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

‘Nellie R. Stevens’ Holly Sets A High Standard

Posted by Hugh on November 20th, 2011

'Nellie R. Stevens' holly

‘Nellie R. Stevens’ (‘NRS’) is a tall growing red fruited female holly, a cross between the English (Ilex aquifolium) and Chinese (I. cornuta) hollies. ‘NRS’ comes highly recommended for Southern Appalachian landscapes (USDA zones 6 and 7).

Hollies are dioecious, requiring both male and female parents for fruit production. ‘NRS’ holly produces small numbers of seedless parthenocarpic fruits without a male pollinator being present. More fruits are produced naturally when ‘NRS’ is properly mated to the male cultivar such as ‘Edward J. Stevens’ and another I. cornuta holly. One male holly adequately pollinates 8-10 female plants located within several hundred feet. Red fruits are not as persistent as ‘Emily Bruner’, another holly favorite.

Hollies are spaced apart according to their intended use in a planting. ‘NRS’ is an outstanding “stand alone” specimen or you can hedge several together to form a tall privacy screen. Annual growth rate is moderate, about half that of Leyland cypress (x Cupressocyparis leylandii). ‘NRS’ holly is a lot more dependable and long-lived.

‘NRS’ is a strong grower at 25-30 feet tall and 15-18 feet width over 30 years. If planted as a privacy screen, plant on a minimum of 12 foot centers (between plants).

Hollies prefer an open sunny location and moderately acidic, well-drained soil. Established hollies are good foragers for nutrients and benefit from annual feeding with an acidic based fertilizer such as Hollytone®, Miracid® or Miracle Gro®.

European Beech Prefers Cool Climes

Posted by Hugh on November 18th, 2011

Fagus sylvatica 'Pendula' in a Boston, MA Park

European Beech (Fagus sylvatica) is native to the cool temperate regions of Europe. In the U.S. it is more at home in the Northeast, Upper Midwest, and Northwest regions (USDA Hardiness Zones 4 to 7) where summers are cool. European beech grows in full sun and moist, well-drained soils, ranging from mildly acidic to low basic. The tree suffers in the Southeastern U.S. heat and waterlogged clay soils.

Because of its large size and slow growth rate, European beech needs a few years to adapt to its planting site. Utilize this large specimen shade tree in public parks, golf courses, commercial properties and estates. European Beech grows 50 to 60 feet high and 40 feet wide with a dense, upright, oval form. It grows 10-20 % smaller than American beech (F. grandifolia) and its trunk bark is a darker gray.

European beech is a long lived. Trees planted by Thomas Jefferson at Monticello in 1807 survived almost 150 years. Very little vegetation grows under its dense tree canopy which carpets and shades the ground beneath with leaf mulch. Livestock, wildlife, and humans snack on beechnuts.

Leaves are dark green in summer and turn a stunning russet brown in the autumn. Two to three year old established trees can tolerate short 1-2 week long drought spells. Purple leaved cultivars tend to be less summer heat tolerant.

European beech responds well to heavy pruning and several together are grown as a tall hedge in Europe. Foliage and twigs are not tolerant of salt, including de-icing salts used on roadways.

European beech lists over 30 cultivars which includes these popular six:

‘Asplenifolia’- fern-like or cutleaf foliage.
‘Atropunicea’ (Copper beech) – spring/early summer purple leaves.
‘Dawyck’, aka ‘Fastigiata’ – narrow, upright branching habit.
‘Pendula’- weeping habit.
‘Riversii’- dark purple leaves.
‘Roseomarginata’ (Tricolor beech) – with green and white leaves with pink margins.

For Lovers and Tree Huggers – American Beech

Posted by Hugh on November 15th, 2011

American Beech: Dark Tan Foliage/Gray Bark in Late Autumn

Mighty as an oak pretty much describes American beech (Fagus grandifolia) as well. Enjoy all four seasons of American beech: spring/summer dark green leaves, dark tan colored fall foliage, long pointed winter buds, and bluish gray bark. It is a large 50-70 foot woodland tree and tolerates incredible amounts of shade.

Slow growing beeches are long-lived and best planted on large ground acreages such as golf courses, public parks, and corporate centers where future generations can enjoy them. Plant them in a well-drained, slightly acidic, loamy soil. Contrary to what’s written in many books, American beeches transplant easily either as container-grown or balled and burlapped (b&b) nursery stock.

Constructing a home inside a woodlands is usually destructive to the beech and oak (Quercus spp.) occupants. Beech roots are sensitive to being “stepped on” by heavy construction equipment or covered up with soil and debris. Also, don’t plan to grow a lawn because beech is shallow rooted and casts a dense foliage canopy. Its serrated edged leaves are 3-5 inches long and 1-2 inches wide, presenting an overall fine leaf textured appearance.

American beech is monoclonal while European beech (F. sylvatica) offers several cultivars. Beechnuts are an important fall/winter food source (called “mast”) for many wildlife species. In recent years a potentially serious beech bark disease complex has destroyed hundreds of acres of American beech across the U.S. Long summer dry periods have contributed to American beech losses.

Its gray colored bark has been a favorite of lovers who proclaim their everlasting love for one another by etching their initials into beech trunks. It would be healthier for beech if they went to courting with candy or flowers.

‘Morgan’ Oriental Arborvitae

Posted by Hugh on November 12th, 2011

'Morgan' oriental arborvitae in Knoxville, TN Garden

Among dwarf conifer collectors, ‘Morgan’ Oriental arborvitae (Platycladus orientalis) has become one of the most sought out evergreens over the past decade. Its oval form and seasonal coloration makes Morgan a standout. It performs well in part sun, but its chartreuse-yellow foliage appears more vibrant in direct sunlight. Its dense foliage grows in vertical layers.

Andy Pulte at the University of Tennessee, another conifer addict like myself, classifies Morgan arborvitae as a “chameleon”. By late fall a purplish tinge has bled into the foliage and has turned to coppery orange by late winter. Early spring warm temperatures will force new growth and a return to the chartreuse-yellow coloration.

Morgan has a long garden life and a slow 2-4 inch growth rate per annum. Plant in a well drained compost rich soil and space a minimum of 3-5 feet away from other shrubs and perennials.

Irrigate and fertilize Morgan during the first two years to insure its longevity. Acid-based water soluble fertilizers such as Miracle Gro™ or Miracid™, or slow- release Hollytone® are good products. Read and follow package directions.

Morgan arborvitae adds four-seasons interest and is a perfect fit into any small garden or container (zone 6 and further south). Once considered as a collectors’ only plant, Morgan is finding its way into mainstream nursery commerce. Morgan arborvitae adds four-season interest and is a perfect fit into any small garden.

Reference Conifer Gardens in the Southeastern U.S.

Posted by Hugh on November 7th, 2011

Conifers in “Trees for Tomorrow” Bed at ETSU Arboretum in Johnson City, TN

The American Conifer Society (ACS) supports public conifer gardens around the U.S. Reference Gardens offer plant professionals and home gardeners an opportunity to evaluate conifers growing in a landscape or garden setting within their geographic region. You can compare the unique foliage colors, shapes, and growth habits which conifers offer. You can select conifer(s) which work as privacy screenings, medium shrubs, or low ground covers.

Here is the current listing of 12 public conifer gardens in the U.S. Southeastern Region published by ACS:

State Botanical Garden – Athens, GA

The State Botanical Garden of Georgia is a public educational facility, encompassing more than 300 acres, and operated under the auspices of the University of Georgia. Several hundred conifers are planted in the gardens.

Atlanta Botanical Garden – Atlanta, GA

The Rare and Unusual Southern Conifer Garden at the Atlanta Botanical Garden was originally planted in 1994 located immediately in front of the conservatory. Two additional beds were added in 1998.

University of Tennessee Gardens – Knoxville, TN

Since 2005, the UT Gardens conifer collection has grown to over 365 specimens, representing 19 genera.

East Tennessee State University Arboretum – Johnson City, TN

The ETSU Arboretum was established in 2001 and its conifer collection currently includes approximately 130 species and cultivars in 25 genera.

South Carolina Botanical Garden – Clemson, SC

The conifer collection is primarily located in the Schoenike Arboretum and includes over 81 species within 20 genera.

University of Tennessee – Jackson, TN

The University of Tennessee West Tennessee Research and Education Center in Jackson The UT Gardens in Jackson began in 1989. The conifer collection, began in 2006, holds over one hundred specimens.

State Arboretum of Virginia – Boyce, VA

The conifer collection contains 1,635 specimens in 243 taxa. The largest single plant collection within the gymnosperms is the ginkgo with 324 specimens.

JC Raulston Arboretum – Raleigh, NC

The JC Raulston Arboretum was started in 1976 and the conifer collection has expanded to include 870 conifers comprised of 499 different taxa in 38 different genera.

Smith-Gilbert Gardens – Kennesaw, GA

Smith-Gilbert Gardens is approximately 25 miles from downtown Atlanta. The gardens contain over 230 conifers representing 26 genera.

Al Gardner Memorial Conifer Garden – Goochland, VA

This new garden, on the campus of J. Sargeant Reynolds Community College, Western Campus (between Richmond and Charlottesville), has 37 conifer specimens representing 11 different genera.

Lewis Ginter Botanical Garden – Richmond, VA

Visitors can encounter an attractive blend of diverse and fascinating dwarf and full sized conifers.

Lockerly Arboretum – Milledgeville, GA

Lockerly Arboretum was founded in 1966 and their extensive conifer collection in the Pinetum area recently added over fifty new varieties.

————————————————————————————————–Additional U.S. Conifer Reference Gardens are found in the Northeast, Central and West Regions. Check out the American Conifer website: www.conifersociety.org.

Visit an ACS Reference Garden near you.

Making A Case for Mugo Pine

Posted by Hugh on November 4th, 2011

'Mops' Mugo Pine at New Hope Garden Center, Blountville, TN

Mugo pine (Pinus mugo) is a slow growing needle evergreen shrub of variable heights ranging from 5 feet to 20 feet and more. Mature height depends on the cultivar planted and environmental conditions on site. Mugo pine is native over many hundreds of miles of alpine climes across Europe. It is winter hardy in USDA zones 3-7, but its heat tolerance in southern parts of zone7 is sub-par.

This shrub pine grows best in full sun, but can tolerate light shade. The key to successfully growing mugo is a moist well-drained loamy soil. Planting in wide shallow holes on raised bed(s) is highly recommended. Mugo has a disease prone shallow rootsystem. Add mulch to keep roots moist and cool. Two-year established mugo pines exhibit good summer drought tolerance.

The 1-2 inch long dark gray/blue stiff needles are borne in bundles of two. The densely packed needles exhibit a long 5-6 year retention life before succumbing to natural needle drop in early fall.

There is great variability among mugo pines in terms of growth rate, size and shape. The popular variety ‘pumilio’ often grows beyond its stated size and form. ‘Mops’ is the preferred dwarf cultivar, growing 3-5 feet tall and 5-6 feet wide. ‘Mops’ may be utilized as a groundcover, included in a low foundation planting, or set in a rock garden. Selected hand pruning of young developing shoots (“candles”) in late spring may dwarf ‘Mops’ or other cultivars even further.

Mugo pine is susceptible to root rot diseases in poorly drained soils. Pine sawflies and tip moths are key insect pests. Quick monitoring and spraying with acephate (Orthene®), cyfluthrin (Bayer Advanced Garden Multi-Insect Killer®), or carbaryl (Sevin®) insecticides will keep these serious pests in check.

‘Snow Flurry’ Zone 6 Hardy Camellia

Posted by Hugh on October 31st, 2011

Fall Blooming 'Snow Flurry' Camellia

‘Snow Flurry’ camellia is a broadleaf evergreen shrub with good plant vigor. It was one of the first zone 6 cold hardy camellias hybridized by Dr. William Ackerman and released by the U.S. National Arboretum in 1986.

Snow Flurry grows into a 4 feet tall by 6 feet wide shrub over a 10 year span. Branching is mostly upright with branch tips bending downward, mostly from weight of the numerous flowers produced. The medium-sized (3 ½ inch) white flowers open in early autumn. Flower shapes may vary from peony to anemone types on the same shrub.

Camellia culture is similar to rhododendrons. Camellias prefer partial sunlight (6-hours minimum) for optimal flowering. Garden soil should be moist, well-drained, and slightly acidic. The planting site should be generously amended with peat moss and /or compost. Plant shrub(s) shallow in a wide planting hole, slightly above soil grade, and spread 2-3 inches of an organic mulch around each shrub. The planting site should be partially sheltered from winter’s desiccating winds and direct afternoon sunlight year-round.

Camellias require little to moderate pruning annually, depending on the cultivars grown. Pruning is best performed in mid to late April before new vegetative growth begins. Newly planted shrubs are drought susceptible, but two-year established camellias tolerate summer dry spells well. Their lustrous green foliage is tolerant of coastal sea salt spray.

Fertilize with acidic- based plant foods such as Hollytone™, Miracle-Gro™ and Miracid™. Follow package directions and don’t fertilize camellias after August 15^th.

Currently, disease and insect problems are almost non-existent in zone 6 areas of the Southern Appalachian region (USDA zones 6 and 7).

Irrigate Evergreens This Winter

Posted by Hugh on October 28th, 2011

Spruce Container at Biltmore Estate, Asheville, NC

Fall slowdown in the garden brings many of us back indoors to prepare for the winter holidays ahead. A number of serious canker diseases attack evergreens in the fall and winter if soil moisture is not plentiful. These diseases include botryosphaeria, cytospora, phomopsis, and seiridium cankers. Each organism is capable of causing branch dieback or death to the entire shrub or tree.

Evergreens such as laurels, rhododendrons, spruces, Leyland cypress, upright junipers, and arborvitae are the most susceptible. In late fall, around Thanksgiving, deep watering of evergreens in the ground is generally good insurance against disease. Weekly watering entails supplying 1 inch of natural precipitation (rain or snowfall equivalent) and/or irrigation.

A gardener should be aware of the natural environment. In particular, needle conifers in containers may be in most jeopardy of the winter weather ahead. Wintry winds may desiccate needles rapidly. An evergreen’s umbrella-like branch canopy reduces the amount of rain and snowfall that reaches the root mass in the container.

Containerized evergreens in the Southern Appalachian region (USDA zones 6 and 7) should be watered every 8-10 days over the winter months. Container media may freeze solid for a few days during winter cold snaps, but the media thaws out and the plant re-hydrates. A fully hydrated plant is better able to cope in frozen media than one in drycontainer media.

Evergreens should be transplanted into larger containers and fresh media every 2 to 3 years.

Credit: Information supplied by Dr. Alan S. Windham, Extension Plant Pathologist, University of Tennessee, Plant Diagnostic Lab, Nashville

Natural Evergreen Needle Drop in Autumn

Posted by Hugh on October 25th, 2011

Natural Needle Fall in Pine in October

Some needle loss on evergreens in the fall is natural. As night time temperatures cool, needles in the interior of many evergreen trees or shrubs regularly turn brown (or golden yellow) and drop off. Needle loss is most obvious on pines (Pinus spp.) and arborvitae (Thuja spp.) in the Southern Appalachian region (USDA zones 6 and 7).

The numbers of needles shed may vary from one year to the next. Unusually high needle losses may be a reaction to high summer heat and extended dry periods within the geographical area where you live.

Loss of two year and older needles is natural. Loss of current season and last year’s needles is painfully not a good thing and may be caused by a disease or insect pest. Roots of evergreens may contract a root disease such as pythium and phytophthora fungi. Often, a root disease may be fatal or the pesticide treatment(s) very costly.

Environmental and transplanting stresses may be the cause. Winter desiccation and de-icing salts can turn evergreens brown. Needle losses are usually higher on newly planted evergreens.

Weekly deep watering in the fall and late winter fertilizing of evergreens helps relieve transplant stress. Transplant shock (heavy needle loss) should not re-occur the following fall.

Note: More on fall-winter care of evergreens coming soon.

Alaska Cedar Is Awesome Weeping Evergreen

Posted by Hugh on October 21st, 2011

Alaska Cedar at Kingwood Center, Mansfield, Ohio

Over the past decade, gardeners have been planting different evergreen trees in their Southern Appalachian landscapes (USDA zones 6 and 7). One of the newbies is Alaska cedar (Chamaecyparis nootkatensis), a wonderful medium-sized evergreen tree from the west coast of North America.

Alaska cedar matures into a graceful pyramidal tree form. Long pendulous flattened sprays of bluish green needles drape from the mostly horizontal branches. Needles turn grayish green in winter. Tall (40-50 feet) and narrow (15-25 feet) in stature, Alaska cedar is long-lived and a slow grower until established. It grows best in full to partial sunlight (6 hours minimum) in a compost rich, well-drained soil. A newly planted tree benefits from weekly irrigation over a hot, dry summer until fully established in three years.

Dense evergreen foliage conceals the reddish brown shredding bark within. Bark on an older trunk and branches appears ragged and gray colored. Flowers and ½- inch diameter seed cones are insignificant and require little cleanup. Alaska cedar has no serious disease or pest problems.

There are over 15 selections of Alaska cedar in nursery commerce. ‘Pendula’ (more weeping form), ‘Green Arrow’ (narrow) and ‘Van den Akker’(very narrow) are popular cultivars. Plant any one of these fabulous Alaska cedar cultivars nearby a deck or patio where it likely will become a major focal point in your landscape.

Alaska cedar has recently been reclassified as Cupressus nootkatensis.