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

Deciduous Trees With Yellow Fall Leaf Color

Posted by Hugh on October 6th, 2020

While there are numerous trees that offer wonderful yellow fall foliage, some make extraordinary specimens in residential and park landscapes. Enjoy the beautiful yellow and gold tones on a crisp fall day. Caveat: the quality of fall color may vary from year to year.

Big-leaf maple (Acer macrophyllum) – this West Coast Native grows 60-75 feet tall tree with huge leaves that turn a rich shade of yellow in autumn, many times with a hint of orange. Zone 5-9.

Ohio buckeye (Aesculus glabra) – small- to medium-sized tree produces yellow fall foliage, but the leaves sometimes are red or orange, depending on weather conditions. Zones 3-7.

Serviceberry (Amelanchier x grandiflora) – small, showy spring flowering native with variable yellow to orange-red fall color. Zones 4-9

Pignut hickory (C.arya glabra) –this tap-rooted large 50-60 feet tall woodland tree in the eastern and Midwest U.S. exhibits above average golden yellow-brown fall color. Zones 4-8.

Shagbark hickory (Carya ovata) –shagbark hickory’s colorful foliage that turns from yellow to brown as autumn progresses; known for its shaggy bark and flavorful nuts. Zones 4-8.

Katsura tree (Cerciphyllum japonicum) – large 50-60 feet tall, rounded tree that produces purple, heart-shaped leaves in spring with apricot-yellow fall foliage. Zones 5-8.

Eastern redbud (Cercis canadensis) – native spring flowering famous favored for its rose-purple flowers and attractive, greenish-yellow fall foliage. Zones 4-8

Green ash (Fraxinus pensylvania) – pinnately compound foliage turns yellow in fall, with quality of the fall color often varying considerably from year to year. (Zones 3-9).

Ginkgo (Ginkgo biloba) – aka maidenhair tree, develops an attractive, fan-shaped foliage that turns bright yellow in autumn. Zones 3-8.

Larch (Larix spp.) – Available in a range of sizes and forms, larchis a deciduous evergreen tree that grows in cold, mountainous regions. Fall foliage is a shade of brilliant, golden-yellow. Zones 2-6.

Tulip poplar (Liriodendron tulipifera) – aka yellow poplar, this huge, tall tree is actually a member of the magnolia family. It is one of the prettiest, most majestic trees with yellow fall leaves. Zones 4-9.

Persian ironwood (Parrotia persica) – small to medium tree that produces a range of sunset colors, including variable orange, red and yellow fall foliage. Zones 4-8.

False larch (Pseudolarix amabilis) – this deciduous conifer from China is rarely seen in U.S. landscape; grows 30-60 feet tall and never fails to provide a wow! golden to bronze leaf color in October, often lasting 2+ weeks. (Zones 4-7).

False Larch (*Pseudolarix amabili*s) at the NC Arboretum in Asheville, NC

Fall Clean Up Of Garden Beds

Posted by Hugh on October 1st, 2020

Cleaning up vegetable and flower beds requires some thought. Most gardeners desire to get a start on next spring’s clean up in the fall. They may rototill garden beds in fall, particularly if soils are too moist to work in early spring. Turning the soil also kills lots of weeds, including winter weeds which have already already germinated and have been growing through the winter months.

Cut back almost all plant debris: spent flowers, stalks, anything dead. Tender perennials such as pampas grass, lavender, and rosemary should not be pruned back until spring. However, bearded irises benefit being cutback in the fall as the larvae of iris borers make their winter home in the garden debris.

In early fall, use Preen® weed preventer to suppress cool season weeds from sprouting in garden soil. Weeds like chickweed and henbit germinate in the fall, and put on a growth explosion during the mild days of February and March.

Lay a thin layer of mulch over the perennial beds, just an inch or so, to protect any flower bulbs, perennial roots like calla lilies, and prevent soil loss on slopes and tempermental perennials like angel trumpets (Brugmansia), cannas, and elephant ears

Once the garden bed is cleaned up and free of debris, fall is a good time to test your garden soil to prepare for a great growing season come spring. Every 4-5 years, have your soil analyzed to check the pH level and nutrient content. In the spring you will know how much fertilizer to add. Your local Extension Office will offer this soil testing service for a fee.

Based on the soil report, if the soil pH is too acidic, add limestone; too high pH (alkaline), add elemental sulfur or gypsum to increase soil acidity. Independent garden centers and farm supply stores are good places to buy limestone or sulfur to apply in the fall. Winter precipitation and cold temperatures will break down lime and sulfur. Soil pH levels should be adjusted by the time spring arrives

Lastly, take a few minutes in the fall to write down your garden successes and failures over the past growing season. This will help you to plan next year’s garden. New flower or vegetable catalogs will be arriving to the mail.

EXTRA: If you plan to feed birds and other wildlife in winter, do not cut back the seed heads of certain perennials and annuals such as: coneflowers (Echinacea), blackeye Susans (Rudbeckia), globe amaranths (Gomphrena) and zinnias.

Tips On Growing Fern Leaf Peony

Posted by Hugh on September 26th, 2020

Fernleaf peony (*Paeonia tenuifolia*i) -photo courtesy of Hollingsworth Peony Farm

Fernleaf peony (Paeonia tenuifolia), sometimes called “fennel peony”, is recognized principally for its finely dissected foliage. When properly sited and cared for, it is a low maintenance perennial. This uniquely different peony is native in parts of Eastern Europe (USDA hardiness zones 4 – 8).

Peonies perform best in well-drained, evenly moist, compost rich soil with a pH near neutral. Plants usually fail in clay soil unless it has been generously amended with compost. Plants become drought-tolerant after one year in the garden. Site fern leaf peonies in full to partial sunlight and in average to moist soil that is well-drained. Never allowed plants to dry out and avoid dry windy sites.

Fernleaf peonies are treasured by peony connoisseurs and rare plant collectors. Leaves are susceptible to leaf spot and mildew diseases. Do not overhead irrigate fern leaf types to prevent foliar disease outbreaks. Deer generally leave peonies alone. They’re tolerant of urban air pollution. Plants are propagated by division.

At the start plant growth may be slow, but fernleaf peonies are long-lived, some over 25 years when properly sited and annually cared for. Set the thick fleshy roots below the soil with the buds (eyes) 1.5 to 2 inches below soil level. Plants barely stand 18 to 24 inches tall and 24 inches wide. The 2 1/2- to 3-inch, bright red flowers bloom in late summer have very short stems and they appear to sit directly on the foliage.

In southern climes (GA, FL, AL, MS), protect their delicate finely cut foliage from drying afternoon sun and from high winds. Floral stalks may be weak if planted in excessively rich soil or too much shade. Some may require caging or staking soon after shoots emerge in spring. Fernleaf peonies tend to go dormant in mid-summer.

Water fernleaf peonies often enough to keep the soil moderately moist. Feed fern leaf peonies with a mixture of bone meal and either compost or well-rotted manure in early fall before the foliage fades. If you opt to use a commercial fertilizer, choose one with a lower percentage of nitrogen (N) than phosphorous (P), and potassium (K) or a 1:2:1 ratio. High levels of nitrogen lead to fewer flowers.

Double Fernleaf (‘Rubra Plena’) peony features bold lightly-scented dark red flowers at the ends of the stems from late spring to early summer. Flowers are suitable for cutting.

Fernleaf peonies are more expensive that most herbaceous types. Plants are available from online nurseries and specialty peony nurseries.

Fall Color Of Ornamental Grasses

Posted by Hugh on September 21st, 2020

Muhly Grass (Muhlenbergeri capillaris) grows 3-4 feet with blemish-free green foliage all summer long. By early fall, its bright colored floral seed heads (inflorescenses) are showing up, which gives Muhly its decorative look. ‘Pink Muhly’ tends to grow floppy and struts pink-hued inflorescenses that shimmer in a breeze. ‘White Cloud’ is a white flowering form of muhly that stands more upright. (USDA Hardiness Zones 7 – 11).

Many switch grass (Panicum virgatum) develop great fall leaf color. In summer, the leaf blades of some switch grass varieties develop showy red-stained tips. ‘Shenandoah’ blades turn rich black-burgundy; ‘Northwind’ – bright gold streaked fall foliage; ‘Cheyenne Sky’ – dense, blue-green blades turn wine red in early summer and purple inflorescence appear in late summer (zones 5-9).

Big bluestem (Andropogon ternarius) varies across its natural range, growing as high as 5 feet tall in some areas. NC selection ‘Black Mountain’ stays 3 feet or under, and grows more compact than the species. Flowering stems emerge bluish-green and develop reddish hues later in summer. The inflorescences are composed of spikelets covered in silvery, white hairs.(zones 6-9)

Fountain grasses (Pennisetum spp.) represents a huge selection of both annual (P. setaceum) or perennial (P. alopecuroides) fountain grasses. Among the perennial varieties are: 1. ‘Rubrum’ holds its red color all season; 2. ‘Moudry’ has spring-summer green foliage that turns golden yellow foliage and burgundy red foxtail plumes in fall; 3. ‘Fireworks’ (annual) is highly colorful through most of the season.

Feather Reed Grass (Calamagrostis x acutiflora) is a cool season plant that is one of the first ornamental grasses to shoot up in spring. It also is one of the first to go to seed. ‘Stricta’ and ‘Karl Foerster’ have reddish seed pods and ‘Overdam’ turns golden. (USDA Hardiness Zones 4 – 9)

Prairie Dropseed (Sporobolus heterolepis) has thin, airy leaves that create a weeping habit. In cool fall weather and ample soil moisture, the leaf blades turn almost pumpkin orange (Zones 3 – 9).

Blackgum (Tupelo) – Fall Leaf Color And Fruit Attract Birds And Other Wildlife

Posted by Hugh on September 16th, 2020

Black tupelo, blackgum, or sourgum tree (Nyssa sylvatica), its three common regional names, is native to Eastern North America from the New England states, down south into Florida, and as far west as Eastern Texas (USDA hardiness zones 4-9). Mature blackgums reach heights of 60 feet and taller and 20 – 25 feet width that grows into a lovely landscape shade, lawn or street tree.

In the wild, blackgum is typically found growing in low boggy ground subject to periodic flooding. It prefers moist loamy well drained soils, but adapts to most landscape sites. Newly planted seedling trees often start off slowly their first year after planting because sapling trees produce long taproots. However, modern-day nursery practices have solved the taproot issue and blackgums grow as fast as sugar maples (Acer saccharum).

This lovely shade tree is grown for its glossy dark green summer foliage and scarlet red fall color. Early spring flowers are not very noticeable, but are an important nectar source for bees. Tupelo honey is also highly prized.

Black tupelo has a mostly dioecious flowering trait. The small greenish-white flowers appear in spring on long stalks and attract nectar hungry for bees. Some trees bear male flowers while others produce mostly female flowers. A tree with mostly pollinated female flowers will be loaded with ripened bluish black berries that birds and other wildlife will devour in the fall.

Young trees develop a pyramidal and branch form and develop a broad open canopy with age. Lower branches on mature trees tend to be pendulous. The rugged dark bark on older trees is blocky, similar to an alligator’s hide.

Seedling and some cultivar forms are susceptible to leaf spot diseases in wet summers. Blackgum is resistant to damage by deer.

Six superior blackgum cultivars:
Red Rage® (‘Hayman Red’) – reportedly leaf spot resistant along with great fall color.

‘Wildfire’– new spring leaves emerge with reddish tint, turn glossy green in summer, and an outstanding red fall color.

Firestarter™ – ascending narrow branching and strong central leader; dark green summer leaves turn intense red in fall.

Green Gable™ – strong pyramidal habit, glossy green leaves and great red fall color.

‘Sheri’s Cloud’ – medium green leaves edged with a creamy-white margins; bi-color fall color.

‘Zydeco Twist’– slightly contorted, zigzag branches.

‘Autumn Cascades’– unusual weeping branching habit and outstanding fall color.

Blackgum (Tupelo) – Fall Leaf Color And Fruit Attract Birds And Other Wildlife

13 Native Trees For Fall Color

Posted by Hugh on September 11th, 2020

1. Sweet gum (Liquidambar styraciflua) – large 60-80 feet tall tree whose fall color is a brilliant mixture of yellows, oranges, purples and reds. Zones (5b)6-9).

2. Black gum, tupelo (Nyssa sylvatica) – large 50-50 feet tall tree produces spectacular scarlet fall color. Lots of good cultivars including Green Gable®, ‘Wildfire’ and Red Rage® (Zones 3-9).

3. Red maple (Acer rubrum) – large 40 -60 feet tall shade maple known for fast growth rate. ‘October Glory’, ‘Red Sunset’, and others have superior red fall color. (Zones 3-9).

4. Sugar maple (Acer saccharum) – major contributor of fall color in the eastern and Midwest U.S. and Canada (Zones 3-7).

5. Red oak (Quercus rubra) – up to Up to 75 feet shade and forest tree Leaves turn crimson, orange, and russet in fall. (Zones 3-7).

6. Quaking aspen (Populus tremuloides) – 30-50 foot tree that from central U.S., particularly the Rocky Mountain states; its circular-shaped glossy green leaves shimmer in the slightest breeze and turn gold to orange. (Zones 1-6).

7. Flowering dogwood (Cornus florida) – this eastern U.S. native dogwood displays vivid fall colors; leaves turn red purple; birds are attracted by the glossy red berries. (Zones 6-9).

8. Vine maple (Acer circinatum) – small 25-35 feet tall maple native to the Pacific Northwest and British Columbia. In fall the leaves turn orange scarlet or yellow. (Zones 6-9).

9. Sassafras (Sassafras albidum) – lobed or mitten-shaped leaves; 35-50 feet tall displays fall color (purple, red, orange and yellow), highly variable from one region to another. (Zones 4-9)

10. Mockernut hickory (Carya tomentosa) – large tap-rooted 50-60 feet tall woodland tree in the eastern and Midwest U.S. exhibits above average golden yellow-brown fall color; not commonly sold at nurseries (Zones 4-9).

11. Sourwood (Oxydendrum arboreum) – 25-50 feet tree that consistently excellent crimson red fall color; creamy 4-8 inch long finger-like white flower panicles remain through fall. (Zones 5-9)

12. American persimmon (Diospyros virginiana) – large 50- 60 feet tall tree with yellow green fall leaf color in northern U.S. and yellow to reddish purple in the South (Zones 4-9).

13. Franklin tree (Franklinia alatamaha) – native to southeast Georgia, this small 12-20 feet tall tree produces white camellia-like flowers in late summer; variable orange-red fall foliage. (Zones 6-8).

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).