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

European vs Asian Pears

Posted by Hugh on December 4th, 2011

Luscious European Pears

Growing pears in the Southeastern U.S. is both challenging and rewarding. Both the European (Pyrus communis) and Asian (P. pyrifera) pears are susceptible to fireblight (Erwinia amylovora), a bacterial disease with no satisfactory cure. Two popular European pear varieties, ‘Bartlett’ and ‘Bosc’, are highly susceptible to fireblight. Varieties found to be fire blight resistant are: ‘Warren’, ‘Aires’, and ‘Moonglow’. ‘Shinto’ is an Asian pear variety with crispy russet brown fruits and possesses above average fireblight resistance.

European pears are unique in that the fruits do not ripen on the tree. Fruits must be harvested on a scheduled date for each variety and ripened indoors. The unripened pears are stored in a closed plastic or paper bag (sack) for 7-10 days at room temperature (60-70 °F). Fruits are then refrigerated to slow down ripening.

Asian pears ripen on the tree like apples, and are ready to eat when harvested. Asian pears are picked from late August to early October, depending on the variety grown.

European pear varieties will not pollinate Asian pears. Asian pears tend to bloom several days later than European varieties. Both European and Asian pears also require cross-pollination of two different varieties.

Both European and Asian pears are notorious for “biennial bearing”. A tree may overproduce one year, and yield a small crop the next (the ‘off” year). Biennial bearing in the “on” year often results in limb breakage and smaller fruits. To prevent or break the biennial bearing cycle, remove excess fruits by hand within 30 days after full bloom in the “on” year. As a rule, one pear fruit is supported by 30-40 leaves.

Dwarfing Rootstocks for Apple Trees

Posted by Hugh on December 3rd, 2011

Yummy Apples

No more climbing ladders to pick apples. Less waiting for first harvest for newly planted tree. These are some of the reasons for planting dwarf apple trees. Over the past 100 years numerous dwarf rootstocks have been introduced.

In addition to the degree of dwarfing, some rootstocks are more disease and insect resistant. The original East Malling Research Station in England (“EM rootstocks”) reduced tree size and led to earlier first harvests. However, EM rootstocks are not resistant to wooly apple aphid in the southeastern U.S.

A second series from England, designated Malling Merton (MM), are wooly aphid resistant. Recent rootstock introductions are the Geneva series (G), which are resistant to fire blight (Erwinia amylovora) and collar rot (Phytophthora spp.) diseases.

Popular Rootstocks Size control

EMIX*, Bud 9* 70% reduction in size

M26*, G16A, G11A* 60% reduction in size

EMVII*, G30A* 50% reduction in size

MM106 25% reduction in size

MM111 20% reduction in size

Disease and insect resistances of the various rootstocks vary. Check with your local Extension office to determine which pests are prevalent in your area. Apple trees on dwarf rootstocks should not be permitted to crop until the third year after planting. Those rootstocks indicated with * tend to be shallow rooted and require staking for tree support.

Growing Elderberries in the Garden

Posted by Hugh on December 2nd, 2011

Elderberry crop in late August

Elderberry (Sambucus canadensis) is native to eastern North America, commonly found growing in open fields, thickets, fence rows, and along roadsides. Elderberry has pinnate leaves with toothed leaflets. Large flat clusters of small white flowers are evident by early summer, followed by large clusters of round purple-black fruit in late summer and fall.

The fruits are magnets for attracting all kinds of winged and four legged wildlife to your garden. They are tasty, high in vitamin C, and should be boiled into jelly, jams, and pies. The juice may be fermented into wine. Green berries, sap, and stems are toxic and, when not cooked, the calcium oxalate crystals they contain may damage to human kidneys.

Elderberry prefers an average moist compost rich soil in full to partial sunlight. The soil pH should fall between 6.0 – 6.5. Fertilize at 6 – 8 oz of 10-10-10 fertilizer annually per shrub in early spring.

Shrubs tend to grow rapidly and may require a hard cutback every 2-3 years to restrict plant size and the aggressive suckering root system. Elderberries are generally maintained at 6-8 feet in height, but may be pruned shorter to accommodate a small garden patch. Plants should be set 5-6 feet apart.

Potential pest problems, such as powdery mildew, stem dieback, rust, leaf spots, viruses and insect borers, are best managed through judicious pruning in early spring.

Horticultural varieties include: ‘Adams’, ‘Johns’, ‘Nova’, ‘New York 21’ and ‘York’. Plant two or more different varieties for greater fruit yields.

Growing Table Grapes in the Eastern U.S.

Posted by Hugh on December 1st, 2011

Grape Growing at Callaway Gardens

Gardeners in Southern Appalachian region (USDA zones 6 and 7) can now grow seedless table grapes. “The quality of the new table grape varieties is terrific, rivaling those we currently buy at our local supermarkets from California”, according to Dr. David Lockwood, Universities of Tennessee and Georgia Extension Fruit Specialist.

Eastern table grapes are hybrids of V. vinifera and V. labrusca. V. labrusca provides better winter hardiness, reduced disease susceptibility, and a fruity or “foxy” flavor similar to the old seeded variety ‘Concord’. The berry texture is crisp like the non-slipskin V. vinifera sold in supermarkets.

His recommended list of hardy table grapes includes:

‘Jupiter’ – large reddish blue (blue at fully maturity); flesh is semi crisp, thin skinned; harvest in late July.

‘Neptune’ – medium white (yellow-green skin) fruity and pleasant; harvest in early September.

‘Saturn’ – medium red berry with a sweet and fruity flavor; harvest in late July.

‘Vanessa’ – firm red berries with a fruity taste; stores well after harvest; ripens in early to mid September.

‘Marquis’– is slip-skin type having an excellent Labrusca fruity flavor; ripens in early to mid September.

The new varieties were developed at the Geneva Experiment Station in New York State, and Arkansas Experiment Station in Fayetteville, AR, and the Vineland Experiment Station in Ontario, Canada.

These grape varieties are susceptible to serious foliar fungal diseases as black rot, downy, powdery mildews and anthracnose. They require timely fungicide controls in the spring and summer months.

Thujopsis: Semi-Dwarf Evergreen Shrub

Posted by Hugh on November 28th, 2011

10-year old Thujopsis dolobrata on ETSU Campus in Johnson City, TN

Hiba or false arborvitae (Thujopsis dolobrata) is a slow to moderate growing evergreen shrub or tree. It is also called elkhorn cedar and deerhorn cedar, referring to the shape of its scale-like leaves. Tall 50-80 feet tall tree forms arefound in the forests of Japan.

Underside of needles

This native of Japan and China has a pyramidal form and beautiful dense foliage, similar to arbovitae (Thuja spp.). The scale-like bright or dark green leaves are arranged in flattened sprays with white markings beneath. Its reddish-brown peeling bark adds to the plant’s appeal. Small 3/4 inch cones provide little ornamental value. A notable tree form occasionally available from U.S. nurseries is ‘Hondai’; it grows much shorter at 30 – 35 feet in height with dense sprays of dark green foliage.

False arborvitae grows best on a moist well-drained site in full sun or bright shade . Occasional watering is recommended in severe summer/fall dry periods. False arborvitae needs to be sheltered from dry winter winds.

Winter foliage color may vary by location and cultivar planted. In Southern Appalachian Region (USDA zones 6 and 7), winter foliage takes on a muted olive-green tone.

Two most popular dwarf clones are:

‘Aurea’ – a dense shrub with golden yellow foliage; grow in light shade.
‘Nana’ – a slow growing, dwarf mounding form with good plant symmetry; its wintry foliage takes on a silvery tint.

A 10-year old ‘Aurea’ or ‘Nana’ thujopsis grows 3 to 4 feet tall and 5 to 6 feet wide.

False arborvitae is hard to find in the nursery trade, available thru e-commerce specialty nurseries.

Autumn Colors Conclude with Callery Pears

Posted by Hugh on November 23rd, 2011

'Bradford' Callery Pear in Fall Color

Callery pear (Pyrus calleryana) has been declining in planting popularity. But its scarlet red leaf color is both sensational and reliable every autumn in the Southern Appalachian region (USDA zones 6 and 7). Most people identify the tree by its cultivar name, e.g. ‘Bradford’, Aristocrat®, ‘Cleveland Select’, ‘Redspire’ pear. There are many other cultivars.

Callery pears are tough reliable medium sized trees which mature to heights from 30-50 feet. Mature tree widths vary from one cultivar to the other. Callery pears transplant and grow well in any soil type as long as it is well drained. Callery pears are excellent choices for planting in new treeless neighborhoods, the ground mostly consisting of marginal subsoil. Just add the proper amount of fertilizer, such as 10-10-10 or equivalent, and irrigate during the first two summers.

Cultivars vary in their susceptibility to fireblight, a serious bacterial disease. Bradford and Cleveland Select are very resistant and Redspire and Aristocrat are very susceptible. When fire blight strikes, numerous dieback shoots must be pruned off, gathered, and hauled away from the property. Do not attempt to compost the diseased shoots.

The “cookie-cutter” upright branching form is their Achilees’ heel. It is subject to limb breakage, beginning in 12-14 years after planting. Bradford is most susceptible and Aristocrat and Cleveland Select less so.

Autumn foliage colors may be waning, but Callery pears will be blooming again in early spring.

‘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.