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

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.

Fall Blooming ‘Little Suzy’ American witchhazel

Posted by Hugh on November 7th, 2012

Hamamelis virginiana 'Little Suzie' in October '12

Little Suzy American witchhazel (Hamamelis virginiana ‘Little Suzy’) was hybridized and introduced by Harald Neubauer, owner of Hidden Hollow Nursery in Belvidere, TN. This medium sized shrub grows 8-10 feet tall and 10-15 feet wide. It is particularly suited to small urban gardens where standard American witchhazels (20-25 feet in height and width) are too large. Little Suzy’s short compact nature is due to its shorter internode lengths.

Little Suzy blooms freely at a young age. The witchhazel-scented soft yellow blooms appear in October and November in the Southern Appalachian region (USDA hardiness zones 6 and 7). The 4- narrow, strap-shaped yellow petals appear at a time of year when little else is blooming.

New leaves emerge reddish-bronze in early spring and turn dark green. Summer leaves are dark green and remain blemish-free from disease and pest woes. Foliage stays clean and pest-free throughout the growing season. The 3 to 6 inch long coarsely toothed leaves turn clear yellow before falling in late autumn.

American witchhazel is not finicky where it grows, either in full sun to partial shade. It prefers moist, acidic, and well drained soil, but a 2-year established shrub exhibits good heat and drought tolerances. Their “popcorn” like seed capsules can disperse seeds 25 feet or more away.

American witchhazel is utilized as a fall blooming oddity or plant several together for a deciduous hedge or privacy screen. Through judicious pruning a shrub can be shaped into a lovely small tree.

Little Suzy witchhazel is available from specialty plant nurseries on-line.

American Elm Is Back

Posted by Hugh on November 2nd, 2012

American elm in woodsy landscape near Knoxville, TN

American elm (Ulmus americana) once lined America’s city streets until the deadly Dutch elm disease (DED) mostly eliminated it. DED is still present today. Outstanding disease resistant cultivars are truly making a difference, and American elm is on the comeback.

American elm is native to the eastern and central regions of the U. S. and southern Canada (USDA hardiness zones 3 to 9). American elm are related to hackberry (Celtis spp.) and zelkova (Zelkova spp.). There are many species of elm worldwide. Its arching vase shape branching habit is its trademark trait, and this large tree averages 60 to 80 feet in mature height and 25-30 feet in width.

Compared to other landscape trees, American elm is one of the earliest to flower, often in late winter in the Southern Appalachian region (USDA hardiness zones 6 and 7). By late May flowers have set small circular winged seeds (samaras) which float by wind over long distances. Seeds germinate rapidly under favorable conditions.

American elm grows in moist deep soils and full to partial sunlight. It copes with dry average soils, is mostly soil pH insensitive, and tolerates high soil salt levels better than most tree species. Elm withstands brief flooding episodes in spring and fall. Prune elm from mid-summer into fall when potential pest problems are minimal and the internal sap flow is low.

The first line of defense against Dutch elm disease is planting resistant cultivars. American elm is also susceptible to deadly phloem necrosis disease, with symptoms similar to Dutch elm. Elms are subject to numerous insect pests, but rarely threaten their long time survival.

Among the best resistant cultivars with true American elm bloodline, ‘New Harmony’, ‘Valley Forge’, ‘Washington’, and ‘Jefferson’ stand out. Among the Asian – American elm hybrids, ‘Morton’ (Accolade™) is a recommended choice. Accolade elm is also resistant to elm leaf beetle feeding.

Blue Mist (Caryopteris) Sparkles in Late Summer Garden

Posted by Hugh on October 31st, 2012

Caryopteris x clandodensis

Blue mist spirea or bluebeard (Caryopteris x clandodensis) is not commonly planted in U.S. landscapes. In mid- to late- summer, pale blue flowers open above the gray-green foliage. Leaves and stems are mildly aromatic to the touch. There are now several good hybrid forms, thanks to plant breeders’ efforts to improve garden performance.

Caryopteris (I prefer this name) grows in average soil, preferably slightly acidic, and wants very little extra care. Although moderately drought tolerant, don’t allow it to suffer through a prolonged dry spell without irrigation. Cold hardy to USDA hardiness zone 5 (perhaps 4 with some protection), branch tips may die back 30-40% over winter.

Some plant experts classify caryopteris as a hardy perennial and treat it as such. Shoot injury may become noticeable in early spring, necessitating pruning. The easiest solution is to severely prune back the entire shrub in late winter.

This shrub recovers rapidly from cutting back. The technique is simple, not time saving, and doesn’t require reading a pruning book. It results in a compact growing, space-saving shrub.

Caryopteris may open hundreds of blooms at any time over a 6-8 week period from late summer into fall. Caryopteris suffers from very few disease and pest problems, including deer feeding.

Its flowers and gray-green foliage (select varieties) are prized by florists who utilized them in fresh and dried flower arrangements. Fresh keeping quality often lasts 7 days and longer.

Many hybrid cultivars are available, including two favorites:

‘Worcester Gold’ – solid gold foliage and pale blue flowers.

‘Dark Knight’ – deep blue flowers on 3-4 foot compact plant.