical hibiscus in front of restaurant

Tropical Hibiscus(es) (Hibiscus rosa-sinensis) are a non-hardy group from southeast Asia. They require temperatures above 50°F year-round (USDA Plant Hardiness Zones 9–12) and will likely be injured at temps below 35°F. They are evergreen cousins of the very hardy deciduous shrub group —Althea (H. syriacus) and herbaceous perennial favorites like Rose Mallow (H. moscheutos) and Scarlet rose mallow (H. coccineus).

Tropical hibiscus are often purchased at garden shops as patio, deck, or house plants. To repeat, plants are not frost tolerant. Their magnificent blooms last 1, maybe 2 days, and in an awesome range of color shades and sizes. Flower widths range from 2-10 inches across. Single or double flowers are available. In southern states or in greenhouses, some grow into large landscape shrubs, 4-10 feet tall and 3-6 feet wide.

Tropical Hibiscus can be grown in containers and offer a tropical environment on a deck, patio or around a pool. Tropical hibiscus are sun-lovers, e.g. they prefer moderate to full day sun, but do tolerate light shade. Less light translates to fewer and/or smaller flowers. When bought into the home to overwinter, set plants near a south- or west-facing window.

Plants prefer an evenly moist root ball; do not allow hibiscuses dry out After planting in the ground, provide supplemental irrigation the first year as needed until the plant is well established. Do NOT overwater. When potting, choose a container that is sized to the plant. Check your plant every few days. Over time, you will determine its water requirements and make adjustments according to how much sun or rain it is receiving.

In northern zones plants should be overwintered indoors in a South- or West-facing window. Hibiscus require less water during the cooler months. Scout for pests and diseases before bringing them inside and treat as needed. Prune through fall-winter to hold a desired shape. Before plants go outdoors in the spring, give branches a hard cutback.

Slow-release fertilizers are an easy way to keep plants fed throughout the growing season. Another feeding alternative is to feed with a complete fertilizer containing high phosphorus to encourage sturdier stems and more flower numbers. Select a fertilizer designated for tropical plants that contains supplemental iron to avoid chlorotic (yellowed) foliage. Feed plants from April through October and reduce feeding by one-half.

At Biltmore Estates in Asheville, NC in summer. Plants are grown inside Conservatory in fall-winter months

Unfortunately, plants are susceptible to a number of sap-feeding insects. Inspect leaves and stems for aphids, thrips, spider mites, whitefly, scale, and mealybug. Look particularly the undersides and spray with horticultural oil or insecticidal soap. Alternatively, prune out infected stems if outbreaks are severe. A few potential disease problems are powdery or downy mildew and botrytis. Black spots are often seen as well but their causes are vast and hard to identify without proper testing.

Occasionally floral buds or leaves do not open, turn yellow and drop off. Climatic issues, overwatering and drought stress may be the cause. Roots injury may be a cause. Contact your county/state Extension office for proper identification and treatment of plant maladies.

Tall Growing Daylilies

Posted by Hugh on July 1st, 2025

*Hemerocallis* x ‘Citrina’ -nocturnal bloom

Tall daylilies (Hemerocallis altissima) are a group of late season fragrant daylilies that are native to southwest China, singled out for their tall 5-6 feet floral spikes. Blooms open in late afternoon and are classified as “nocturnal bloomers”. In spring, this deciduous perennial starts out with 2-feet tall grass-like foliage. In summer they produce tall flower spikes 4 – 6 feet tall and 1 – 2 feet wide, adorned with fragrant, pure yellow flowers. Yellow shades of flowers open approximately 4-8 p.m. and remain open thru the next morning. (USDA hardiness zones 3-9).

Daylilies thrive with full sun all day long yet bloom satisfactorily with 6 hours of full sun. Clumps tolerate a wide range of soil types and conditions including briefly soggy soil. Altissima daylilies handle short dry spells lasting 10-14 days, but they perform poorly on chronically dry sites.

The floral display of H. altissima are big, bold and bright. Rate these late bloomers as season extenders. Most daylily cultivars, including rebloomers, flower over many weeks from June into mid-July and rebloomers return in mid-September into October. Night blooming H. altissima daylilies offer additional excitement to the evening garden. Plant where they can be enjoyed in the evening such as a patio or a window.

As a rule, tall daylilies are low maintenance. After flowering ends, snip off the spent bloom stalks and crop off some grassy growth. Lightly fertilize as fresh new foliage emerges in late summer. Irrigate as needed. After a hard frost, mow off daylily foliage at 4–5-inch setting. Fall/winter clean up takes only a few minutes per plant.

Easy care is the rule. H. altissima grow in a wide range of soils. Plant in garden beds along walkways and around patios or in containers where you may enjoy their tall flowers and their evening fragrance. Daylily petals are edible and great in salads. Pollinator attractors include hummingbirds, butterflies, and bees. Inspect spring and summer foliage for aphids. Unfortunately, deer also enjoy their blooms and foliage. Stake some varieties that sometimes flop under the weight of flowers @ 25-30 buds per stem.

‘Notify Ground Crew’ (Curt Hanson introduction) at Longwood Gardens

Hemerocallis altissima, syn. var. citrina, is a little-known, fragrant daylily species native to southwest China, characterized by its tall floral spikes and nocturnal blooming habits.

Leading Varieties:

‘Autumn Minaret’ – (A.B. Stout introduction) – fragrant, 4.5-inch-wide yellow flowers with a dark peachy “eye” inner throat; 75-inch-tall bloom scape (late season bloomer)

‘Challenger’ – (A.B. Stout introduction) – fragrant, 5-inch-wide brick red with a golden heart and creamy-yellow midribs; 54-inch-tall bloom scape.

‘Notify Ground Crew’, (Curt Hanson introduction) – fragrant, 5-inch-wide yellow blooms (tetraploid), well-branched floral scapes over 6 feet tall; well branched, open after 4 p.m. daily.

H. citrina var. ‘Citrina’ – 4-inch-wide lemon yellow flowers on 4-5 feet tall stalks; June-July bloomer opens after 6 p.m. daily

Gauras For Summer Flower Power

Posted by Hugh on June 24th, 2025

Lots of TN, VA, and KY gardeners don’t know Gauras, a tough beautiful Texas native perennial that performs equally well in our area. After countless trips to Biltmore Estates and the NC Arboretum in Asheville, I have gained an appreciation for its long summer blooming habit.

Gaura (Oenothera lindheimeri) is a low-maintenance perennial native to the southern U.S. (Zones 5-9). Gaura is often called “whirling butterflies”, “wandflower”, and “beeblossom” because the flowers appear to dance in the breeze. Gaura blooms all summer long producing graceful wands of nectar-rich white, pink, or bi-colored flowers that butterflies love.

Botanists have recently moved Gauras into the genus Oenothera, which also includes evening primrose (Oenothera biennis), and its official botanical name is now Oenothera lindheimeri.

The rabbit/deer resistant plants grow 2-3 feet tall. White flowering varieties have small, mostly non-distinctive green leaves. Modern dark pink flowering varieties flaunt foliage with deep reddish tones.

Site selection and ground prep are highly important in growing gauras. Otherwise, gauras are generally not long-lived perennials. Best flowering performance seems to be full day sunlight in the Mid-South region. Soil drainage is key. Wet, soggy winter soil will limit its garden longevity. Amend the soil deeply with a mix of compost and gritty sand (not beach sand) or in raised beds. Plants have a long deep taproot and are nearly impossible to transplant.

Plant 3-5 gaura plants for better visual impact and space them at least 18-24 inches apart. Dwarf varieties are also excellent container plants. Irrigate sparingly to encourage this taproot plant to dig deep. Generally, gaura thrives in poor lean soil and does not require fertilizing. Too much fertilizer can make plant(s) floppy.

Five Beautiful Gaura (Wandflower) Varieties:

‘Corrie’s Gold’: Flowers are white tinged with pink and gold variegated foliage.
‘Passionate Rainbow’: pink flower wands and pink-edged foliage.
‘Siskiyou Pink’: showy rose-pink flowers on its notably wispy stems.
‘Sparkle White’: dainty white flowers are tinged with pink.
‘Rosy Jane’: compact, 18-24 inches high and wide, eye-catching performer that produces masses of white flowers with a pink picotee edge.

Overall, gauras may be affected by certain pests like aphids, whitefly and flea beetles. Root rot may occur in heavy and/or poorly drained soils. Rust and powdery mildew outbreaks may pop up in wet summers. To promote compact growth with abundant flowers, fertilize sparingly. Applications of insecticidal soap should resolve most pest issues.

Gaura plants tend to flop over in a shady garden, and staking may be necessary. Flowers invite pollinators by the score. Shop for dwarf gaura varieties to use in containers

After the first hard frost in the fall, or after flowering has ended, cut back all stems and foliage to ground and clean away debris to prevent pests from overwintering.

Fertile Lacecap Smooth Hydrangeas

Posted by Hugh on June 18th, 2025

Smooth hydrangea or wild hydrangea (Hydrangea arborescens) is an open widely branched deciduous shrub that typically grows to 3-6 feet. Tree forms frequently grow to 10-20 feet and higher over 25 years or more. This U.S. native hydrangea is indigenous from New York to Florida and west to Iowa, Missouri, Oklahoma and Louisiana. (USDA hardiness zones 4-9).

*H. arborescens* ‘Haas Halo’ in June Garden

Smooth hydrangeas perform best in morning sun and afternoon shade or dappled day-long sunlight Plants tolerate full sun if planted in good well-drained soil and provided supplemental water during drought periods lasting 10 days or more. Annual spring mulching is highly recommended.

Seasonal foliage is sharply toothed and dark 2-6-inch-long green leaves with pale green undersides; leaves turn yellow in fall. Tiny white fertile flowers bloom in May-July on flattened hairy clusters (corymbs to 2-6 inches across). Scattered continuing flowering may occur through summer months. A few large sterile flowers usually appear at the cluster margins, usually not enough to spoil their flattened lacecap shape. Flowers give way to dehiscent seed capsules which ripen in October-November.

Fertile Lacecaps hydrangeas are called “Dome Hydrangeas”. Invincibelle Lace^®, ‘Hayes Starburst’, ‘Haas’ Halo’, and ‘Dardom’ are unaffected by winter cold and late spring frost and bloom on new growth.

Invincibelle Lace^® hydrangea produces plum purple florets on strong ruby red stems incredible in informal style gardens, providing year-round interest. Its elegant coloring and graceful habit fit in perfectly with gardens. It is also a pollinators’ delight and is incredibly winter hardy (zones 3-8).

White Dome® (‘Dardom’) at MT Cuba Center (September)

‘Dardom’ (commonly sold under the trade name of WHITE DOME), is a patented cultivar that originated in 1997 from a chance pollination of two unidentified selections of H. arborescens. It is a large, upright, freely-branching, rounded shrub with strong stems that is distinguished by its vigorous growth, large leaves and large dome-shaped inflorescences of white flowers. It typically grows 3-5 feet tall. Mostly fertile flowers with a sprinkling of sterile flowers appear in huge, symmetrical, rounded heads (corymbs resembling white domes) which typically grow 6-10 inches across. Flowers bloom in early June for up to two months. Flowers contrast well with the ovate to elliptic, serrate, dark green leaves (3-8 inches long).

Winter floral seedhead of White Dome® (‘Dardom’) at Biltmore Estates, Asheville, NC

‘Mary Nell’ hydrangea (Hydrangea arborescens ‘Mary Nell’) is underutilized and deserves to be planted more widely. It was named by Dr. Joseph McDaniel, who also introduced H. arborescens ‘Annabelle’. ‘Mary Nell’ is a lacecap hydrangea that stands out, with a double ring of sterile flowers around the rim of the inflorescence. Comparable in overall size to ‘Haas’ Halo’. ‘Mary Nell’ produces slightly smaller flower heads with more sterile flowers at the margin. ‘Mary Nell’ performed best in shade, retaining attractive foliage and sterile flowers for nearly the entire growing season. With exceptional plant vigor but stems occasionally proved to be too weak to support the magnified flower heads.

Many species of hydrangea, including this one, are susceptible to bud blight, bacterial wilt, leaf spots, mold, rust and powdery mildew. Watch for aphids, mites, scale and nematodes. Pruning stems back to the ground in late winter each year helps promote stem vigor. Rabbits tend to avoid this plant. Unfortunately, deer generally love to munch on hydrangea flowers and foliage.

Further Reading: MT. Cuba Center Plant Evaluation – Hydrangea arborescens

Tall Stewartia

Posted by Hugh on June 10th, 2025

Tall Stewartia (Stewartia monadelpha) is a deciduous flowering shrub or multi-trunked small tree that grows 20-25 feet tall with a pyramidal framework when young. As the tree ages, horizontal branches open up more. Tall Stewartia is a native of Japan and is indigenous to cool mountain forests. Stewartias are members of the Theaceae botanical family which include Camellia, Franklinia, et.al. (USDA hardiness zones 6b – 8b).

Late May flowers (in Tennessee) on *S. monadelpha*

Low maintenance tall stewartia performs best in partial shade, preferably early morning to early afternoon. Either avoid hot mid-afternoon sun or routinely irrigate during spring/summer dry periods. Once established in 2 years, tall stewartia exhibits above average heat and drought tolerance. Site the tree in well-drained, humus-rich, acidic, loamy or sandy soils. Mulching with shredded pine bark is advised.

Tall Stewartia is identified by its smooth orange-bark which gets better and better as the tree ages. The main and scaffold bark chips off in thin exfoliating sheets. Small white camellia-like flowers appear in late spring in Tennessee. Its autumn scarlet red foliage is an added plus.

Dark green elliptic leaves, 1.5 to 3 inches long, have finely serrated margins and grayish-green beneath. Fall foliage is orangey-red to deep scarlet and intensity tends to be variable from one year to another. The white cupped-shaped flowers measure 1 to 1.5 inches wide and have yellow-orangish stamens. The five-segmented small oval hard fruits (capsules) ripen in the fall.

Tall stewartia is heat and drought tolerance make this plant an ideal small landscape tree in Mid-Atlantic and Mid-South states. Consider Tall Stewartia for a shrub border, patio area, accent, lawn specimen, or street tree.

Smooth tan patchy bark of tall stewartia at Biltmore Estates in Asheville, NC

Extra: Tall stewartia is available from on-line nursery sources. This fine landscape tree deserves more use in U.S. landscapes. It has no serious insect or disease issues. Pollinators enjoy our multi-year landscape tree in Northeast Tennessee. Methods of propagation include seeds or stem cuttings.

Vincas/Annual Periwinkle Thrive In Hot Summer Gardens

Posted by Hugh on May 26th, 2025

Annual vinca or periwinkle (Catharanthus roseus), aka Madagascar vincas, is a summer flowering annual popular in Southern and Midwest gardens (USDA hardiness zones 9-11). Before setting out spring transplants, wait until soils have warmed up and all threats of frost have passed. The arrival of summer heat and humidity is when vincas bloom heaviest. Vincas sparkle in containers, in flower beds, or in front borders around home and downtown buildings.

Vincas grow best in well-drained, humus-rich, loamy soil and in full or part sun. Fertilize at planting and a follow-up application in late July. Spring-planted vincas are usually established after 4 to 5 weeks and moderately drought tolerant. Vincas enjoy occasional watering during dry spells lasting 7-10 days. Overhead irrigation should be avoided.

Most modern-day cultivars grow short and compact. They vary from 6 to 18 inches in height and spread. An individual flower is composed of five flattened petals attached to a tubular base. A wide range of flower colors include lavender, red, rose, salmon, several shades of pink, and white. Some cultivars exhibit a center floral eye. Old blooms are self-cleaning and rarely messy. The 1-2-inch leaves are dark green and glossy.

The foliage is glossy dark green. Depending on the variety, fast-growing vinca is 6 to 18 inches tall with a similar spread depending on variety. Annual vinca plants bear single blooms with five petals that frequently touch or overlap from early summer until the first frost. Many varieties feature a contrasting eye. Most vincas stand upright, but low cascading varieties are also available. Modern-day vincas have an expanded color palette that includes pink, rose, and lilac shades.

New cultivars contract few, if any, serious insect or disease problems. More stress-tolerant due to hybrid vigor – tolerates heat and drought and can withstand cooler and wetter conditions compared to O.P. types. Plant vincas on an open site with good air circulation to prevent stem and root rot diseases (Phytophthora) and bacterial leaf spots. Aphids, spider mites, or powdery mildew can occur. Slugs and snails are occasional pests in wet summers.

Flowers are attractive to butterflies and are rabbit-resistant. Vincas often self-seed and re-appear in garden beds several future years. All parts of the annual vinca plant are toxic to dogs, cats, and people.

Cultivar Update: newest cultivars are faster to bloom, have superior branching, and bigger flowers. Popular vinca series are highly XDR resistant that protects against specific strains of Phytophthora soil disease. They include ‘Titan™, Cora™, Pacifica™ and Cora Cascade™. New Titan-ium™ series offers extra protection of aerial Phytophthora resistance and will be available in 2025. It grows 14-16 inches tall and will be available in 7 color choices 14-16 inches tall. Soiree Kawaii® series grow 6-8 inches high and 12-18 inches wide and flowers come in 8 colors (pink, coral, lavender-purple, red shades, white with red eyes).

Wild Indigo (Hybrid Baptisias)

Posted by Hugh on May 19th, 2025

Wild indigo, false indigo, or Baptisia (Baptisia spp.) is a long-lived U.S. native perennial (USDA hardiness zones 4-9). Plants are deeply tap-rooted and will reward you for many years of multi-seasonal beauty. They’re sometimes mistaken for Carolina lupine (Thermopsis caroliniana).

Baptisia x ‘Purple Smoke’ growing at MT. Cuba Center in Hockessin, Delaware

Modern day cultivars are hybrids of 8 Baptisia species. Top four species are purple (B. australis), lavender blue (B. minor), white (B. alba), bright yellow (B. sphaerocarpa). Several bicolors are also available. Baptisias are in the Pea family (Fabaceae). Long-blooming baptisias last for 3 to 4 weeks in the spring garden. Their blue-gray foliage and sturdy upright shrubby habit are pluses in the summer garden.

Baptisia x ‘Cherries Jubilee’ bi-color (Walters Gardens photo)

Long-lived baptisias perform at their best in full sun. In the shade they bloom less and stems are weak and frequently require staking. Tough deep-rooted wild indigos do not like their soils disturbed. Baptisias prefer a deep humus-rich well-drained soil but tolerate most average soils. Mulch with organic matter to keep the soil cool and weed-free.

Vigorous plants grow 3 to 4 feet high and 4 to 5 feet wide after 3 to 5 years. Do not overcrowd. Newly planted baptisias should be watered until established, usually within 1-2 year. Plants are slow to establish and begin blooming with only a few flowers in their first year and are heavily flowered within 3 to 4 years.

In early spring add 1-2 handfuls of a slow-release fertilizer around new plants. Older well-established plants require little to no fertilizer as they produce their own nitrogen. Yellowing of leaves in the summer is a symptom of iron deficiency or high soil pH. In such cases, feed with chelated iron or an acid-based fertilizer like Schultz™ or Miracid™. Established plants are heat and drought tolerant and are almost invincible to disease and insect problems.

Stunning stalks of colorful pea-like, non-fragrant flowers appear in mid-spring. Cut blooms last 3-4 days indoors. Flowers stalks give way to black seedpods by late July. Black capped chickadee, finches, and sparrows will feed on seeds. Gardeners may opt to remove the seed pods before they mature. Flower arrangers utilize the ripe blacken seedpods in arrangements.

*Baptisia* x ‘Lemon Meringue’ (photo from Walter Gardens)

Cultivars with the deeper shades of blue and yellow blooms stand out in a garden. Popular cultivars from North Carolina sources and Chicago Botanical Garden breeders include: ‘Purple Smoke’ (lavender flowers), ‘Solar Flare’ (yellow), ‘Alba’ (white), and ‘Twilight Prairie Blues’. Walters Gardens in Michigan developed the Decadence™ Series which are pictured above.

Further reading: view the MT. Cuba Baptisia Trial Report

Growing Ajuga

Posted by Hugh on May 12th, 2025

If you’re looking for an attractive perennial groundcover to quickly fill in small or large patches in your garden, you can’t go wrong with ajuga (Ajuga reptans), also called as carpet bugleweed. This creeping evergreen plant spreads quickly and thickly. Plant it on moderate slopes for erosion control. A vigorous clump should smother out weeds and add exceptional foliage color. (Zones 4-9).

Ajuga ground cover spreads through runners, and as a member of the mint family (Lamiaceae). Plants can become weedy without a little bit attention. Location and variety are key to growth and mat-forming trait can provide instant coverage with only a few plants. Bugleweeds are highly deer resistant.

Ajuga flowers are normally blue to purple but white blooming forms are also available. Over the past two decades, there has been an explosion of new foliage color (hues). Finding the old-fashioned green foliage types are almost impossible today, as stunning multi-colored purple, gold, yellow types are entering the marketplace. Ebony colored ‘Black Scallop’ is a personal fav.

Plant ajuga preferably in partial to full shade. In addition to the year-round foliage display or yellow, orange, and red tones, the low grower will produce cobalt blue flowers in spring. Use it to fill in bare spots near structures or entries or simply plant it to complement other shade lovers like pulmonarias and heucheras. At only about 6 inches high, ajuga adds color around other plants without hiding them.

Keep plants within desired boundaries is by enclosing bed plantings with edging like a sidewalk, curb, or permit plants to interlace among steppingstones. Normally, ajuga plantings require little special care. In general, periodic irrigation is the rule. Fertilize ajuga at low rate in early spring. Plant ajuga in sunny spots, although you will need to irrigate more frequently.

Ajuga is highly aggressive groundcover, and it will self-seed after flowering. Deadheading is highly recommended to reduce seedling pop-ups. Snip off some of the runners periodically to curtail its spread. Runners are also easy to dig up and place elsewhere to keep bed with a filled appearance. Cut excess runners and replant them elsewhere or share with garden friends.

New cultivars abound including a vigorous hybrid series from Garden Solutions™®. At this writing, eleven cultivars, including compact forms, have been released.

Ajuga ‘Feathered Friends’ Collection (image from Garden Solutions™)

Princess Flower (Tibouchina)

Posted by Hugh on May 8th, 2025

Princess Flower, aka glory bush (Tibouchina urvilleana) and the lesser-known T. grandifolia are evergreen tropical shrubs and small trees native to Brazil (zones 9-11). In zone 8 plants often dieback to the ground in winter and come back if winter temps remain above freezing. In the U.S. tibouchinas are primarily treated as garden annuals in zones 8 or lower. In tropical areas like Southern Florida, tibouchinas bloom on and off all year long.

T. urvilleana grows 15 feet high and bears large five petalled, purple to lavender colored blooms comprised of five wide open petals that are stunningly beautiful and bloom all summer long where temps are hot and humid on slightly downy, elliptical leaves. T. grandifolia grow only 6 feet tall with wider, round, soft velvety leaves. Flowers are 3- to 5-inches in diameter, and a vibrant deep-purple. Flowers are spiky upright clusters of small blossoms.

Tibouchinas grow best under direct morning sun or all-day dappled light and not in day-long blazing sun. Worldwide, other species are available. Container gardeners often prefer deadheading to encourage the formation of more flower buds and control plant size and form.

*T. grandifolia* has rounded, soft velvety leaves

In temperate areas plant in spring after chance of frosts have ended. Set vegetative cuttings 3-4 feet apart in containers. Princess flower is often trained into tree form and typically reaches 6-8 feet but can grow to 10-20 feet in tropical areas. It can grow 6-8 feet tall outdoors (occasionally to 15 feet); 2-3 feet tall indoors. Princess flower prefers full morning sun and partial afternoon shade.

In areas with moderate mid-South winters (Zones 7 – 8), princess flower is utilized as a garden annual or in containers that can be over-wintered or a greenhouse. Use as a summer patio tree for accent and as a specimen. It’s difficult to overwinter in an unheated garage in borderline zone 8 without a good light and heat source. Showy purple flowers appear in terminal panicles and the tree has a long bloom season. The evergreen foliage is dark green with lighter undersides and are 4-6 inches long. Tip prune lateral branches to desired plant symmetry.

Protect plants from frost and strong winds. In zone 8 or lower, you can plant the princess flower in a container and bring it indoors each winter provided you are able to provide it with enough warmth and sunlight. It prefers moist acidic well-drained soil. In hot summertime areas, it likes some protection from the afternoon sun. It is tolerant of light drought conditions once established and exhibits moderate salt tolerance.

Water containers or garden areas on a regular schedule but don’t overdo it. Feed through the growing season with a slow-release granular fertilizer according to package directions. You might need to supplement feedings with liquid fertilizer and/or bonemeal to encourage more flowering. Troublesome pests include scales, mealybugs and nematodes.

T. *grandifolia* has purple flowers (Atlanta Botanical Gardens)

Princess flower is a member of the botanical plant family: Melastomataceae and is a recipient of the Award of Garden Merit by the Royal Horticultural Society.

Hardy Begonias

Posted by Hugh on May 8th, 2025

Hardy begonia (Begonia grandis) is an herbaceous perennial flowering plant native to Southern China, Japan, and Malaysia. It is a member of the Begonia (Begoniaceae) family (USDA hardiness zones 6-9). From summer into early fall, hardy begonia displays loose arching clusters of bright pink fragrant blooms. It is monoecious, e.g. both male and female flowers are on the same plant. Tuberous-rooted begonias grow a 2-feet tall; they form a bushy mound of foliage on branching stems.

Leaves are bright green and heart shaped. Dangling clusters of delicately fragrant pink (or white) flowers. Hardy begonias can be planted in beds with spring bulbs. Hardy begonias are late comers, e.g. shoots don’t emerge until after spring bulbs have faded. Leaf undersides are brightly red and are especially beautiful, particularly planted in containers and backlit by the late afternoon sun.

Hardy begonias are at their best in shady borders, woodland gardens, or along walkways. They grow best in moist, humus-rich, well-drained soils in part shade to full shade. Do not allow the soil to dry out. Apply a heavy winter mulch where plants are marginally winter hardy in zone 5b. Deadhead flowers to extend their blooming interval.

Begonia leaves turn yellow gradually in the autumn. At the same time, bulbils form in the leaf axils. These tiny asexual formations about the size of a small pea drop to the ground in fall and sprout the following spring. Plants may also self-seed. After a couple of years hardy begonias gradually become a small colony in the garden.

Hardy begonia mixes well with assorted small hostas, astilbes, and ferns in shade or woodland gardens, in shaded border, and in containers. To extend the blooming period, deadhead expired flowers. Disease and insect problems are minimal.

Cultivars

‘Alba’ producespure white flowers with yellow centers on bright pink stems; petals age to a pale pink.

‘Simsii’– hardy begonia is white-flowering cultivar hardy to zone 5b.

‘Torsa’ – develops huge leaves. In year one, leaves reach 10-12 inches long and attain their full 20-24 inches in year 2, plus showy red ribs down the backside.