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

Deer Don’t Feed On Plum Yews

Posted by Hugh on December 10th, 2012

Cephalotaxus harringtonia 'Duke Gardens'

Plum yews (Cephalotaxus harringtonia) are evergreen needle conifers which flourish in the heat and humidity of the Southeastern U.S. (USDA hardiness zones 6-9). Likely, the groundcover forms are hardier to zone 5-b if protected by snow cover or surrounding vegetation from dry winter winds.

Plum yews are native to China, Korea and Japan. Many people confuse them with Japanese yews (Taxus spp.) which grow poorly in southern clay soils and are highly susceptible to deer feeding. Plum yews are highly deer resistant*.

Plum yews start out growing slowly, but catch up once established in 2 years or less. Lustrous dark green evergreen needles vary in length from ¾ to almost 2 inches. Foliage retains its lush green color through the winter months.

Plum yews substitute for Japanese yews (Taxus spp.)in the south. Available cultivars vary in plant height and growth form. Plum yews cope with either light shade or full sun. They prefer a moist well drained soil, but established plants exhibit good drought tolerance.

There are 3 distinct growth forms of plum yew:
‘Fastigiata’ is a columnar form that grows 10 feet tall and 6-8 feet wide in 15-20 years.
‘Prostrata’ and ‘Drupacea’ grow 2 ft tall and 20 plus feet wide. Clip off aberrant shoots that spring up to maintain a uniform groundcover appearance.
‘Duke Gardens‘) has a semi-upright, spreading shrub appearance similar to spreading forms of Japanese yews (Taxus x media) or (T. cuspidata). It was found at Sarah P. Duke Gardens in Durham, N.C. as a chimera (mutation) on ’Fastigiata‘.

* Deer resistance is based on “normal” population numbers. Deer will feed on most plants if their populations are exceptional high or when natural food resources become depleted.

‘Beni kawa’ Japanese Maple for Winter Bark Color

Posted by Hugh on December 10th, 2012

10 year old Beni kawa Japanese maple

Beni kawa Japanese maple (Acer palmatum ‘Beni kawa’) is a smaller version of the popular coral bark maple ‘Sango kaku’. It was introduced by Greer Gardens Nursery in Oregon in 1987. ‘Beni kawa’ matures to 12-15 feet tall and 8-10 feet wide, compared to 20-25 feet tall for ‘Sango kaku’. Both cultivars form a vase-shaped branched small tree or large shrub. The pale green bark on the trunk and stems turns coral red in winter.

The 5-7 pointed palmate leaves emerge soft green in spring, and fall foliage color ranges from yellow to orange. The leaves tend to emerge early in spring and may be subject to injury from late spring frosts. The small reddish flowers in spring are attractive up close, and are mostly inconspicuous from a distance.

The foliage may burn in direct summer sun in USDA zone 7 and 8, preferring some afternoon shade protection. Japanese maples grow in a compost rich, well- drained, and moderately acidic soil. Irrigation and mulching are desirable during summer dry spells and protect roots from dry winter winds. Pruning, if needed, is best performed during the spring and summer months to avoid significant sap bleeding from the pruning cuts.

There are no serious insect or disease problems. Beni kawa appears to be slightly more cold tolerant than Sango kaku. Beni kawa is sometimes mistakenly spelled “Beni gawa”.

Franky Boy Arborvitae

Posted by Hugh on December 5th, 2012

'Franky Boy' arborvitae in Late November at UT Gardens, Knoxville, TN

Franky Boy oriental arborvitae (Platycladus orientalis ‘Franky Boy’ [syn Thuja orientalis]) is a dwarf evergreen conifer currently in hot demand among collectors. What immediately catches your eye is its thread-like foliage which changes color from one season to the next. Its evergreen foliage adds a fine textured look to the landscape.

The new spring growth is fountain-like, e.g. it bubbles out from a central growing point and weeps downward. In the spring and summer threaded foliage is chartreuse colored. In the fall and winter it morphs again, first with a bronze tint or later to copper orange. By early spring the light green color has returned.

Over a 10 year span, expect Franky Boy to grow 4 to 5 feet tall and 3 to 3 ½ feet wide. Oriental arborvitae is safely winter hardy to USDA hardiness zone 6 and may be borderline in zone 5-b if protected from wintry winds, heavy snow, and ice storms. Pruning, while rarely necessary, can create a tight, more compact shrub.

Franky Boy thrives in full to partial sunlight. A moist, compost rich, well-drained soil is ideal. It becomes heat and drought tolerant after a 2-year establishment period. Plant Franky Boy in a large patio/deck sized container or utilize it as an accent or textural shrub as a portion of the foundation planting.

Blossom End Rot Affecting Your Vegetables?

Posted by Hugh on December 1st, 2012

Blossom End Rot on Tomato (photo credit- Dr. Steven Bost, Univ. of Tennessee Plant Pathologist)

The bottom side of your tomato fruits appears to be rotting? The problem is not a disease, but a calcium disorder called “blossom end rot of tomatoes”. This nutritional malady also affects squash, pepper, eggplant, melon, and cucumber.

There are 3 causes for calcium deficiency: 1.) a deficiency of available calcium in your garden soil, 2.) inadequate soil moisture, or 3.) over-feeding plants with nitrogen fertilizer. One, two, or all three causes may in play at the same time.

Watering during periods of extreme drought will feed more soil calcium to the plant. Irrigate to make up for natural rainfall deficits. up to 1 ½ inches per week. Mulching around vegetable plants with grass clippings, straw, or wood chips also helps. Be certain that lawn clippings have not been sprayed over the past month with herbicides which control dandelions and other broadleaf weeds.

Lime is a good source of calcium, but it takes several weeks for quick forms of lime to breakdown and become easily absorbed by roots. Dolomitic (gray) and hydrated lime may take 3-4 months to activate in a soil and are best applied over the winter months. Test your garden soil in autumn to determine when and how much lime to add. Use the correct amount as lime will raise the soil pH, making it less acidic.

High nitrogen levels may promote rapid vegetative growth, but the plants don’t absorb enough calcium to compensate, resulting in localized calcium deficiency in the fruit (or vegetable).

Finally, plant roots amy become injured from flooded soil or mechanical injury from tillage equipment such as hoes and rototillers. Root loss from poor aeration means the plant is not taking up enough water and nutrients.

Are You Growing A Thanksgiving or Christmas Cactus?

Posted by Hugh on November 27th, 2012

Thanksgiving cactus for sale in Garden Center

If your “Christmas cactus” is blooming on Thanksgiving Day, it is likely not a true Christmas cactus (Schlumbergera x buckleyi) which flowers a month or more later. Thanksgiving cactus (S. truncata) is frequently sold as “Christmas cactus”. Holiday shoppers often decorate with what’s in the store after Thanksgiving and the plants are frequently mislabeled.

Christmas cacti feature smooth round edges, while Thanksgiving cacti have pointed or jagged segmented edges. Both flowering cacti come in similar floral colors and require the same care. Both holiday cacti live for many years. In fact, you may inherit grandma’s Christmas cactus.

Indoor room temperature and daylength (photoperiod) determine flowering time. Both cacti require cool temperatures (50 to 55°F) to initiate flower buds. Locate the potted cactus near a cool window. The container can be moved outdoors on cool autumn days and brought inside when temps dip below 40°F. Holiday cacti are also “short day” plants, meaning they initiate flower buds in response to 13 or more hours of non-interrupted darkness over 6 weeks.

If you can’t precondition your plant, the side facing the window likely will develop some flower buds (unless a bright street light is nearby). The side of the plant facing a light source inside the room may not bloom because its “nighttime” phase has been interrupted by an evening light source inside the room.

Repot holiday cacti annually, preferably in late winter into new potting media. Feed the plant with house plant food such as Miracle-Gro® or Schultz® fertilizers. Use 1/2 the recommended rate and feed twice monthly from March thru December. Plant(s) can be grown outdoors in the spring and summer months under a shade tree.

‘Sweet Tea’ Heucherella Offers Year-round Foliage Color Splash

Posted by Hugh on November 24th, 2012

Heucherella 'Sweet Tea' (photo by David Sanford, PSU Horticulturist, Reading PA)

Heucherella or foamy bells is a hybrid derived from crossing U.S. native foamflower, (Tiarella spp.), with coral bell (Heuchera villosa), another U.S. native. Terra Nova Nurseries, a wholesale grower in Oregon, has introduced several of these hybrids. Heucherellas bring out the best traits of both parents. Their small creamy white, bell-shaped flowers open in late spring on sturdy stems which stand tall above the colorful foliage. Blooms attract numerous butterflies.

‘Sweet Tea’ foamy bells (Heucherella x ‘Sweet Tea’) is a true garden performer. Large 4-inch wide palmate leaves become an orange colored tapestry that changes from month to month. New spring leaves are bright orange. Some gardeners may opt to clip off flower stems to emphasize the rustic orange foliage colors. Leaves darken in the summer, and become a blend of orange and coppery shades in the autumn. Winter foliage is semi-evergreen in the Southern Appalachian region (USDA hardiness zones 6 and 7) and is fully evergreen further south.

Heucherella ask for very little maintenance. Sweet Tea grows 20 inches tall and 28 inches wide. It is best planted in organic rich, well-drained soil and in a partially shaded area. Irrigate a new planting over the first year and mulch around plants for additional moisture conservation. Sweet Tea tolerates summer’s heat and dry periods because of its H. villosa bloodline (USDA Zones 4–9).

‘Morgan’ Oriental Arborvitae

Posted by Hugh on November 20th, 2012

'Morgan' Oriental Arborvitae (Platycladus orientalis)

When dwarf conifer hobbiests visit one another’s gardens, they discover new plants, some which later show up in their own landscape. Morgan oriental arborvitae (Platycladus orientalis ‘Morgan’) has become very popular among collectors living in the southeast and mid-Atlantic regions.

Morgan arb is a fairly slow-growing, typically 5 inches or less per year. It provides year-round interest, as foliage color changes with the seasons. The sprays of lovely chartreuse foliage are layered vertically, offering up a different textural look. The summery lime green, scale-like foliage takes on a purplish to bronze tint in the frigid winter; the more typical chartreuse color returns as springtime nears.

Morgan arb is safely winter hardy to USDA hardiness zone 6 and rated as borderline in zone 5 where it requires protection from drying cold winter winds. The vertical pads may split apart from heavy snow and ice and are best tied up with wire or soft twine.

Morgan arb thrives in full sun to partial shade. It becomes heat and drought tolerant after a 2-year establishment period. It is a good evergreen and textural choice planted in a large patio/deck sized container or part of a foundation planting.

Grow Morgan arb in a rich well-drained garden soil or potting media. Feed with a slow release fertilizer specific for evergreens such as Hollytone™ or Schultz™ Evergreen products applied in late winter before spring growth begins.

Promising New American Chestnuts Arriving

Posted by Hugh on November 17th, 2012

Chinese Chestnut on East TN State University Campus, Johnson City, TN

Chestnut blight (Diaporthe parasitica Murrill) was first discovered in the Bronx Zoo in 1904. By 1911 the headline in The New York Times read – “All Chestnut Trees Here Are Doomed”. Over the next half century, the pandemic eliminated four billion trees. Today, the airborne bark fungus still persists in the soil and on diseased trees.

In the late 19th century chestnut trees, with their furrowed bark, long toothed leaves and spine-covered fruit, were as common as oaks and walnuts. Single straight trunked trees rose 90 to 100 feet tall and harvested for high-quality timber. Chestnuts, the raw or roasted kind, were traditional winter morsels for both squirrels and humans alike.

Beginning in 1989, the Chestnut Foundation, at its research farm in Meadowview, VA, began a new breeding project. Chinese chestnut (Castanea mollissima) is very blight-resistant. Plant breeders “backcrossed” the Chinese-American hybrids with American chestnut (C. dentata) with the goal of adding more “American blood” to each generation going forward and, at the same time, retain blight resistance. Current hybrids are genetically 94 percent American chestnut.

The new blight-resistant American chestnuts represent 22 years and six generations of breeding. Three years ago, the Forest Service began planting the foundation’s “Restoration Chestnuts”, which are 15/16ths American, in U.S. National Forests in Tennessee, North Carolina and Virginia. It may take 60 or 80 years to determine whether one or more blight resistant cultivars have been found.

Credits: this is short summary of the information available from American Chestnut Foundation on-line.

Autumn Best Planting Time For Spring-blooming Dogwoods

Posted by Hugh on November 13th, 2012

Cornus florida 'Appalachian Joy' (photo submitted by Dr. Alan Windham, UT Plant Pathologist)

“Autumn is the season to plant dogwoods”, according to the University of Tennessee Dogwood Research Team. Newly planted dogwoods (Cornus spp.) can establish their roots in the still warm soil and be ready to handle next spring and summer’s heat and dry spells.

Over the past 20 years the UT Dogwood Team has released six highly disease resistant dogwood cultivars of flowering dogwood (C. florida) under the ‘Appalachian’ series logo. So far, white flowering ‘Appalachian Spring’ is the only dogwood cultivar resistant to the dreaded anthracnose (Discula) disease. ‘Appalachian Mist’, ‘Appalachian Snow’, and pink-tinged ‘Appalachian Blush’ are white-bracted cultivars that are highly resistant to powdery mildew.

‘Appalachian Joy’ is the newest introduction in the powdery mildew resistant line. Its flowers develop 1-2 extra bracts to present a showier floral display.

Flowering dogwood (C. florida) defines the adage – “the right plant in the right environment”. It is a native understory tree and should be planted in partial sunlight. Full morning sunlight is preferred in the Southern Appalachian region (USDA hardiness zones 6 and 7). While a slightly acidic moist well drained soil is ideal, flowering dogwood develops above average summer drought and heat tolerance after two years on site.

Compare C. florida to Chinese dogwood (C. kousa), the latter requires deep watering 2-3 times over the summer. Kousa’s pointed white bracts appear 2-3 weeks after flowering dogwood has finished. The UT dogwood team is currently testing better anthracnose resistant Chinese dogwoods, including a space-saving narrow columnar growing form.

Sugar Maple Is A Four Star Autumn Attraction

Posted by Hugh on November 9th, 2012

Sugar maple autumn color

Spring flowering

Sugar maple (Acer saccharum) is a native deciduous tree often planted as a large shade or street tree. It commonly grows 60 to 75 feet (and taller) with a dense rounded foliage canopy. Native to central and eastern North America regions, sugar maple grows best in fertile, mildly acidic, moist well-drained soils and in full sun to part shade.

The 5-lobed deep green leaves of summer takes on yellow, orange and red shades in the autumn. Clusters of yellowish-green flowers appear in mid-spring a week before the leaves emerge. Flowers ripen into clustered pairs of double-winged samaras (or “helicopters”) in late summer. In the winter tree trunks may be tapped for maple syrup (“saccharum” means sugar).

Disease and pest problems are less when properly sited and maintained. Do not plant in dry compacted sites such as in downtown parking lots or as street trees. Poor locations bring on numerous serious diseases and insects, including verticillium and fusarium wilts, leaf spots, cankers, wood borers and scale. Its shallow roots raise up urban sidewalks.There are more than 25 sugar maple cultivars, and here are three exceptional ones.

‘Green Mountain’ has broadly pyramidal tree form. The foliage may struggle in summer heat and dry periods, causing leaf edges to brown (scorch). However, its thick deep green foliage is resistant to leaf hoppers and scorch, making it an ok choice as a street tree.

‘Legacy’ sugar is a more heat and drought resistant, making it a good pick for the southeastern U.S. The tree canopy is densely branched and has glossy thick green leaves. The leaves turn yellow to orange in autumn.

‘Green Column’ (A. saccharum subsp. Nigrum), aka black maple, exhibits better than average heat and drought resistances. Summer foliage is dark green and is thick and leathery to the touch. It develops a yellow fall color that’s two weeks later than other sugar maples.