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

Substitutes For Callery Pear

Posted by Hugh on November 15th, 2023

Bradford Pear (*Pyrus calleryana* ‘Bradford’)

The end to planting Callery pears (Pyrus calleryana), aka Bradford Pear, is almost within sight as more states are banning sales of the tree at garden centers and box store garden departments. Recently, Ohio, South Carolina and Pennsylvania have banned further plantings.

This March blooming flowering tree has been determined to be invasive. It produces fruits in the fall which competes with native flora in many states. The average gardener will likely know the callery pear by its varietal name “Bradford pear”.

Callery pears are reliable spring bloomers, the trees covered with white blossoms for 2-3 weeks in late winter and early days of spring. In most years trees strut an exceptional crimson red leaf color in late autumn. Trees have few disease or insect problems, are adaptable to a wide range of soil conditions, and cope on urban sites.

Wild callery pears aggressively compete and frequently displace the native plant species growing on the site. They have invaded natural woodlands and parks. It has become a problematic tree as well. Callery pears are not a long-lived tree, rarely lasting more than 25 years. The tree has a weak structure at the “V” of the branches.

Tree branching is notorious brittle resulting in limb breakage during ice and windstorms, often resulting in the tree’s removal. Limbs snap off in areas from old age. Further, blooming trees emit an unpleasant fragrance. Seedling trees produce sharp pointed thorns which snag clothing during pruning or puncture tires if you attempt to drive over fallen branches.

Bradford pear flowers are self-incompatible, that is, they do not fertilize other ‘Bradford’ pears flowers. However, they successfully pollinate other callery pear varieties, such as ‘Redspire’, ‘Aristocrat’, ‘Chanticleer’, ‘Whitehouse’, and ‘Cleveland Select’ among others. These varieties produce tiny, hard pear fruits, each ½-inch in diameter, green to brown in color, and contain viable seeds. Birds or other animals eat these fruits and disperse the seeds across the countryside.

Consider these spring flowering trees when replacing Callery pears: Redbuds (Cercus spp.), Crabapples (Malus spp.), Flowering Dogwood (Cornus florida), Serviceberry (Amelanchier spp.), Flowering Cherries (Prunus spp.), and Carolina Silverbells (Halesia diptera). In mid-South locations, early flowering deciduous Magnolias are also better alternatives to callery pears.

If you spot wild callery pears seedling trees growing on your property, cut them down and paint the stump with any herbicide containing the ingredient Glyphosate® to prevent the tree from resprouting.

Planting Under Trees

Posted by Hugh on November 7th, 2023

*Selaginella braunii* at Biltmore Estate in Asheville NC in winter

Here is an idea that I picked up at Chanticleer Gardens in Wayne, Pennsylvania and pollinators will also love you for it. When planting a deciduous tree, make good use of the ground area beneath the tree by planting shade tolerant ground covers. Evergreen trees don’t work here. You can also create a beautiful planting bed of assorted perennials at the edge of a woodlands.

Many gardeners will automatically plant hostas, coral bells (Heuchera spp.,) or assorted ferns. All are great choices. Here is a lengthy list of long-lived shade perennials: Lenten roses (Helleborus x), foamflower (Tiarella), Hakone grass (Hakonechloa macra), woodland phlox (Phlox divaricata), Bigroot geranium (Geranium macrorrhizum), lilyturf (Liriope spicata), deadnettle (Lamium), lungwort (Pulmonaria saccharata), wild ginger (Asarum canadense), moss fern (Selaginella braunii), astilbes (Astilbe spp.), coralbells (Heuchera villosa), (Brunnera macrophylla), Spotted deadnettle (Lamium maculatum), hardy begonias (Begonia grandis), pachysandra, Ajuga (Ajuga reptans), barrenwort (Epimedium spp.), Pennsylvanica sedge (Carex pensylvanica), and two favorite shade ferns – Christmas fern (Polystichum acrostichoides) and male fern (Dryopteris filix-mas). Don’t leave out planting late winter blooming bulbous flowers such as snowdrops (Galanthus nivalis) and winter aconite (Eranthis hyemalis) or fall blooming rain lilies (Zephyanthes).

Dry shade is the area (or shade) found under a canopy of a huge, deciduous or leaf-shedding trees. It is called ‘dry’ since the area often lacks moisture partly due to the maturity of the tree. Low growing hydrangeas also work under trees with supplemental irrigation. Recommend Mountain hydrangeas Tuff Stuff® series or Let’s Dance® bigleaf hydrangea series (Hydrangea macrophylla), Summersweet (Clethra alnifolia ‘Hummingbird’ and dwarf Japanese andromeda (Pieris japonica). They won’t thrive under dry soil conditions.

Use an augur, hand trowel, or hori (digging knife) to set most plants. Opt to plant 3 or more of each variety for visual impact of the colorful foliage or flowers during the season. Add plants with bold colors or variable foliage textures. This can add beauty to your dry shade and would surely catch some attention.

Adding ground cover plants under established trees is rarely successful, particularly if the trees are shallow-rooted. As stated earlier, you might try to drill in small flowering bulbs like crocus and snowdrops deep rooted established dogwood, redbud or crape myrtle. Do not add 2 or more inches of topsoil under established trees in order to sow ground plants and bulbs. This would deprive tree roots of needed oxygen.

Rattlesnake Master

Posted by Hugh on October 31st, 2023

Rattlesnake master (Eryngium yuccifolium) is mostly at home in a hot sunny prairie environment in the Southeast and Midwest (USDA hardiness 3-8). Its spiny nature gives it a desert spiny yucca-like appearance. Some Indian groups were known to brew the plant’s roots as an antidote to rattlesnake venom. Some native peoples also used the dried flower stalks as ceremonial rattles. No, the plant does not attract rattlesnakes.

Rattlesnake master is a perennial herb in the carrot (Apiaceae) family. The iris-like plant grows 2-5 feet tall and 2 feet wide. It is characterized by alternate, long, narrow blue-green leaves with a sharp tip. Widely scattered stiff spines are formed along the leaf margins. Leaves measure up to 3 feet.

Rattlesnake master is an easy plant to grow. It grows in almost any soil, including clay soils, dry soil, even shallow rocky soil. Good soil drainage is highly important to this prairie inhabitant. Its water use is medium; once established, it can also withstand long drought periods lasting 3-4 weeks. It is highly resistant to diseases and insects. Deer and rabbits tend to stay away.

From July to September, thistle-like greenish-white flower balls, ½ to ¾ inch wide, are arrayed in ball-like clusters atop a tall smooth stalk. Each flower head is comprised of numerous small flowers with 5 white petals that emit a honey-like fragrance. Surrounding each flower is a whorl of prickly leafy bracts. It spends its first year developing a deep root system. Flowering often begins blooming in the second season. The garden should be in full sun and in lean (unfertilized) well-drained soil.

Leaves are mostly basal, long and sword-like with parallel veins and tapering to a sharp point, up to 2½ feet long and only 1-inch wide with a few smaller leaves ascending the stem. Leaf surfaces are waxy, the edges either smooth or commonly with widely spaced, fine spiny teeth. Stem leaves are stiff and typically wraps itself around the stem. Stems are hairless, blue-green, waxy, and ridged.

Seed propagation is your best option. Saved seed should be cold stratified at 40°F for two months and then sowed in spring. Established plants can be divided in late spring or fall. Plants do not transplant well. Likewise, deadhead spent flowers to avoid seed dispersal and self-sowing.

Extra: At Southeast Research and Extension Center in Lancaster County, Pennsylvania, rattlesnake master ranked in the top third of plants with the greatest total number of pollinator visits for both pollen and nectar. It is highly valuable bees, wasps, flies, butterflies, skippers, moths, beetles and other plant insects.

Other Eryngium spp. of garden interest: Oliver Sea Holly (E. x oliverianum) and Flat Sea Holly (E. planum ‘Blue Cap’).

January Blooming Vernal Witchhazel

Posted by Hugh on October 21st, 2023

This winter – follow your nose to Vernal witchhazel (Hamamelis vernalis), aka Ozark witchhazel. (USDA zones 4-8). This U.S. native witchhazel grows as a deciduous shrub to small tree. It may produce the smallest flowers of all witchhazel species, but they’re highly fragrant when little else is blooming. It naturally inhabits a wide area encompassing from southern Missouri to northwestern Arkansas and eastern Oklahoma.

New leaves emerge bronze to reddish purple and fall foliage finishes golden brown and often persists into early winter. Leaves are almost circular, measuring 2.5 to 5 inches long and wide, with a slightly oblique base and leaf tips are acute or rounded. Leaves are dark green above and glaucous beneath with a wavy-toothed or shallowly lobed margin and short, stout petiole.

Its dark yellow (gold) blooms appear from January to March and age to dusky red. Flowers are comprised of four narrow ribbon-like petals, barely ¼ to 1/3 inches long with four short stamens. On warm 50°F winter days, watch for bees buzzing around the fragrant blooms.

Tiny individual fruits (³⁄₈–⁵⁄₈ inch long) are hard woody capsules that split open to explosively at the apex at maturity one year after pollination, each one ejecting two shiny black seeds 30 or more feet from the parent plant. Three vernal witchhazel cultivars are:

‘Amethyst’ – has a rounded form, 8 to 10 feet tall and wide, and gray-green spring/summer foliage that turns a brilliant red and orange in autumn. Deep red purple flowers are lightly fragrant and finish reddish purple in mid-winter.

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

‘Sandra’- grows 6-10 feet tall and 8-10 feet wide with fragrant golden strap-like flowers from mid-winter to the first days of spring.

Vernal witchhazel spreads underground slowly via stoloniferous root shoots. Annual maintenance other than pruning is unnecessary. Maintain the natural shape of the shrub and rein in its root suckering to fit its intended landscape space. Annual fertilizing is generally unnecessary. If the summer foliage became chlorotic (yellow), apply 1-2 handfuls of elemental sulfur in the fall or feed with an acidic fertilizer like Miracle-Gro or Schultz in spring and early summer. Apply 3-4 inches of bark mulch or pine needles in spring.

Where to purchase: online native plant nurseries.

Burls on Tree Trunks

Posted by Hugh on October 12th, 2023

An unusual swelling on trunks of trees and occasionally on large branches are “burls”. They’re round, swollen-looking growths on tree trunks and large scaffold branches. Should or shouldn’t you be concerned? Burls are not uncommon and can be found on cherry, maple, oak, buckeye, ash, willow, locust and walnut in Eastern forests. Root burls may also be found on rhododendron and laurel.

The cause of tree burls is a bit of a mystery. Plant scientists don’t know why they occur. In general, burls develop because of invasions (bacteria, fungi, and insects) or stressors (freeze damage, mechanical, and environmental injury). Certain tree species are genetically predisposed to develop one or more burls while other nearby trees may not likely form any.

Are burls bad for trees?… Usually not. Burls typically don’t do any harm to trees. On rare occasions, a burl may disrupt the tree’s vascular (circulatory) system. As it turns out, though, getting rid of them may pose the significant risk. Cutting burls would leave large wounds on the tree’s trunk and branches, which could lead to an infection or weaken the tree’s structural stability.

Burls may occur on tree roots and go largely undetected. Also, it is best not to remove the bumps on tree branches or tree trunks. However, you may clip away sprouts that emerge out of the burls.

Burls themselves generally don’t cause problems for your tree, but you should try to determine the root of the growth and address it. Consult a certified tree arborist to determine the cause and solution.

Since burls can be a result of insect or fungi damage, inspect for signs that point to an insect or disease infestation. Look for small holes in the trunk and branches, sawdust, or insects crawling around. Also, inspect the trunk or branch wood for evidence of decay including cavities, missing bark, root damage or wounds.

Conifer species in Alaska (Photo courtesy of Mary C. Rice)

Finally, burl wood is expensive and treasured by woodworkers and carpenters alike. Consult a Certified Tree Arborist in your state or city by searching the International Society (ISA) directory.

Uniquely Different Weeping Mulberry

Posted by Hugh on October 3rd, 2023

Common (White) mulberry (Morus alba) is a fast-growing, medium sized, deciduous tree that typically grows to 30-50 feet tall and wide. It usually develops a wide-spreading rounded crown with age. This native to China is utilized either as a landscape shade and/or a fruit tree. (USDA hardiness zones 5-9).

White Mulberry prefers a rich, moist, well-drained soil and full sun. The tree tolerates a wide range of environmental conditions including moderate shade, pollution, salt spray, extreme heat, infertile soils, a wide range of soil pH, and moderate drought. It is notoriously shallow rooted.

Mulberries are easy to identify by their large lobed leaves and their edible fruits – a delicious treat as well as a weedy seed problem. Individual leaves may be unlobed, mitten-shaped, or 3-lobed. Mulberry trees are polygamo-dioecious; they produce only male or female flowers on one plant or both flower types are present on the same tree. In June and July, female trees produce an annual crop of white, red, purple or black fruits that resemble long, thin blackberries. Prune mulberry in late fall or winter to avoid sap bleeding in spring.

Mulberries are a popular food source for many species of birds. Unfortunately, the fruit and resulting bird droppings are messy and will stain pavements, automobiles and areas around the home. Weeping cultivars are mostly fruitless which limits its threat as an invasive species.

No serious insect or disease problems trouble mulberries. The tree is not deer resistant. Borers are troublesome in some years in the South. Whiteflies, scale, mites and mealybugs are occasional pests. Bacterial blights and leaf scorch, powdery mildew, and root rot are usually indicators of poor site selection.

Weeping mulberry trees are exceptional unique, trouble-free, and should be planted more. Three major weeping forms are available.

M. alba ‘Pendula’ has a dwarf weeping form that matures to 8-15 feet, sometimes to 20 feet height. It creates a unique and beautiful presence in any garden! Its matchless contorted trunk and branches are revealed from late autumn thru winter.

M. alba ‘Chaparral’ is a superior weeping, male seedless form that grows 8-12 feet tall and is equal width. This male fruitless selection produces yellowish-green catkins in spring.

M. alba ‘Nuclear Blast’ (‘Itoguwa’) is a 3-4 feet tall and wide shrub oddity! Thread-like foliage appears shredded or deformed.

Gooseneck Loosestrife

Posted by Hugh on September 22nd, 2023

Gooseneck loosestrife (Lysimachia clethroides) can be both a delight and a weedy nuisance – depending on where you garden. (USDA hardiness zones 3 – 8). This native of southeast Asia grows aggressively in some locations in the U.S. where it has escaped into woodlands, wet areas, and on sunny, sheltered mountainous slopes. The perennial has upright rigid branching which bear unique white flowers (racemes) that bloom from June through August.

Gooseneck loosestrife is a fast-spreading plant that prefers partial sun and moist well-drained soil. Keep this aggressive perennial in check as it spreads aggressively via rhizomes and may become weedy from seed dispersal. It grows less aggressive in shady, dry soils although flower numbers are fewer and growth may be leggy.

Gooseneck loosestrife grows 2 -3 feet height and 3 feet spread. It can also be utilized as a groundcover. Leaves are slender with a tapered point. Raceme flowers average 12-18 inches in length and pure white. The fall foliage takes on gold to yellow tints. In northerly latitudes, gooseneck survives frigid winters by blanketing a 2–3-inch layer of mulch around the plant base.

In early spring, cut back all the stems to within 2 inches of the ground. Spring growth emerges from the crown and flowers appear in June until October. Keep it cornered in planting areas bounded by hardscaping. Every 3-4 years divide rhizomes in the spring to both limit its spread yet invigorate this rhizomatous plant. Judicious deadheading of spent flowers triggers reblooming and reduces seed formation. Flowers are particularly attractive to butterflies. It is relatively deer resistant.

Commercially, gooseneck loosestrife is produced by the cutflower florist industry. Floral stems may last over a week. Gooseneck earns its name for its flower spikes that mimic the curve of a goose’s neck.

Varieties:

‘Lady Jane’ (seed and vegetative produced) produces pure white blooms in late summer.

‘Geisha’ grows 2 feet tall with creamy yellow margin foliage; less aggressive (tamer) than species; 1-foot-long nodding white flower racemes in late summer.

Three Salvias To Try

Posted by Hugh on September 16th, 2023

Back in early spring you may have planted several kinds of salvias (sages). The arrival of the cool autumn weather turns up the flower power of sages. They’re members of the mint family and the leaves emit a mild anise scent when crushed.

Looking ahead to summer of 2024, here are three salvias that you might try in your garden. All are native to central South America (zones 8-10). There are no guarantees that plants will survive TN, VA or NC winters as they’re rated as tender perennials there.

Blue anise sage (Salvia guaranitica) is primarily grown as a garden annual in TN. Through most of summer into fall, its electric blue, two-lipped, tubular, 2 inches long flowers contrast strikingly with the blackish stems. ‘Black and Blue’ is hardier than other cultivars and often survives milder winters if well-mulched. Plants develop a shrubby, somewhat open habit with upright branching, to 3-5 feet tall as a perennial and 2 ½ to 3 feet tall as an annual in garden beds and in large containers. ‘Black and Bloom’ is a newer variety rated more heat, humidity, and drought tolerant. It will survive milder winters. Dark green roundish leaves measure 2-5 inches in length.

Friendship Sage (Salvia x) is a showy violet-purple blooming sage. The variety ‘Armsted’ will perennialize in zone 7b and further south. It has a very long bloom season and flowers are pollinator favorites. Armsted is grow vigorously, forming a bushy 4–5-foot plant covered with spikes of purple flowers which stand above the foliage.

Fuzzy Bolivian Sage (Salvia oxyphora), aka Bolivian Spearhead Sage, is fairly new in the local garden trade, but their bright, hot pink, fuzzy blossoms will surely make them a favorite. (Zones 8-10). Fuzzy Bolivian Sage grows vigorously and can reach 4 feet high by the end of summer. The plant’s deep green tropical-like foliage is glossy green with clear, almost invisible hairs. The fuzzy hot pink spikes of flowers appear in late June and plants continue blooming through the October frost, with terminal clusters of hairy rosy-pink tubes.

General Care: Plant any of these salvias in humus-rich, medium moisture, well-drained soil in full sun to partial shade. Salvias become moderately drought tolerant 6-8 weeks after spring planting. Use in the middle of the flower gardens or in containers. This is a reliable nectar source for butterflies and hummingbirds and is seldom damaged by deer.

Perennials With Great Fall Color

Posted by Hugh on September 10th, 2023

*Geranium sanguineum i*n December landscape

In general, perennials are not rated very high for their fall leaf color. This is very wrong as some produce stunning autumnal foliage colors. In addition, some ornamental grasses produce colorful floral heads (inflorescences).The first six are perennial dicots and the next six are grasses with awesome inflorescenses.

Bloody cranesbill (Geranium sanguineum) – short 9-12 inches high clump forming groundcover that bears purple flowers in May-June. Its deeply cut foliage green leaves turn shades of red after first frost. (Zones 3-8).

Red leaf mukdenia (Mukdenia rossii) – fanned, maple-like leaves emerge bright green in spring, age to bronze-green in summer, and finish green with bright red streaks in Fall. White bell-shaped flowers stand above the foliage in early spring. Use as a groundcover for woodland gardens, border edging, or add to mixed containers. (Zones 4-8)

Arkansas bluestar (Amsonia hubrichtii) – an erect, clump-forming perennial with clusters of 1/2 inch wide, 5-petal, powder blue flowers in late spring, feathery green summer leaves, and gradually turns golden yellow starting in late summer. Stems rise to 3 feet tall. Similar in appearance is Amsonia ciliata, minus conspicuous hairiness over the new leaves. (Zones 5-8).

Leadwort (Ceratostigma plumbaginoides) – 6-10 inch tall rhizomatous groundcover with blue flowers from late summer into Fall; clean medium green summer foliage turns bronze or red in fall. (Zones 5-9).

Autumn Fern (Dryopteris erythrosora) – glossy, copper-tinted new fronds emerge through the growing season into Fall; its frond color is perfect color for the Fall garden. (Zones 5-8).

Dwarf Variegated Solomon Seal (Polygonatum odoratum ‘Variegatum’) – 2-3 feet bright green elegant foliage that is splashed or streaked with white. Sweetly scented creamy white flowers form along its arching stems. Leaves turn an attractive gold color in Fall. (zones 3-8)

Muhlygrass (Muhlenbergia capillaries) produce loose, billowy inflorescences best described as pink clouds in early Fall. Pink muhly grows to 2.5 – 3 feet tall and 3 feet wide in flower. ‘White Cloud’ sports white flowers and grows more upright than pink muhly. New in 2022 was M. reverchanii Undaunted® that produces rosy pink floral sprays in early fall (USDA hardiness zones 6-10).

‘Black Mountain’ bluestem (Andropogon ternarius) varies across its natural range, growing up to 5 feet tall in some areas. ‘Black Mountain’ stays at 3 feet and under and grows more compact and refined than species. Flowering stems emerge bluish-green and develop reddish hues later in summer. Inflorescences (flower heads) have spikelets covered in silvery, white hairs. (Zones 6-9).

Several Varieties of Switch Grasses (Panicum virgatum) develop a great fall color. ‘Shenandoah’ – leaves develop rich black-burgundy tips in late summer; ‘Northwind’ – bright gold-streaked fall foliage; ‘Cheyenne Sky’ – dense, upright clump of blue-green blades turn wine red in early summer along with purple inflorescence in late summer. Leave switch grasses for winter interest. (Zones 5-9).

Feather Reed Grass (Calamagrostis x acutiflora) is a cool season plant and is one of the first ornamental grasses to emerge in spring and produces flowers and seeds early. Cultivars ‘Stricta’ and ‘Karl Foerster’ seed heads turn golden and shorter cultivar ‘Overdam’ turn tan in autumn. (Zones 4 – 9).

Swamp Hibiscus

Posted by Hugh on September 5th, 2023

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. Its 5- to 6-inch-long leaves are palmately lobed into 3, 5, or 7 parts. These finger-like lobes are slender and have jagged teeth along their margins. Deep red flowers are 5 to 6 inches wide appear in mid to late summer.; a white bloom form ‘White Texas Star’ is also available.

Plants are late starters calendar-wise. This herbaceous to semi-woody perennial dies back in the winter and returns in late May, generally following the emergence of (H. moscheutos).They’re fast growers and will reach 5-6 feet the first season. They can grow to be over 6 feet tall and may need staking, depending on their height and position. Swamp hibiscus bloom continuously, although blooms may last only 1-2 days. The plant also attracts butterflies, hummingbirds, and bees.

Swamp hibiscus is easily grown in the Mid-South (TN, NC, VA, KY, WV). Plant in locations with full sun to partial shade and with moist, occasionally wet soils. Propagation is through seed or stem cutting. This plant is slightly salt tolerant.

Flowers of swamp hibiscus appear in late summer to early fall and are large (up to 6 inches wide) and vibrant in color. Swamp hibiscus thrives in sunny, humid, and moist conditions. It grows well in loamy well-drained soils, but is equally at home in wet boggy sites, such as around a pond or 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. Deer may damage the brightly colored flowers.

Swamp hibiscus prefers hot and humid summers. If you garden in a northerly area, 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 seasonal rainfall is low. Avoid planting in a windy site.

In early spring fertilize with a 6-month slow-release formula like Osmocote or Nutricote. One pruning option to limit plant height is cut the previous year’s shoots down in late winter. Additionally, cut new spring growth back in early June (4-5 weeks after growth emergence) to encourage branching and lower overall shoots to 3-4 feet by summer’s end.

Plants may be damaged by stem canker, rust, leaf spots, aphids, and Japanese beetles. Swamp hibiscus will usually outgrow most injury by outgrowing these pests and present an attractive floral show. If grown partially shaded, tall plants may need staking.