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

Selecting and Pruning Crape Myrtles

Posted by Hugh on February 14th, 2023

Crape myrtles (Lagerstroemia x indica) are small flowering trees and shrubs. Indigenous to Asia, they have naturalized in our U.S. Deep South. Winter hardiness is a key concern (USDA Hardiness Zones 6-9).

Back in the 1970’s thru the 1990’s, plant breeders at the U.S. National Arboretum released 35 winter hardy varieties, named after North American Indian tribes. They varied in sizes ranging from 5-foot shrubby rose-pink flowered ‘Pocomoke’ to 30-foot white flowered tree ‘Natchez’. The U.S. nursery industry followed suit with 100 more varieties that fit in most landscape designs.

One significant concern with growing crape myrtles is bad pruning, frequently referred to as “Crape Murder”. Don’t let this tragedy happen in your landscape. Before purchase, spend 5 minutes to measure out the space where you will be planting a new crape myrtle. Next, go buy a hardy variety at a garden center in the plant zone. Don’t buy from big box stores unless you are certain the variety is winter hardy!

According to the plant experts at Mississippi State University, here’s the correct way to prune a crape myrtle:

You need sharp pruning tools based on the diameter of the branches and limbs. Use bypass pruners to easily cut back branches up to 3/4 inch in diameter. For branches up to 1 3/4 inches in diameter, use a robust set of loppers. Use a pruning saw on larger branches.

Nicely pruned crape myrtles should be multi-trunked and well-structured. Maintain an odd number of trunks, such as three or five, looks great and preserves enough space for the tree to produce strong growth.

Remove any unwanted trunks. Cut them as close to the ground as you can. Next, choose the height where you want the branching to start and remove lower branches back to the main trunk.

Remove any branches that are growing into the center of the tree canopy and any crossing or rubbing limbs against each other. This creates space and opens the canopy, reducing the chance of diseases. Cut off seed heads to encourage more growth in the spring.

Finish with the removal of small, thin branches. Use your index finger as a size guide to determine which ones to remove. It is common for crape myrtles of any age or size to have suckers sprout up around the base. Use your hand pruners and cut these off without leaving a stub.

Pruning Times for Flowering Shrubs

Posted by Hugh on February 7th, 2023

The late winter / early spring period are ideal times for pruning many (not all) flowering shrubs. At this time, shrubs are leafless, and you are better able to see the overall shape of the shrub and easily identify dead, damaged, diseased wood, and structural defects. Pruning also stimulates new growth.

Spring flowering shrubs (those that bloom before mid-June) should be pruned after flowering. Their flower buds on “old wood” or the previous growing season. Early spring flowering shrubs include quince, evergreen azalea, forsythia, Japanese kerria, lilac, and weigela. The list includes with May blooming rhododendrons and fall and spring flowering camellias.

Summer blooming shrubs such as summerweet (Clethra alnifolia), panicle hydrangea (Hydrangea paniculata), and blue mist shrub (Caryopteris x clandonensis) are pruned in late winter/early spring. Their flower buds form on new wood produced during the current season. Native deciduous azaleas like plumleaf (R. prunifolium)and sweet (R. arborescens) azaleas are best pruned within one month after flowering.

*Hydrangea paniculata* ‘Bobo’ blooming in August

Popular hedging favorites such as boxwoods (Buxus spp.), hollies (Ilex spp.), privets (Ligustrum spp.), barberries (Berberis spp.), and others are pruned 1-3 times during the growing season. In most areas all hedging should cease by mid-September. Do not shear hedges to the same height as this will destroy formation of new growth buds.

For old or overgrown shrubs that bloom poorly and are still healthy growth-wise, try rejuvenation pruning in early spring. Cut all stems back to the ground. Shrubs usually grow back quickly after fertilizing and flowering resumes in 1-2 years. Plants that respond well to rejuvenation include crape myrtle, forsythia, lilac, and spirea.

To finish fall is not a desirable pruning time as new pruning cuts at that time of year is subject to winter injury.

Pruning timetable for many flowering shrubs:

Spring Flowering Shrubs (Prune After Flowering)

Serviceberry shadbush (Amelanchier spp.)

Azaleas (Rhododendron spp.)

Barberry (Berberis spp.)

Beautyberry (Callicarpa spp.)

Sweetshrub (Calycanthus floridus)

Camellia (Camellia x)

Flowering quince (Chaenomeles spp.)

Dogwood (Cornus spp.)

Cotoneaster (Cotoneaster spp.)

Daphne (Daphne spp.)

Deutzia (Deutzia spp.)

Forsythia (Forsythia spp.)

Fothergilla (Fothergilla spp.)

Witchhazel (Hamamelis spp.)

Smooth Hydrangea (Hydrangea arborescens)

Oakleaf Hydrangea (Hydrangea quercifolia)

Mountain laurel (Kalmia latifolia)

Kerria (Kerria japonica)

Golden chain (Laburnum anagyroides)

Privet (Ligustrum spp.)

Spicebush (Lindera benzoin)

Honeysuckle (Lonicera spp.)

Chinese Fringe Flower (Loropetalum chinensis)

Mockorange (Philadelphus coronarius)

Ninebark (Physocarpus orbiculatus)

Japanese Pieris (Pieris japonicus)

Firethorn (Pyracantha spp.)

Currant or gooseberry (Ribes sanguinea)

Roses (Rosa spp.)

Rhododendrons (Rhododendron spp.)

Spiraea (Spirea spp.)

Lilac (Syringa spp.)

Viburnums (Viburnum spp.)

Weigela (Weigela florida)

Summer Flowering Shrubs (Prune in Spring)

Flowering abelia (Abelia x grandifolia)

Butterfly bush (Buddleia x spp.)

Beautyberry (Callicarpa spp.)

Blue Mist (Caryopteris × clandonensis)

New Jersey Tea (Ceanothus americanus)

Summersweet (Clethra alnifolia)

Rose of Sharon (Hibiscus syriacus)

Bigleaf hydrangea (Hydrangea macrophylla)

Panicle hydrangea (Hydrangea paniculata)

St John’s Wort (Hypericum spp.)

Crape myrtle (Lagerstroemia spp.)

Cinquefoil (Potentilla fruticosa)

Sweet azalea (Rhododendron arborescens)

Plumleaf azalea (Rhododendron prunifolium)

Sumac (Rhus spp.)

Roses (Rosa spp.)

Anthony Waterer spirea (Spiraea x bumalda)

Chaste tree (Vitex agnus-castus)

Winter Blooming Vernal Witchhazel

Posted by Hugh on January 30th, 2023

Vernal witchhazel is a U.S. native to the Ozark Plateau extending from southern Missouri through northwestern Arkansas to eastern Oklahoma. It is among the easiest of shrubs to grow @ 10-12 feet tall and two-thirds as wide. Roots spreads by underground stoloniferous.

The leaves are oval, 2³⁄₄–5 inches long and 2 1/2 –5 inches wide and are slightly oblique at the base. Leaf edges are wavy-toothed and shallowly lobed. Leaves are dark green above, and glaucous beneath, and often persist into the early winter.

Flowers are deep to bright red, rarely yellow, with four ribbon-shaped petals 0.28–0.39 inches long with four short stamens arranged in clusters. Flowers of vernal witchhazels emerge in late winter (December to March). On warm wintry days native and some honeybees work the fragrant blooms

Tiny individual fruits (³⁄₈–⁵⁄₈ inch long) are dehiscent hard woody capsules which split explosively at the apex at maturity one year after pollination and propel two shiny black seeds 30 or more feet from branches. Seeds take up to two years to germinate.

Most witchhazels may also be started by vegetative cuttings collected in early winter and rooted in a cool greenhouse under bottom heating. Pruning, if needed, can be performed in any season. Rarely in a wild population will you come upon a variant (see cultivars below).

‘Amethyst’ – is a rounded bush that grows 8 to 10 ft. tall and wide with
gray-green foliage that turns a brilliant red and orange in autumn. Deep
red purple flower best backed by some lighter color. lightly fragrant, reddish purple blossoms in mid-winter.

‘Quasimodo’ – a semi-dwarf selection (4-6 feet tall) introduced to the European nursery industry in 1980. Light orange flowers are highly fragrant, along with a compact-spreading habit. Spring foliage is richly greenish-blue and remains quite attractive throughout the season.

‘Autumn Embers’ – an 8-10 feet shrub with showy, fragrant, copper-red flowers.

Precise Care For Calatheas

Posted by Hugh on January 24th, 2023

Calatheas, also called Peacock plants, are among the most beautiful of foliage house plants, but their care can be challenging. Plants prefer low to medium bright spot in your home and look their best away from direct sunlight. The key to success is high room humidity and are best paired up with similar tropical favorites like philodendrons and Phalaenopsis orchids.

Select plastic, terra cotta, or ceramic containers. The pot should be two inches wider than the one it was purchased in. Grow calatheas in a humus-rich peat /bark /perlite growing media that retains moisture. The soil needs to be moist much of the time to permit roots to breathe. Calathea roots love moist soil but resent overwatering or letting pots set in saucers of water over long periods; this often leads to root rots and eventual loss of the plant.

Houseplants need a regular dose of fertilizer to look their best. The best time to fertilize is when the plant is actively growing; for most plants that means fertilizing in the spring and summer (mid-March to mid-October).

*Calathea lancifolia* (Rattlesnake Plant)

Feed calatheas a weak solution of fertilizer and be careful not splash fertilizer on their sensitive foliage. Calathea leaves are highly sensitive to chemical burn. Similarly, over-fertilizing your Calathea could cause the roots to burn, and this will slowly kill the plant.

Calatheas are susceptible to few pests, principally spider mites and mealybugs. Inspect plant(s) regularly and treat pests is to clean the leaves with a mixture of water and dish soap in a spray bottle. As houseplants calatheas are not harmful to pets and young children. Pruning-wise, remove old worn leaves that have lost most of their decorative color(s).

Plants hobbiests are currently witnessing a calathea renaissance. Some leading varietes are: C. lancifolia (Rattlesnake plant), C. orbifolia, C. ‘Roseopicta’, C. veitchiana ‘Medallion’, and C. zebrina (Zebra plant).

Propagate your plant by separating the plant’s root mass with a sharp knife.

Calatheas are not harmful to pets and young children.

Growing Jewel Orchids

Posted by Hugh on January 12th, 2023

Jewel Orchids (Ludisia discolor) are native to the tropical forests of Southeast Asia. Compared to the tree-climbing epiphytic Phalaenopsis and Cattleya orchids, Jewel Orchids are terrestrial plants that grow on tropical forest floors. Jewel orchids are grown primarily for their spectacular dark and colorful veined ovate foliage and secondarily for their flowering.

Jewel orchid at Biltmore Estates in Asheville, NC

Jewel orchids grow in low light and high humid environs; their roots grow in soil-less media containing sphagnum peat moss or coarse bark. Consider them as low light house plants in 80%-90% shade. Leaves feel velvety and are quite decorative with red-white or golden veins; leaf colors are burgundy to maroon to richly green.

Jewel orchids bloom once yearly, primarily in winter. Plants produce clusters that rise up on long floral spikelets above the dark exotic foliage. Jewel orchids grow well in well-drained, slightly damp soils. You need to lightly fertilize every 2-3 weeks during the spring-summer growing season and half that in late fall and winter months.

Flowering is something to look forward to. Small white flowers appear on long spikes that shoot up. Flowers may lack fragrance, but the bloom stalks are lovely over 4-5 weeks.

Common growing problems are twofold: 1. root rot, likely caused by overwatering or poor media drainage, and 2. brown, curling leaves caused by low humidity or excess light. Foliage spotting is an early symptom; follow up immediately to alter the plant’s environment.

Jewel orchids are not commonly available local garden centers but are sold at on-line plant sources. Two genera – Ludisia discolor and Macodes petola – are popularly listed online. L. discolor ‘Alba’ – leaves are bright green with white veins and white flowers.

There are other genera of jewel orchids to collect: Ludochilus, Anoectochilus, Dossinochilus, and hybrids thereof. Lightning Bolt Jewel Orchid (Macodes petola (velvety leaves / silver veins) and Lava leaf orchid (M. sanderiana x limii).

Jewel orchids are fast growing and make terrific terrarium plants. Repot the plant annually to refresh the soil.

2023 Triple Crown Winner: ‘American Gold Rush’ Black-eyed Susan

Posted by Hugh on January 6th, 2023

For 2023, three leading organizations, All-America Selections, National Garden Bureau and Perennial Plant Association, have awarded a cultivar of black-eyed Susan their highest plant award in the U.S. For the U.S plant Industry this is the first time ever.

Currently, garden interest in rudbeckias is at an all-time high. All-America Selections judges evaluated ‘American Gold Rush’ for three years and noted how easy it was to grow and is an exceptional perennial as well. The variety was very attractive in the perennial garden with nice full bloom coverage late in the season.

‘American Gold Rush’ is a top garden performer. It is full of flowers by mid-summer and expect a long season of dazzling color right up to autumnal frosts. Its narrow 2-inch wide, hairy green foliage is resistant to Septoria leaf spot – a nasty fungal disease that causes unsightly black spotting and premature seasonal decline on some rudbeckia varieties. It’s a reliable hardy perennial and a stunning focal point in perennial borders and meadows as well as being brilliant when massed in public or corporate landscapes.

In the world of perennials rudbeckias are very easy for TN /VA gardeners to grow. Rudbeckias are native to much of North America. Rudbeckias are pollinator friendly and there are many new varieties to try.

American Gold Rush at Dawes Arboretum in Ohio (Late September)

‘American Gold Rush’ is a compact hybrid cultivar, only 24 inches high compared to the slightly taller ‘Goldsturm’. Bright, yellow-gold flowers cover the plant from July to September and attract lots of pollinators. Black-eyed Susans grow in average, moist, well-drained soils in full sun, although plants will tolerate partial sun (4 hours/day). New plantings prefer supplemental irrigation during dry spells. Established plants are more drought tolerant. Good air circulation is best, so don’t crowd plants together. Deadheading is not necessary as this award-winning cultivar blooms almost continuously into the first fall frost. Plants slowly spread via rhizomes. (Zones 3-9)

Pantone’s 2023 Color of the Year

Posted by Hugh on January 1st, 2023

In case you didn’t already know, Pantone Color Institute has become a worldwide color authority with identifying trendy colors consumers will crave in the New Year. Their Color of the Year selections are often featured in fashion, interior design, outdoor living products and even in landscape plants.

Pantone’s 2023 Color of the Year is Viva Magenta 18-750.

For 2023, Viva Magenta may be more widely used on garden furniture or painting your front door. Perhaps, you may desire to plant magenta colored flowering annuals and perennials on your patio or deck.

Here is a short list of perennials to plant in your landscape that complement the Pantone Color Institute’s 2023 Color of the Year.

Achillea ‘Tutti Frutti Pomegranate’

Agastache ‘Kudos Red’

Coreopsis ‘Lil Bang Red Elf’

Coreopsis ‘Hot Paprika’

Coreopsis ‘Uptick Red’

Crocosmia ‘Lucifer’

Dianthus ‘Fruit Punch’ Cherry Vanilla’, ‘Maraschino’, ‘Pretty Poppers Electric Red’, ‘Paint The Town Magenta’

Echinacea ‘Meteor Red’, ‘Raspberry Beret’

Hemerocallis ‘Double Pardon Me’, ‘Blood, Sweat and Tears’

Heuchera ‘Dolce Cherry Truffles’

Hibiscus ‘Holy Grail’

Hibiscus ‘Mars Madness’, ‘Evening Rose’

Kniphofia ‘Red Hot Popsicle’

Lobelia cardinalis (Cardinal flower)

Monarda ‘Leading Lady Razzberry’

Penstemon ‘Quartz Red’, ‘Cha Cha Cherry”

Phlox paniculata ‘Red Riding Hood’, ‘Starfire’

Sedum ‘Sunsparkler Cherry Tart’, ‘Midnight Velvet’

Spigelia ‘Little Redhead’

Thank You — Nicole Hoonhorst at Walters Gardens & Paul Pilon at BallHort for some plant picks

Raise The Humidity Around House Plants

Posted by Hugh on December 28th, 2022

Tropical plants thrive in a 70-75° F room temperatures during the fall / winter months. Frequently, the central heating system is running at maximum warmth and results in low room humidity. The lush foliage of many tropical plants suffers leaf edge burn and tip dieback caused by low humidity. Here are nine (9) methods listing ways to raise room humidity. You may need to employ two or more methods.

1. Mist Plants Daily

Misting plants is one of the easiest and most interactive ways to raise humidity around your plants. Misting your plants not only raises humidity you’re inspecting them for disease and pest problems and caring for some individually.

2. Place pans and bowls with water nearby your plants

Setting containers of water around plants slowly evaporates water, thereby raising humidity levels.

3. Best Room To Grow Plants

Bathroom, Kitchen, and Laundry are the best rooms to grow house plants. Showering, cooking, washing dishes and drying clothes raise humidity levels on your home.

4. Pebble Trays Boost Humidity

Cafeteria serving trays or old plates and saucers no longer in use, filled with pebbles and small rocks, support pots and plants. The pots do not sit in puddles of water. Excess water between the stones slowly evaporates and raises room humidity. Do not fill too much water in the tray which may lead to root rot.

5. Room humidifier

A room humidifier maintains your apartment or home at a desired humidity level over the fall and winter months. A small portable unit raises a humidity around your plants. You might even be able to set it anywhere in the room to benefit several plant groupings within a large room.

6. Give Tropical Plants Their Weekly Shower

Keeping the bathroom door ajar while showering spreads humidity to adjacent rooms. Also, move plants into a tub weekly and give them a short 3-5 minute shower. It waters the roots, raises humidity, and washes off the dusty leaves

7. Have an aquarium nearby your plants

A nearby fish tank or aquarium sited close to your plants. The water surface gradually evaporates and raises the room humidity levels. Combining a plant collection with an aquarium is a decorative look great looking water plants.

8. Set plants close together

House plants breathe and add humidity to your home. Water evaporates from leaves and soil thereby raising room humidity. Place tropical leafy house plants in close proximity to one another. With certain tropicals, such as orchids and bromeliads, supply higher humidity by employing a multiple of methods.

9. Build a terrarium

A closed terrarium offers an ideal environment to plants demanding high humidity levels. Examples include nerve plant (Fittonia), African violet (Saintpaulia), anthuriums, orchids, and Venus flytraps.

NewGen Boxwoods

Posted by Hugh on December 15th, 2022

Boxwoods (Buxus spp.) are the quintessential shrubs, primarily utilized as a foundation plant, a formal medium hedge, or for low privacy screening. Over the past half century, many new boxwood varieties have been introduced into nursery commerce. Boxwoods work in most landscape situations and are deer resistant. Only a few years ago, boxwood production at U.S. nurseries was greater than for azaleas, hollies, hydrangeas, and arborvitaes.

NewGen Freedom® Boxwoods at Saunders Bros Nursery

Brief History– The impact of boxwood blight (Calonectria pseudnaviculata) on nursery sales has been crippling. Professional landscapers and homeowners could no longer guarantee that the boxwoods they purchased were disease-free. Boxwood relatives, such as Japanese spurge (Pachysandra terminalis), Allegheny spurge (P. procumbens), and Sweetbox (Sarcococca spp.), are also susceptible to boxwood blight.

Additionally, other boxwood diseases and pest problems – namely Volutella canker (Volutella buxii), boxwood leafminer, and midge — have become major concerns here in the U.S. and internationally.

Solution– Plant scientists and nursery growers now have a better understanding about the disease organism that causes Boxwood Blight and how to manage it. The best news is that two highly resistant varieties are now coming to garden centers.

NewGen Independence® Boxwoods at Saunders Bros Nursery

NewGen™ Boxwoods are a new family of boxwoods that offer greater resistance to diseases and pests, as well as incredible landscape performance. After many years of testing in the landscape, production, lab, and trial gardens across the U.S., Saunders Bros Nursery has debuted two boxwood varieties that are Boxwood Blight resistant. This wholesale nursery is located in Roanoke Valley area in central Virginia,

NewGen Independence® (PP28888) is a mid-sized boxwood highly resistance to both Boxwood Blight and boxwood leafminer. It has glossy deep green foliage and a medium rounded growth habit (@ 2 to 4 inches per year, nearly as tall as wide). Size: 15 years (3 feet tall and 3 feet wide) 25 years (4.5 feet tall and 4.5 feet wide). Substitutes for: English Boxwood (Buxus sempervirens ‘Suffruticosa’), ‘Green Beauty’, ‘Green Velvet’, and ‘Green Mound’. (Zones 5b-8).

NewGen Freedom® is highly resistance to Boxwood Blight and to boxwood leafminer. It grows vigorously @ 3 to 6 inches per year along with lovely glossy medium green foliage. Size: 15 years (3.5 feet tall and wide); 25 years (5 feet tall and wide). grows slightly taller than wide. Substitutes for: ‘Wintergreen’, ‘Winter Gem’, ‘Jim Stauffer’, ‘Green Mountain’. (Zones 5-8).

Creating A Tropical Look

Posted by Hugh on December 8th, 2022

Here are some ideas for designing a tropical landscape in your yard. Start with large leafy trees that are hardy in zones 6-7 include catalpa (Catalpa spp.), hickories (Carya spp.), some oaks (Quercus spp.), large leaf maple (Acer macrophylla), American sycamore (Platanus americana), American linden (Tilia americana), and Empress tree (Paulownia tomentosa). In zones 7-9 add Chinese parasol tree (Firmiana simplex), and in zones 8 -10 add Mexican sycamore (P. mexicana).

Enormous leaves of Paulownia (Empress tree) cutback

Big leaf magnolias are also tropical looking. These five underplanted magnolias are highly dependable trees in large landscapes — Bigleaf (Magnolia macrophylla), Ashe magnolia (M. ashei), (M. tripetala), and cucumber magnolia (M. accuminata). Four of five species are U.S. natives.

Large 20+ inch long leaves of *Magnolia macrophylla*

Have a small landscape? Cutback these young trees in late fall and new spring growth will sprout with much larger leaves and will not flower.

Hardy bananas (Musa basjoo) and angel trumpets (Brugmansia) thrive zone 7 hardy and in protected areas of zone 6b. Protect the roots and crowns with a winter blanket of mulch or pine needles. Both species dieback to the ground surface in fall.

GROW TROPICALS AS ANNUALS – Leafy tropical favorites such as papyrus (Cyperus papyrus), caricature plant (Graptophyllum pictum), elephant ears (Colocasia ‘Thailand Giant’), and variegated tapioca plant (Manihot esculenta ‘Variegata’) grow rapidly. Buy young vegetative plants to pre-started in a warm greenhouse @ minimum 60°F temps prior to safely planting outdoors when the frost threat has passed. Some of these tropical plants finish the growing season @ 4-8 feet high and wide and die off with the arrival of a wintry chill (USDA hardiness zones 9-11).