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

Protect Your Home Against Artillery Fungus

Posted by Hugh on September 6th, 2020

Artillery Fungus/ Mulch near home foundation

If you notice tiny black specks covering your home or garage siding or coating your auto parked nearby. The problem may be artillery fungus, also called shotgun or cannonball fungus (Sphaerobolus). Tiny fungal spores, barely 2 millimeters wide, propel themselves up to 20 feet away from the ground onto vertical surfaces.

The fungus generally targets light surfaces such as vinyl siding or light colored vehicles. They are tiny black specks that don’t wash off with a coarse water spray from a hose. The “fungal dust” may also ruin your car’s finish.

Fungus activity most often occurs during cool rainy spring and fall days, particularly in shady areas. Look for it on the shady north side of your home. Artillery fungus stops producing spores when temperatures rise over 78°F, and is not as much a problem in the summer.

Landscaping with certain kinds of wood mulch creates the problem, but not all kinds of organic mulches are the source. Artillery fungal spores don’t cause any structural damage, but they may cosmetically stain vinyl siding — particularly if the spores have stuck onto surfaces for more than a few days. Don’t wait! With swift action, you may be able to power wash the spores off. Don’t use harsh cleaners or abrasives that might damage your home siding.

While the obvious solution may be to stop mulching, smart mulching is a better approach:

add a fresh layer of mulch around home foundations in the spring. Artillery fungus reproduces (sporulates) in old decayed mulch (or last year’s mulch).
Mushroom compost spread atop old landscape mulch will suppress artillery fungus sporulation by 40%.
Use large chunky pine bark (nuggets) around foundation plantings.
Instead of mulch plant low maintenance groundcovers near home foundations.
Replace wood mulch with landscape fabric and small stones.

Dyed wood mulch is not effective against the fungus.

Choices Of Inkberry Hollies

Posted by Hugh on September 1st, 2020

Inkberry holly (Ilex glabra), also called gallberry, is a slow-growing broadleaf evergreen shrub (USDA hardiness zones 4-9). Inkberry grows 5 to 8 feet tall. In the wild, it spreads in the ground via root suckers to form colonies. The species is native from coastal Canada to Florida, west to Louisiana at home in sandy woodlands and edges of swamps and bogs.

The dark green glossy leaves (to 1.5 inches long) have smooth margins and are spineless. Foliage stays attractive in winter unless temperatures dip below 0 °F. Greenish white flowers appear in spring, but are mostly inconspicuous. Jet black berry-like drupes (3/8 inch diameter) mature in early fall and persist throughout late winter into early spring unless consumed by birds and other wildlife.

Inkberry holly is undemanding. This durable shrub grows in average, medium to wet, acidic soils and in full sun to partial shade. It is one of few holly species that tolerates wet soils. Inkberries are separately sexed (dioecious), e.g. either male or female plants. Female plants accept pollen from a male plant to produce the berry-like fruits (called “drupes”).

Inkberry hollies are popular hedging shrubs the popular boxwood (Buxus spp.) look. Growth rate is greater than boxwoods and are not susceptible to the dreaded boxwood blight disease. Prune in early spring before new growth begins. Hollies need only minimal pruning unless used for hedging. Remove root suckers if undesired.

No serious insect or disease problems trouble inkberry hollies. Leaf spotting occurs in wet summers. Spider mites may appear, especially during dry weather. Leaf chlorosis (yellowing) may occur in alkaline (high pH) soils. When shopping for inkberry hollies, avoid varieties that become “bare-legged” or have “raise their skirts”. See list below

Inkberry Holly Varieties (Cultivars):

4 to 5 foot Category

‘Densa’ – 4 -5 feet high at maturity (with a slightly greater width)

‘Nordic’ – dark green foliage color and a distinct 5 foot tall broad pyramidal habit.

‘Shamrock’ – compact 5 feet high and wide, and densely branched.

2 to 3 foot Ultra-Dwarf Category

Gem Box® – new dwarf, dense ball-shaped form; small, dainty, dark green leaves with attractive red tips during the spring flush.

Strongbox® – very compact (2-3 feet tall), rounded form, densely branched with handsome evergreen evergreen hedge.

Mass or group several inkberry hollies as a shrub border, a low foundation planting. Species inkberries will naturalize in moist woodland gardens or near streams or ponds.

*Ilex glabra* ‘Strongbox’ (photo courtesy of Spring Meadow Nursery)

Many Kinds Of Deodar Cedars

Posted by Hugh on August 26th, 2020

Deodar Cypress

Deodar cedar (Cedrus deodara) on East TN State University Campus, Johnson City, TN

Himalayan cedar (Cedrus deodara), aka Deodar Cedar, is indigenous from northern India, east to Nepal, and northward through Pakistan and Afghanistan (USDA hardiness zones (6b)7-10). In the U.S., this evergreen conifer grows 60-70 feet high and 40 feet wide in 50 years. It offers year-round interest by way of its lovely pyramidal form and pendulous branching habit.

Deodar cedar is an excellent specimen tree. You may opt to mass several for privacy screening or a windbreak around your property. Create a unique focal point by clustering 3-5 trees together. Plant these long–lived evergreens for multi-generations to enjoy.

Site selection is most important. Deodars prefer mostly sunny sites and set in moist, well-drained soils. Two-year established trees are drought tolerant. Relatively free from pest and disease troubles, once planted, deodars will provide maintenance-free beauty.

Elegant weeping branches dip downward to the ground and then sweep upward. The older 2- and 3- year old needles drop in spring, just as new buds emerge to provide a soft green look. Male trees produce catkins that disperse copious amounts of pollen in early spring. Female trees develop 3-5 inch egg-shaped cones.

Weatherwise, deodars earn a reputation as finicky trees in the mid-South (Tennessee, Kentucky and Virginia). Young trees are more susceptible to cold than older stock. In a good soil young trees and shrubs grow off quickly, often achieving two feet of growth a year. If the tops of trees die back, winter freeze injury may be the problem.

Winter hardy tree forms include ‘Shalimar’, a selection made in the Kashmiri region of India and ‘Kashmir’. Many shrub forms are also available such as:
‘Feelin’ Blue’ – low spreading, mounding, space saving form; long, thick bluish tinted needles that retain their color into late summer; grows 1 to 2 feet tall in 10 years. ‘Glacier Blue’ -moderate growing shrub form with long blue-green foliage that grows 8-10 feet tall within 20 years.

Shrub-like ‘Glacier Blue’ at UT Gardens in Knoxville, TN

Perennials With Great Autumn Foliage

Posted by Hugh on August 21st, 2020

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 turns an attractive gold color in Fall. (zones 3-8)

‘Black Mountain’ bluestem (Andropogon ternarius) varies across its natural range, growing up to 5 feet tall in some areas. ‘Black Mountain’ has stayed at 3 feet or 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. ‘Stricta’ and ‘Karl Foerster’ develop reddish seed pods and ‘Overdam’ turns golden. (Zones 4 – 9).

Marginal Plants For Wet Areas

Posted by Hugh on August 16th, 2020

Brunnera macrophylla ‘Variegata’

‘Gateway’ Joe Pye

Most perennials demand well-drained soil. They perform poorly or die out when in ground that is constantly wet and soggy. However, a small number of perennials tolerate and even thrive in moist soils. Most plants listed here are all hardy within zones 5-8, and grow best in moist, humus-rich, well-drained soil. Most are okay getting their feet (roots and crown) wet for short time periods in terms of days, but not weeks. The list includes some ornamental grasses that cope with short period of flooding.

Bog plants, cannas, cardinal flower (Lobelia cardinalis), goatsbeard (Aruncus dioicus), monkshead (Aconitum), spiderwort (Tradescantia andersoniana), bugleweed (Ajuga reptans), flag iris (Iris pseudoacorus), Louisiana iris (Iris x hybrida) excel in a continuously wet spot around the water garden or a feature. Papyrus (Cyperus papyrus). Shrubs like weigela (Weigela floridus), kerria (Kerria japonica), Virginia sweetspire (Itea virginica), smooth hydrangea (H. arborescens), winterberry holly (Ilex verticillata), Joe Pye (Eutrochium spp.), and shrub dogwoods (Cornus spp.).

Perennials to look out for include: Hosta, Siberian bugloss (Brunnera macrophylla), Queen of the Prairie (Filipendula rubra), Toadlily (Tricyrtis formosana), loosestrife (Lysimachia clethroides), plume poppy (Macleaya), Chinese astilbe (Astilbe chinensis), black snakeroot (Cimicifuga racemosa), meadow rue (Thalictrum aquilegifolium), swamp sunflower (Helianthus angustifolius), obedient plant (Physostegia virginiana), swamp milkweed (Asclepias incarnata), calla lilies (Zantedeschia aethiopica), rodgersia (Rodgersia aesculifolia), primula, rose campion (Lychnus coronaria), Japanese iris (Iris ensata), Indian pink (Spigelia marilandica), ligularias (Ligularia spp.), Farfugium (F. japonicum), swamp hibiscus (Hibiscus coccineus), mukdenia (Mukdenia rossii), and some ferns including cinnamon fern (Osmundastrum cinnamomeum), royal fern (Osmunda regalis), arborvitae fern (Selaginella braunii), and sensitive fern (Onoclea sensibilis).

Ornamental Grasses for moist sites include hakone grass (Hakonechloa macra), sweet flag (Acorus gramineus), muhly grass (Muhlenbergia capillaris), sea oats (Chasmanthium latifolium), big bluestem (Andropogon gerardii), feather reed grass (Calamagrostis x acutiflora), switchgrass (Panicum virgatum), Bowles’ golden sedge (Carex elata ‘Aurea), Gray’s sedge (Carex grayi), Morrow sedge (Carex morrowii cv.), and common rush (Juncus effusa).

Six Architecturally Tall Perennials

Posted by Hugh on August 11th, 2020

Here are six showy architectural gems to grow in your garden. All six are “big guys” and are valued for their bold presence, disease-free foliage, and their attractive flowers, that are also great pollinators.

*Filipendula rubra* at Kingwood Center, Mansfield, Ohio

Queen of the Prairie (Filipendula rubra) is a U.S. native perennial that mimics an astilbe on steroids. This tall, upright, clump-forming perennial typically grows 6-8 feet tall and features branched, terminal, astilbe-like, 6-9 inch wide panicles (corymbs) of tiny, fragrant, pale pink flowers in early to mid-summer. Deeply cut, bright green, 4-8 inch long compound leaves are composed of 7-9 lobed lance-shaped leaflets. Leaves are fragrant when crushed. (USDA hardiness zones 3 to 8).

Bronze Fennel (Foeniculum vulgare ‘Purpureum’) is a highly aromatic perennial herb. Fennel is widely cultivated for its edible, licorice-flavored leaves and seeds. The variety ‘Purpureum’, also known as Bronze Fennel, has dark “smoky” foliage that is very attractive planted along perennial borders or in wide annual containers (staking necessary). You may opt to keep plants from blooming so they don’t reseed. However, the yellow flower heads are attractive. Specific swallowtail butterflies utilize bronze fennel as a food source for their caterpillars. (Zones 4 to 9).

Giant sunflower (Rudbeckia maximum) grow tall and bold. Huge basal powder blue leaves on giant stalks rise straight up bearing deep golden coneflowers. The central flower cones of “Rudbeckia max” grow 4-6 inches high. The old bloom stalks attract goldfinches for the seed (Zones 4 to 9).

Fall flowering sunflower (Helianthus angustifolium) is a narrow leaf perennial sunflower that will thrive in moist soil with full sun to part shade. Plants grow 5- 7 feet tall with cutleaf dark green foliage attached to maroon stems. An explosion of 2-3 inch wide yellow flowers comes in September into November. (Zones 6 to 9).

*Helianthus angustifolius* var. salicifolius

Scarlet Rose Mallow (Hibiscus coccineus) is a vigorous, woody-based 3-6 feet tall perennial. Stems bear showy 3-5 inch wide, 5-petaled, bright scarlet red flowers from mid-summer to early fall for a long bloom season. Palmately palmately compound, deep green leaves are very hemp-like, (5-6 inches wide). (Zones 6 to 11).

*Hibiscus coccineus* at NC Arboretum, Asheville, NC

Rosinweed (Silphinum spp.) is a native sunflower-like meadow plant. It typically grows on coarse erect stems to 4-8 feet tall and is identified by its square/quadrangular stems, coarsely-toothed foliage, and pairs of cup-forming leaves. Flower heads (to 3 inch diameter) feature light yellow rays (20-40) and darker yellow center disks bloom in summer on the upper part of the plant. Over wet spells, leaf cups collect dew and rain water. (Zones 4 to 8).

*Silphium* at NC Arboretum, Asheville, NC

Six Tall Architectural Statuesque Perennials

Celebrate Summerific® Rose Mallow (Hibiscus) Week

Posted by Hugh on August 6th, 2020

Perennial hibiscus (Hibiscus moscheutos) is commonly known as rose mallow or dinner plate size hibiscus. Blooms measure a huge 7-9 inches across. Plants are exceptionally hardy, and can withstand winters as cold as zone 4 (-20°F to -30°F) in Minnesota (zone 4) and the heat of zone 9 (20°F -30°F) in Florida. Each flower lasts only one day.

Summerific® Spinderella (Photo courtesy of Walters Gardens, Inc

Summerific® rose mallows are a huge improvement. Older varieties tended to produce flower buds only at the tips of the branches and bloomed for just a few weeks. Plants produced fewer flower buds.

Newer varieties in the Summerific series produce flower buds all up and down the stems, including the top. Newer Summerific varieties are bred to bloom for months, 3 times longer than older varieties.

Rose mallows need water and lots of it. Plants can actually grow in standing water. Grow them within reach of a hose or sprinklers and irrigate on a regular schedule. Whether you are growing in average soil or in a good garden loam, do not allow plants to wilt and dry out. Badly wilted plants will drop their lower leaves and flower buds.

Give them room to grow. Rose mallows are very robust growers that fill their space in the garden. Read the plant label about variety spacing. Dwarf varieties grow at least 3 feet tall and wide, and standard-sized rose mallows grow 4-6 feet tall and wide.

Bring on the sun. Full sun (6+ hours) is imperative. Dark leaf varieties develop a more intense dark purple foliage color in a sunny garden. Full sun equals more flowers. In partial shade, plants produce fewer flowers and dark leaf varieties appear more greenish.

Summerific® French Vanilla (photo courtesy of Walters Gardens, Inc)

Spring-Summer Perennial Hibiscus Care Tips:

Cut back rose mallow in the spring. Cut down the dormant woody stems to about 6 inches tall. Rose mallows tend to be one of the last plants to emerge, sometimes as late as early June in northern areas. Newly emerging shoots will grow rapidly, about an inch a day.
Once spring growth arises, sprinkle slow release plant food such as Espoma™ Plant-tone^® or an equivalent slow release organic fertilizer around the root zone (according the package directions. In early summer, follow-up with a water-soluble plant food like Miracle-Gro™ or Jacks™ just as flower buds are beginning to form.

Seven Late Summer Perennial Gems

Posted by Hugh on August 1st, 2020

‘Hot Lips’ turtlehead (Photo from North Creek Nursery, Landenburg, PA

The following seven (7) perennials provide gorgeous floral color in mixed perennial beds in late summer and into fall. Flowers attract pollinators, including lots of bees, butterflies, and an occasional hummingbird.

‘Blue Fortune’ Giant Hyssop (Agastache x ‘Blue Fortune’) offers lavender-blue flowers during a long hot summer extending into early fall. Leaves emit a minty-anise fragrance and adds flavor cold drinks. Dead-heading extends bloom time. Deer resistant. (USDA hardiness zones 5-9)

‘Little Spire’ Russian Sage (Perovskia atriplicifolia ‘Little Spire’) – compact and erect sub-shrub. It flaunts silvery aromatic foliage and striking light blue to violet floral color. This compact woody perennial grows only 2-3 feet high (versus the 6-7 feet tall species) and is drought tolerant. Deer Resistant. (zones 5-9)

‘Autumn Bride’ Heuchera (Heuchera villosa ‘Autumn Bride’) is a 2-foot-tall by 3-foot-wide native perennial that forms a dense mound of large fuzzy green leaves. The plant spreads by underground rhizome and holds up to moderate dry shade partial dry shade. Heucheras with villosa bloodline grow in either partial shade to full sun. Deer Resistant. (zones 3-8)

‘Hot Lips’ Pink Turtlehead (Chelone lyonii‘Hot Lips‘) produces attractive late-summer pink flowers that look like a turtle’s head. It prefers moist well-drained soils. This 2 to 3 foot-tall perennial has handsome dark green foliage. Deer Resistant. (zones 3-8)

‘Hillside Sheffield Pink’ Chrysanthemum – an old fashioned shrubby garden mum which grows 2-to 3 feet high and wide. Pinch in June to keep plants compact and bushy; divide plants every 2 or 3 years in spring to maintain vigor. Deer Resistant. (zones 3-8)

‘October Skies Aromatic Aster (Symphyotrichum oblongifolium ‘October Skies’) – one of our finest native asters. This 2-foot-tall by 2-foot-wide plant is covered up with dark blue flowers with yellow button centers. The plant forms a lush mound of foliage and should be pinched back by one-half in late June to develop a compact form. Deer Resistant. (zones 3-8)

Leadwort (Ceratostigma plumbaginoides), also called plumbago, is a low-growing dependable 8-10 inch high ground cover for sunny to partly shaded spots. Plumbago is filled with cobalt-blue flowers in late August; dark green leaves begin to turn red 4-5 weeks before abscising later in autumn. (zones 5-9)

General Care: all plants perform in partial to full sun and in well-drained soil. More sun means more flowers. All are moderately drought-tolerant after their first growing season. After blooming, plants don’t need to be cut back until late winter. For best look, set 3 or more plants in garden beds or containers.

Lovely Fruit Capsules Fill Sweetheart Tree In Late Summer

Posted by Hugh on July 26th, 2020

Korean sweetheart tree (Euscaphis japonica) is a large flowering shrub or small deciduous tree that is native to mountain valleys, open forests and thickets in China, Korea and Japan (USDA hardiness zones 6 to 8). Dr. J. C. Raulston discovered Korean sweetheart tree in 1985 on the Korean Peninsula during a plant expedition. Yet, it is still relatively unknown in American gardens. Sweetheart tree belongs to the bladdernut (Staphyleaceae) family

It typically matures to 12 to 20 feet tall, occasionally upwards to 30 feet and a spread of 8 to10 feet wide. Leaves are opposite pinnately compound, a single leaf 6-10 inches long. Each leaf is composed of 7-11 thick, leathery, finely toothed, glossy, dark green leaflets, 2-4 inches long. The deciduous leaves turn mahogany-purple hue in the fall.

This durable tree thrives in a variety of soils, preferably moist, for sweetheart tree to bloom and bear numerous fruits. The tree should be planted in partial to full sun. The yellowish-white flowers (each to 1/4” diameter) appear in spring (May-June) in 6-9 inch long terminal panicles and go by mostly unnoticed. It tolerates brief periods of drought, and performs best in moist soils. Avoid areas of the U.S. where summers are extremely hot and droughty.

The smooth purplish-brown gray bark is lined with white striations for winter interest. Its pinnately compound foliage displays an interesting textural character. The late summer fruits shaped like tiny heart-shaped red capsules, hence the name “sweetheart tree”.

Without question, plant collectors grow sweetheart tree for its showy clusters of heart-shaped fruits. Starting in early August, ripening fruits morph from green to pink to red. In early to mid-October capsules split open revealing a tiny, shiny, black seed. The jet black seeds hang from the tree branches. Wildlife attraction to the fruits is not known.

No serious insect or disease problems trouble this highly ornamental small tree. The tree is sold by specialty nurseries found on-line.

Korean Sweetheart Tree (*Euscaphis japonic*a)

Favorite Native Shrub Pollinators

Posted by Hugh on July 21st, 2020

These eight (8) shrubs amaze me by the numbers of bees and other pollinators that their flowers attract when blooming.

Virginia sweetspire (Itea virginica) is an erect, rounded, broad-spreading, deciduous shrub with arching branches. Itea grows 3-4 feet (less frequently to 5 feet) tall with similar spread. Fragrant, tiny white flowers borne in cylindrical, drooping racemes (3-6 inches long) cover the shrub from late spring to early summer. Oval, dark green leaves (1-4 inches long) turn varying shades of red, orange and gold in autumn. (USDA Hardiness Zones 5-9).

Elderberry (Sambucus canadensis) are known for their creamy white blooms against the glossy green foliage. Laceleaf and purple colored leaves are very ornamental. Elderberries attract great numbers of bees and other pollinators. They prefer a moist well-drained soil. (Zones 3-9).

Bottlebrush buckeye (Aesculus parviflora) spectacular 8-12 foot tall and 12-15 feet wide suckering summer flowering shrub in partial sunny areas; 8-12 inch white bottle brush flowers with showy red anthers and pinkish filament sand attractive dark green palmate leaves that turn bright yellow in the fall. (Zones 5-8).

Summersweet (Clethra alnifolia) grows 3-8 feet high. depending on cultivar. Sweetly fragrant white 2-6 inch long flower panicles attract hundreds of bees and butterflies in July. Flowers give way to dark brown seed capsules (1/8 inches diameter) which may persist into winter. Glossy dark green leaves (3-4 inches long) transition to shades of golden yellow in fall. (Zones 3-9).

Coralberries (Symphoricarpus spp.), represent several low ground cover shrubs. They produce tiny summer flowers which are browsed by many pollinators and fruits persist well into winter along arching stems. (Zones 2-7).

Bluebeard (Caryopteris spp.), aka blue mist shrub, is covered with brilliant blue blooms in late summer into fall and bees and butterflies come to them. (Zones 5-9).

Red Chokeberry (Aronia arbutifolia) grows 6-10 feet tall with spring blooms. Chokeberry grows in a stiff, upright vase shape habit and exhibits a fibrous rootsystem that suckers freely. Fruits are eaten by birds and other animals. (Zones 4-9).

Black chokeberry (Aronia melanocarpa) is another May blooming upright spreading, suckering shrub. It grows 3-6 feet tall with 5-6 flower clusters of white 5-petals which leads to tart, almost bitter black berries and purple/red fall leaf color in late summer. (Zones 3-8).