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

Trifoliate Orange –The Barbed Wire of the Plant World

Posted by Hugh on December 12th, 2011

Winter View of Trifoliate Orange

Trifoliate orange (Poncirus trifoliata) is a hardy citrus native to China. T-orange is hardy to -15° F. This strong growing large shrub or small tree can reach 15 to 20 feet in height. Its foliage is deciduous and compound, compared to citrus trees with single simple evergreen leaves.

T-orange prefers full day or partial (minimum of 6 hours) sunlight. After one year establishment, it can cope with moderate periods of drought. T-orange grows in a soil pH range between 6.2 to 7.5 in average well-drained soils. One 3-4 oz. annual application of 10-10-10 granular fertilizer per plant in late winter provides adequate nutrition.

Showy 1 ½ to 2 inch white, mildly fragrant flowers open from late April into early May in the Southern Appalachian region (USDA zones 6 and 7). Golf ball sized green fruits turn rusty yellow (not orange) in late summer and are quite aromatic. The bitter fruits are edible and loaded with seeds.

Numerous heavy- duty, 1-2 inch long spines (thorns) form along deep green stems. The dominant spines seem to attract plant buyers to this “Little Shop of Horrors”. Plant it as a hedge to deter trespassers, if that is something you need to do. Aggressive pruning or shearing shapes and limits its size, but be advised to wear thick protective gloves and pack some extra band-aids.

T-orange is used as a winter hardy rootstock in commercial citrus groves. Some concern has been raised of its potential invasiveness.

‘Flying Dragon’ is a dwarf form with stems and thorns contorted or twisted. It grows well in pot culture.

Key Points About Growing Peaches

Posted by Hugh on December 8th, 2011

Flowering peach in Early Spring Garden

People think peaches grow only in Georgia. A decade long period of mild winters in the Southern Appalachian region (USDA zones 6 and 7) have increased gardener confidence in growing peaches. Peaches (Prunus persica) tend to flower in early spring, when the threat of spring frost is high across the region. In many years spring frost may kill 80% of their flower buds, but still manage to produce a full crop in July or August.

Standard peach trees grow and are easily maintained through pruning at 10-12 feet in height. Do not plant dwarf peach trees as they live only a short time and are not worth their cost. Dwarf root systems for peaches are weak and break off from the graft union within a few years.

Select only cold hardy, great tasting peach varieties. The finest freestone peach varieties with long winter chilling requirement are listed below. If you garden in zone 7-a or further north, these are suited for your area. Freestone peaches are great for eating, baking and canning; the flesh does not stick to the pits. Clingstone peaches are also sweet and tasty.

Table 1. New peach varieties and approximate harvest times in East Tennessee and Southwest VA (zone 6-b):

3^rd week July Contender (yellow flesh, freestone)

4^th week July Nectar (white flesh, freestone)

1^st week August Carolina Gold (yellow flesh, freestone)

2^nd week August China Pearl (white flesh, freestone)

Late August Intrepid (yellow flesh, freestone)

Table 2. Older reliable varieties for East Tennessee and Southwest Virginia include:

Cresthaven (medium to large fruit, yellow flesh, freestone)

Jefferson (early season, medium yellow-orange flesh, freestone)

Monroe (late harvest, medium yellow flesh, freestone)

Red Haven (medium, nearly fuzzless, yellow flesh, freestone)

Credit: Dr. David Lockwood, Extension Fruit Specialist at the Universities of Tennessee and Georgia, recommends these varieties.

Disease Free Apple Varieties

Posted by Hugh on December 6th, 2011

Apple Selection at Local Supermarket

Over the past 30 years, the goal has been to develop good eating and storing apples which are not susceptible to four major diseases. The first 3 cultivars released were ‘Prima’, ‘Priscilla’, and ‘Sir Prize’, but they lacked great flavor and storage quality.

Apples are susceptible to four serious diseases: apple scab, cedar-apple rust, fireblight, and powdery mildew. Scab, rust and mildew foliar diseases required a rigorous fungicide spray routine every 7-10 days from spring petal fall up to harvest. Fireblight is a bacterial disease without any satisfactory control measures other than pruning off dead twigs and branches.

Gardeners are looking for better non-pesticide (organic) options. Here are 5 “no-spray” disease resistant varieties:

‘Liberty’ – McIntosh type flavor with good to moderate resistance to all 4 diseases.

‘Freedom’ – crispy, slightly tart red medium to large fruit for both eating, cooking and juice; 3 month storage life.

‘Goldrush’ – crispy, nearly ‘Golden Delicious’ in flavor, slightly tart; good keeping quality; susceptible to cedar apple rust.

‘Enterprise’ – new sprite tasting red skin/white flesh variety with good keeping quality after harvest.

‘Arkansas Black’ – old timey variety with good disease resistance; tart apple whose flavor improves after 1 month in storage; long keeping time; skin color turns almost black.

The development of disease resistant cultivars has greatly diminished the number of fungicide sprays required to grow a successful crop. Insect control is still needed.

Credit: Dr. David Lockwood, University of Tennessee Fruit Specialist suggested these 5 disease resistant varieties.

Everbearer Raspberries Harvest from July To Frost

Posted by Hugh on December 5th, 2011

: Raspberry Production at Biltmore Estate, Asheville, NC

Everbearer raspberries are easier to grow compared to the June-bearer types. Everbearer types are often called “fall bearers” because they produce berries from very late July to late September. Pruning becomes a simple chore – in late winter simply cut down all canes (shoots) to the ground. The traditional June crop is lost, but the new spring canes produce a large summer- fall crop.

Fall bearers grow best in full sun and in well-drained soil. Raspberries prefer a soil pH of 5.6 to 6.2. Drip irrigation over the summer months is needed to keep plants stress-free during incessant summer heat and drought periods. Mulching also aids in weed prevention and retaining soil moisture. In March and May apply one pound of 10-10-10 garden fertilizer per 100 square feet of bed. Do not fertilize in summer.

For backyard fruit enthusiasts grow raspberries on raised beds. Construct a sturdy trellis for cane support during the summer. This keeps most of the fruit off the ground and easier to pick. Trellis should be strongly built to handle the heavy yields starting in the 3^rd season. The canes will bend down the support wires.

‘Caroline’, ‘Nantahala’, ‘Autumn Britten’, ‘Fall Red’ and ‘Heritage’ are reliable red everbearer varieties. ‘Anne’ and ‘Fall Gold’ are golden tinted red everbearer berries. Fall bearing raspberries are easily available from on-line e-commerce nurseries. Purchase only rooted canes which are certified disease-free.

A patch of raspberries provides many years of healthy and luscious fruits, high in fiber and loaded with minerals, vitamins, anti-oxidants, and anti-carcinogens.

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.