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

Prepare For Storm Damage

Posted by Hugh on November 22nd, 2021

A snow/ ice storm is both a beautiful and horrific scene in a landscape. Costly tree/shrub breakage, downed power lines, and subsequent utility shutoffs may be staggering results. Don’t feel powerless! Prepare and take action. During the storm, do nothing / “hands off”. Working near an active electrical line is deadly.

After the storm you should immediately assess the landscape damage. Contact your insurance agent and hire an ISA* certified professional arborist to fit your property into his/her schedule. After a storm, arborists are likely much too busy with emergency callers.

Inspect your trees BEFORE storms are predicted. First on your list should be those large trees not pruned in many years. Old trees are likely to shed diseased, pest ridden, and structurally weak limbs. Notorously weak wooded deciduous trees are silver maple (Acer saccharinum), sycamore or planetree (Platanus spp.), Bradford pear (Pyrus calleryana), poplars (Populus spp.), and willows (Salix spp.). They generally drop small twigs to large branches all the time. Large evergreens like white pine (Pinus strobus), Southern magnolia (Magnolia grandiflora) and leyland cypress (Cupressocyparis x leylandii) frequently loses branches and twigs during high winds and ice buildup.

Ironically, the trees suffering the worse damage are those topped by “Landscape Pros”, neighbors, and utility companies. The re-growths on topped trees are very weak and snap off when the snow and ice loads reach a critical mass. Properly pruned trees ride out most ice storms. Take care of your trees and trees will continue to beautify and cool.

2020 Evaluation of Russian Sages By CBG

Posted by Hugh on November 16th, 2021

Russian Sage (*Perovskia atriplicifolia*)

Russian sage (Perovskia spp.) is a popular garden and landscape plant valued for its lavender-blue flowers and long bloom period. Leaves are silvery green leaves. Long cultivated as an herbaceous perennial, Russian sage is technically a subshrub, a plant with a woody base that produces herbaceous stems. Perovskia spp. has recently renamed Salvia yangii and is a member of the mint family (Lamiaceae). Leaves and stems are pungently aromatic when crushed. Despite of its common name, Russian sage is not native to Russia, instead native to southwestern and central Asia.

Chicago Botanic Garden (CBG) (USDA Hardiness Zone 5b, AHS Plant Heat-Zone 5) recently completed an eight-year comparative trial of Russian sages in October 2020. Five cultivars earned five-star excellent ratings for their superior floral displays and consistently strong habits: Blue Spritzer, ‘Blue Jean Baby’, ‘Blue Steel’, ‘Little Lace’, and ‘Denim ‘n Lace’.

Russian sages are prized for their fuzzy lavender-blue flowers and silvery-filigreed foliage on upright, sturdy stems from mid-July to mid-October.
Most new introductions are chosen for their shorter, more compact habits. Bees and other insects were constant visitors during the long bloom period. No diseases or pests trouble this low maintenance perennial. Foliar chlorosis was a minor issue observed on all varieties, observed in high pH soils.

‘Blue Spritzer’ (‘Balperobritz’) has a bushy, vase-shaped habit—30 inches tall and 36 inches wide along with lighter lavender-blue flowers on airy spires and purple calyces. Blue Spritzer featured egg-shaped, silvery green leaves with entire margins; some leaves are occasionally serrated.

‘Blue Jean Baby’ is a compact bushy variety just under 30 inches tall and 32 inches wide. From early July to October, a profusion of lavender-blue and purple flowers; sage green, deeply dissected leaves.

‘Blue Steel’ is a seed cultivar that compared favorably to vegetative cultivars; 32 inches tall and 34 inches wide; airy dark lavender-blue flowers from July into mid-October; ovate, bluntly serrated green leaves with wavy margins and citrus-scented.

Little Lace (‘Novaperlac’) provided an impressive flower show from early July into early October; compact bushy plants—32 inches tall and 38 inches wide; deeply incised gray-green leaves and airy lavender-blue flowers.

‘Denim ’n Lace’ flaunt densely clustered, upright sky blue flower panicles from mid-July to mid-October; above high pollinator activity; 33 inches height and 48 inches width.

Read the entire research report on the Chicago Botanical Garden website.

Enormous Leaves On Sapling Trees

Posted by Hugh on November 11th, 2021

Some fast-growing trees like Royal Empress tree (Paulownia tomentosum) smoketree (Cotinus coggygria), and basswood linden (Tilia americana). There are lots more arboreal candidates. Keep the young tree saplings vegetative by practicing “Renewal Pruning”.

To create an accent tree, single or multi-stemmed, wait until the plant has been in the ground for a few years, then begin to limb up the shrub. Select one to three stems that will become the dominant 1 or more trunks of your small tree and remove all other branches. Continue to shape this way until you arrive at the desired look. Again, snip off lower and interior branches that may develop.

Several Cotinus cultivars produce colorful seasonal foliage such as: ‘Royal Purple’ has burgundy foliage that changes to brilliant red in fall; ‘Grace’ struts huge, maroon leaves and deep salmon pink fall color; ‘Golden Spirit’ (Ancot) has chartreuse leaves that turn yellow in autumn.

If your goal is colorful foliage, cut the stems back garden in winter to 6 to 8 inches. The following spring enormous size leaves develop on vigorous growth from the ground. This is classified as hard pruning or renovation pruning and can be done every year. Just cutback last year’s woody shoots and start over. Fertilize annually and irrigate during long summer dry periods.

Plants That Attract Birds To Your Property

Posted by Hugh on November 6th, 2021

Birds visit trees, shrubs, vines and perennials for five things: fruits (berries), sweet nectar (flowers), insects (particularly caterpillars), nuts and seeds, and shelter. This list is a compilation from the North Carolina and Tennessee chapters of the Audubon Society of ornamental plants common in the Southern Appalachian region.

Trees and Shrubs

Maples (Acer spp.)

Downy serviceberry (Amelanchier arborea)

River Birch (Betula nigra)

Beautyberry (Callicarpa americana)

Hickories (Carya spp.)

Dogwood (Cornus florida)

New Jersey Tea (Ceanothus americanus)

Hawthorns (Crataegus spp.)

Winterberry (Ilex verticillata)

Virginia Sweetspire (Itea virginica)

Eastern Red Cedar (Juniperus virginiana)

Spicebush (Lindera benzoin)

Sweetbay Magnolia (Magnolia virginiana)

Crabapples (Malus spp.)

Blackgum (Nyssa sylvatica)

Pines (Pinus spp.)

Wild Plum (Prunus americana)

Cherries (Prunus spp.)

Sweet Azalea (Rhododendron arborescens) – at higher elevations

Pinxterﬂower (Rhododendron periclymenoides)

Oaks (Quercus spp.)

Wiilows (Salix spp.)

Elderberry (Sambucus canadensis)

Sassafras (Sassafras albidum)

Arrow-wood Viburnum (Viburnum dentatum)

Smooth Witherod (Viburnum nudum)

Woody Vines

Trumpet-creeper (Campsis radicans)

Cross-vine (Bignonia capreolata)

Coral honeysuckle (Lonicera sempervirens)

Perennials

Columbine (Aquilegia canadensis)

Butterfly weed (Asclepias tuberosa)

Green and Gold (Chrysogonum virginianum)

Lobed Tickseed (Coreopsis auriculata)

Threadleaf Coreopsis (Coreopsis verticillata)

Star Tickseeds (Coreopsis pubescens var pubescens)

Joy Pye weed (Eutrochium maculatum)

Cardinal Flower (Lobelia cardinalis)

Wild Bergamot (Monarda fistulosa)

Wild Quinine (Parthenium integrifolium)

Beardtongue (Penstemon)

Eastern Blue Phlox (Phlox divaricata)

Trailing Phlox (Phlox nivalis)

Moss Pink (Phlox subulata)

Creeping Phlox (Phlox stolonifera)

Black-eyed Susans (Rudbeckia fulgida var fulgida)

White Wood Aster (Eurybia divaricata)

Wreath Goldenrod (Solidago caesia)

Large ﬂower Aster (Symphyotrichum grandiﬂorum)

Smooth Blue Aster (Symphyotrichum leave)

Eastern Aromatic Aster (Symphyotrichum oblongifolium)

Iron Weed (Vernonia lettermanni)

Ornamental Grasses

Switchgrass (Panicum virgatum)

Little Bluestem (Schizachyrium scoparium)

Yellow Indian Grass (Sorghastrum nutans)

Hawthorn Trees In The Landscape

Posted by Hugh on November 1st, 2021

The world of hawthorns (Crataegus spp.) includes several outstanding landscape trees that exhibit four-season ornamental interest: 1. spring flowering, 2. disease-free summer foliage, 3. variable fall leaf color, and 4. colorful fruits for wildlife in the fall and winter months. World-wide, hawthorns are native to temperate regions of North America, Europe, Asia, and North Africa, and belong to the Rose family (Rosaceae).

Trees develop a dense canopy of crossing branches with glossy lobed leaves. Most species produce thorns, although some thorn-less forms are available. Hawthorns grow in a wide variety of soils and growing conditions, and make good landscape trees or street tree. Some hawthorns are ideal for planting under power lines and are commonly utilized for tall hedging on large properties, particularly on European estates.

Spring bloom on Cockspur hawthorn (*Crataegus crusgalli*) Note the 3″ long thorns!

Fragrant white or pink five-petaled flowers resemble apple blossoms. Hawthorn fruits, which look similar to rose hips, are red, orange, yellow, or black. The fruits are produced in fall and persist through winter. The edible fruits (called “pomes”) have various culinary and medicinal qualities, and attract various wildlife, including robins, waxwings, and other songbirds.

Most hawthorns, particularly those that produce thorns, are fairly deer resistant. Hawthorn trees are planted from spring into early fall in full sun and a well-drained soil with a moderately acidic soil between pH 6.0 to 7.5. Water newly planted trees through their first growing season until established.

Once established, Hawthorns are a good choice for curbside, public plantings, and some difficult landscape sites. Water regularly during the first year and during prolonged heat or dry spells. Overwatering and poorly drained soil will lead to foliar and root rot diseases.

Hawthorns are generally light constantfeeders. In early spring, apply a slow-release fertilizers like Osmocote™ or Nutricote™. Mulch with a layer of compost, pine needles, or bark chips to conserve moisture and suppress weeds.

When pruning, use caution to avoid injury from thorns on prickly varieties. Wear heavy gloves, long sleeves, and goggles to protect your eyes. In late winter or early spring, remove damaged, diseased, or crossing branches and shape as needed. Cut back any suckers around the base of the trunk.

Good cultural practices should avoid or lessen disease and pest problems including fire blight, leaf spots, cedar hawthorn rust, apple scab, powdery mildew, and stem cankers. Potential pests include borers, caterpillars, lacebugs, gall mites, aphids, leafminers, and scale.

Three popular hawthorn species/varieties in U.S. landscapes:

Washington hawthorn (C. phaenopyrum) is a southeastern U.S. native, 20-30 feet tall and 20-25 feet wide with an upright spreading habit. Leaves are glossy with pointed lobes and serrated edges. Clusters of pungent white flowers appear in late spring and bright red fruits appear in fall. Sharp thorns make this a good choice to prune into a security hedge (zones 3-9). Fall foliage is brilliant scarlet, orange, and purple.

‘Winter King’ green hawthorn (C. viridis) is a southeastern U.S. native that is a popular landscape and street tree that grows 20-30 feet tall and wide. Fragrant white flowers bloom profusely in mid spring, medium green foliage turns purple-red in fall. Showy red fruits form in fall and persist through most of winter. The silver-gray bark peels off as it ages, revealing its orange inner bark for added winter interest. Branches are nearly thornless, along with disease-resistant foliage. (Zones: 4-7).

Crusader® (syn. ‘Cruzam’) cockspur hawthorn (C. crus-galli var. inermis) is a thornless cultivar. The parent species bears 4 inch long thorns. Crusader is tough as nails, 15-30 feet tall and wide with wide spreading horizontal branching. White spring flowers, green summer foliage, red fruit, silvery bark; variable colored fall foliage of orange, scarlet and purple leaves. Large red fruits stand out against the tree’s spectacular fall foliage. Disease-resistant, very adaptable and tolerant of urban pollution, clay soil, and salt. (Zones:3-7).

Perennials With Great Autumn Leaf Color

Posted by Hugh on October 27th, 2021

Arkansas bluestar (*Amsonia hubrichtii*) fall color

In addition to foliage changes seen in landscape trees and shrubs, a select number of perennials contribute to the autumnal leaf colors. Here is a select list of popular perennials endeared for their autumnal foliage hues.

Arkansas bluestar (Amsonia hubrichtii) – stunning golden foliage beginning in late September.

Bloody cranesbill (Geranium sanguineum) – geranium ground cover with reddish purple foliage color in October; Geranium x ‘Rozanne’ foliage develops a bronze-red tint; G. macrorrhizum ‘Ingwersen’s Variety’ – mixed foliage turns an attractive red color in fall.

Jacob’s ladder (Polemonium ‘Bressingham Purple’) turns royal purple foliage in spring and fall; summer foliage is vibrantly green.

Ferns (selected ferns) – Autumn fern (Dryopteris erythrosora), Royal fern (Osmunda regalis); Sensitive fern (Onclea)

Selected forms of sedums (Sedum spp.) develop yellow and orange shades in fall. example: S. rupestre ‘Angelina’

Bronze-leaf rodgersia (Rodgersia podophylla) takes on coppery red and yellows shades in the fall; annual fall color is highly variable.

Dwarf Variegated Solomon seal (Polygonatum odoratum ‘Variegatum’) is rarely recognized by gardeners.

Leadwort (Ceratastigma plumbaginoides) – low mounding groundcover awakens very late in spring. Deep green leaves develop splashes of red in fall. Blue, starry flowers bloom in late summer into fall.

Herbaceous Peony (Paenonia lactiflora) – fall color is iffy among peony varieties; some may turn rusty orange lasting a week or more.

Golden aralia (Aralia cordata ‘Sun King’) – golden foliage hangs on through October.

Ornamental grasses (Miscanthus sinensis); Japanese bloodgrass (Imperata cylindrica); pink muhly grass (Muhlenbergeri capillaris) or white M. capillaris ‘White Cloud’ inflorescences; foliage of assorted sedges (Carex spp).

Several forms of switchgrass (Panicum virgatum) – ‘Northwind’ (autumnal yellow leaf blades), ‘Shenandoah’ (reddish tones in leaf blades), ‘Cheyenne Sky’ (dark maroon leaf tips)

Bellwort, merrybells (Uvularia perfoliata) – fall leaf color lasts 7-10 days.

Tips On Overwintering Outdoor Containers

Posted by Hugh on October 21st, 2021

Containers filled with shrubs and perennials, doesn’t necessarily ensure their winter survival. Without adequate cold protection plants may succumb to cold injury—turning them into dead annuals.

Heath (*Erica x darleyensis*) enjoys cool winters (zones 6-8)

To over-winter perennials in containers, you need to know their root and shoot temperature hardiness. Often, plant hardiness ratings is listed on the label.

Roots and shoots of several landscape plants have different hardiness levels. For example, above ground potted landscape species such as hollies, azaleas, and boxwoods may be winter hardy at 5-10 °F, yet their roots are injured below 18-20 °F. Day to day air temps may fluctuate wildly and the plant crowns and roots are much more sensitive to temperature swings than their above ground branches.

Here are several helpful pointers to improve the survival of containerized plants during the winter months:

Taxus (yew) hedge may be injured by late fall pruning

Grow Two Zones Colder. When growing perennials in containers, select those that are rated two plant zones hardier than your own.
Transplant Into Larger containers. Large containers contain more soil and offer greater winter protection to roots than smaller pots can provide. Also, line pots with styrofoam insulation
Huddle for warmth. Group multiple containers tightly together and move them in a wind protective corner of the garden. In some climates, they may also be beneficial to cover them with loose leafy mulch to added temperature protection as well as fluctuation.
Dig Pots In. Container roots can be protected from cold if you trench pots into the ground. Dig a hole or pit in the ground and take advantage of the heat and insulation that the earth provides.
Bring Them Inside. Set the containers inside a shed or an unheated garage to protect temperamental perennials, such as elephant ears, cannas, crinums, blue mist shrub and butterfly bush (Buddleia x davidii) (USDA Zones 5–9).
Delay pruning back some tender shrubs in the fall. Buddleias, crape myrtles, and bluemist shrub (Caryopteris) are examples.
Late fall clipping of hedges, such as hollies, yews, boxwoods, or privets, may be injured if winter temps turn out to be unusually severe in your region.

Forms of Western Arborvitae

Posted by Hugh on October 16th, 2021

Here is a partial listing of cultivars of Western arborvitae (Thuja plicata), as found in the U.S. nursery industry. Several are good choices for dwarf conifer collectors, in rock gardens, and in large containers. Winter hardiness of some cultivars is variable. Note: some are dwarf forms of ‘Green Giant’ arborvitae (Thuja standishii x plicata) which is a hybrid form.

‘Can-Can’ – semi-dwarf, dense, upright tree habit, 8 feet high and 5 feet wide in 10 years; dark green foliage with golden-white tips. (zones 6-9).

‘Excelsa’ – up to 35 feet tall with 20 feet spread; bright green fan-like foliage rated as fragrant. (zones 7-10).

‘Grune Kugel’ – ultra-dwarf slow growing dense mound 12 – 18 inches tall, 18 – 30 inches wide. (zones 5-8).

‘Hogan’ – medium-size columnar grower (40 feet x 20 feet) with dense narrow habit (sometimes mislabeled ‘Fastigiata’). (zones 5-7).

‘Junior Giant’ – about 40% to 50% the size of Thuja ‘Green Giant’ (about 20 to 25 feet tall and 10 feet wide). Branches seem to be held more horizontally. (zones 4-8/9).

‘Pygmaea’ – irregular upright branching; 2-3 feet shrub in 10 years. dense, blue-green foliage, tips may turn bronze in winter. (zones 5-8).

‘Rogers Aurea’ – reaches 4 – 5 feet high and wide with an oval to globose growth habit; decidedly smaller compared to the standard ‘Aurea’ with a broad pyramidal habit; bright golden yellow foliage outwardly, greenish on inner wood. Needles turn gold/orange-ish/bronze color in winter (depending on severity). (zones 5-9).

‘Stoneham Gold’ – dwarf form to 7 feet tall, compact, upright habit; branch tips are golden-yellow. (zone 7).

‘Sunshine’ (also may be ‘Canadian Gold’) – 40 – 70 feet tall, with bright gold needles that reportedly turn off bronze in winter. (zones 5-9)

‘Virescens’– slightly narrower habit, 20-30 feet tall and 9-12 feet wide. Glossy, dark green foliage holds its green year round without winter bronzing.

‘Whipcord’ – shrubby, slow-growing, dwarf form with pendulous whipcord-like green foliage; 2-3 feet tall and wide in 10 years, ages to 4-5 feet; scale-like leaves may turn coppery-bronze in fall. (zones 5-9)

‘Zabrina’ – large tree form, 40 feet at maturity, with broad, pyramidal habit; variegated foliage, specially for its bands of green and golden-yellow. (zones 5-7).

Possum Haw Holly

Posted by Hugh on October 11th, 2021

Possum haw (Ilex decidua) is a deciduous holly, grown as a large shrub or small tree. Its colorful winter berries brighten woodlands along creeks and rivers in the Midwest and Southeastern U.S. (USDA hardiness zones 5 -9). It is known by a number of common names, including bearberry, winterberry, deciduous holly, among others. Its popular name “possum haw” comes from the fact that opossums feed on its fruits.

As a shrub possum haw grows 8 feet to 15 feet high and 8 feet to 10 feet wide. Tree forms grow 18-25 feet tall, depending on cultivar. It may be utilized it as a single fruit-bearing female specimen plant if a male pollinator shrub is nearby. Or plant several for a deciduous privacy hedge or screen.

Small white flowers open in late April in Tennessee and Virginia (USDA hardiness zones 6 -7). Based on the cultivar grown, colorful berries may be crimson, scarlet, orange, gold or yellow.

Plant the appropriate male pollinating variety among many fruit bearing females to insure a bountiful crop of colorful berries from mid-autumn thru the winter months which attract wildlife (see below).

White flowers open in late April in the Southern Appalachian region. Possum haw has an attractive branching habit and gray bark. The 1½- to 3-inch long oval leaves are glossy dark green in summer and transition to a rich yellow fall color before abscising.

Various forms – from weeping to upright – and with other fruit colors are being developed and introduced. Florists are utilizing heavily fruited branches in decorating; the fruits persist for many weeks. Few serious disease and pest problems trouble this shrub.

Possumhaw can be found on limestone glades and bluffs, along streams in wet woods, and in lowland valleys, sloughs and swamps. It is an upright shrub or small tree with a spreading, rounded crown. Its bark is gray-brown and smooth with occasional warts. Birds, deer and a variety of small mammals (including opossums as the common name suggests) are attracted to the fruit. Prune to shape in early spring just before new growth begins.

‘Council Fire’ is a female plant and needs a male pollinator (e.g., male Ilex decidua or Ilex opaca ‘Jersey Knight’) for berry production. One male plant is usually adequate to pollinating 9-10 female plants.

‘Raritan Chief’ – a male clone used to pollinate many deciduous holly hybrids, as it flowers over a long period. It may reach 12 feet tall and features attractive glossy, light green foliage.

Additional Varieties:

‘Byer’s Golden’ – 8-10 feet shrub; gold fruits
‘Council Fire’ – 15 feet high; persistent orange-red fruits
‘Red Escort’ – 18 feet high; male pollinator
‘Pocahontas’ – 7 feet; bright red berries
‘Sentry’ – 18-20 feet high; red berries
‘Sundance’ – 7 feet tall; orange-red berries
‘Warren’s Red’ – 12-18 feet tall; bright red

Coral honeysuckle

Posted by Hugh on October 6th, 2021

Coral honeysuckle (Lonicera sempervirens), aka trumpet honeysuckle, is a vigorous twining flowering vine that is primarily native to the southeastern U.S. (USDA hardiness zones 4 -8). Cultivars are available in shades of red, orange. and yellow. The colorful flowers appear in spring and summer, and colorful berries decorate in late summer and autumn. Invite hummingbirds to your patio via a decorative trellis or pergola.

Coral honeysuckle prefers partial to full sun, and is best grown in fertile, humus-rich, moist, well-drained soil. In early spring, fertilize with a general-purpose granular fertilizer such as 10-10-10 or 19-19-19. Too much fertilizer stimulates lush foliage and less flowers. Coral honeysuckle is a drought-tolerant vine. Moisture stress may decrease blooming. Mulch annually around the plant to conserve soil moisture.

Coral honeysuckle is a twining vine that needs a sturdy climbing support such as a trellis, arbor, or fence. Flowers originate on new growth, so most pruning activity should be postponed until fall or winter seasons.

Prune this vigorous vine annually to rein-in its vegetative vigor and maximize its flower power. Unpruned vines eventually decline in growth and blooms are fewer and many are deformed. Remove one-third of the vine’s old growth annually, cutting the vines back to the main stem. Pruning is best done in late winter. You may rejuvenate an overgrown unproductive vine by cutting it clear to the ground. When new growth returns, regular pruning will keep it looking healthy and tidy.

Pest or disease problems are a rarity, although powdery mildew and leaf spots may pop up in a hot humid summer. Inspect for honeysuckle aphids, particularly during cool, wet spring periods.

Cultivars: Favorites are ‘Major Wheeler’ (non-stop showy clusters of orange-red flowers, ‘Dropmore Scarlet’ (hybrid form with red flowers), ‘John Clayton’ (yellow-flowered, rebloomer), ‘Sulphurea’ (yellow-flowered). Yellow-flowered L. flava is native to the Ozarks.