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

Two Sensational New Oakleaf Hydrangeas

Posted by Hugh on January 24th, 2011

'Ruby Slippers' oakleaf hydrangea

Oakleaf hydrangea (Hydrangea quercifolia) is a popular native shrub in the Southeastern U.S. (USDA hardiness zones 5 to 8). Two new compact forms of oakleaf hydrangea were recently introduced by the U.S. National Arboretum.

In early summer, ‘Ruby Slippers’ is covered with 9-inch-long floral clusters that are held upright above the foliage. ‘Ruby Slippers’ grows to about 3 ½ feet tall and 5 feet wide and has large creamy white flower panicles that mature to a deep rose color in late summer. ‘Munchkin’ is slightly smaller at 3 feet tall and 4 ½ feet wide, and 6 ½ inch long white flowers age to a medium pink color. Both cultivars grow in either light shade or full sun.

Their compact form and dense plant habit make it ideally suited for use in small residential landscapes. The new light green foliage in spring turns dark green in summer and mahogany-red in fall. Both are ideal specimen shrubs planted either individually or together as a lovely deciduous hedge row.

‘Ruby Slippers’ and ‘Munchkin’ were developed by Dr. Sandra Reed, plant breeder at the U.S. National Arboretum Research Lab, located at the Tennessee State University Nursery Research Center in McMinnville, TN.

2012 Perennial Plant of the Year Named

Posted by Hugh on January 21st, 2011

Brunnera 'Jack Frost'

The Perennial Plant Association (PPA) has selected Brunnera macrophylla ‘Jack Frost’ as the 2012 Perennial Plant of the Year. Runnersup for 2012 honors were Panicum virgatum ’Northwind’, Heuchera ‘Caramel’ and Chelone lyonii ‘Hot Lips’.

Brunnera ‘Jack Frost’ foliage is deer resistant. It grows to a height and width of 12-15 inches. Its silvery foliage stands out in a shade garden. Brunneras produce racemes of blue star-like flowers in mid to late spring.

Grow ‘Jack Frost’ brunnera in a compost-rich, well-drained soil. Water plants regularly during summer dry spells. Mulching around plants also benefits.

Brunnera inhabits the shade garden alongside other favorites such as hostas (Hosta spp.), lungworts (Pulmonaria spp.), coralbells (Heuchera spp.) and variegated Solomon Seal (Polygonatum odoratum ‘Variegatum’).

Brunnera ‘Jack Frost’ was commercially introduced in 2000 by Walters Gardens in Zeeland, Michigan.

Reminder: The 2011 Perennial Plant of the Year is Arkansas Bluestar (Amsonia hubrichtii)

Stop the Leyland Madness

Posted by Hugh on January 18th, 2011

Leylands Gone Wild!

Leyland cypress (x Cupressocyparis leylandii) is a tall, fast growing evergreen tree or shrub. Many are planted as privacy screens. Ask yourself, should you really plant a 50 foot barrier between you and your neighbor(s)?

In the Southern Appalachian region (USDA hardiness zones 6 and 7), there are shorter and better evergreen choices. In the 12-16 foot category:

Boxwood (Buxus spp. and hybrids)

Plum yew (Cephalotaxus harringtonia) ‘Fastigiata’

Hinoki cypress (Chamaecyparis obtusa)

Japanese falsecypress (Chamaecyparis pisifera)

Dwarf Burford holly (Ilex cornuta ‘Dwarf Burford’)- clipped

Inkberry (Ilex glabra)

Foster holly (Ilex x attenuata)- clipped

American holly (Ilex opaca)- clipped

Nellie R. Stevens holly (Ilex x ‘Nellie R. Stevens’)- clipped

Skip laurel (Prunus laurocerasus ‘Schipkaensis’)

Yew (Taxus spp.)- upright or fastigiate forms

Eastern arborvitae (Thuja occidentalis)

Leatherleaf viburnum (Viburnum rhytidophyllum)

Prague viburnum (Viburnum x pragense)

Leyland cypress is susceptible to three serious canker diseases, in which pruning is the principal curative remedy. Leyland is also susceptible to bagworms. Their enormous growing height makes pesticide spraying and pruning options almost impractable and costly.

From the start, don’t plant leylands closer than 12 feet apart (recommend 16 feet spacing). Plants will touch within 4 years after planting. During the first three summers, young leylands require deep watering as they’re not drought tolerant. A 2-3 inch mulching depth in the row aids in conserving soil moisture.

Planting Trees for Future Generations

Posted by Hugh on January 15th, 2011

A Lovely Blackgum in Winter

Oaks, beeches, hickories, ginkgoes, bald cypresses, redwoods, chestnuts and others are trees that future generations inherit from previous generations. In human terms, it takes a lifetime to grow an acorn into a mighty oak. Many tree species live hundreds of years, often asking little and contributing much beauty, summer cooling shade, winter heating comfort as windbreaks, and a food source for birds, insects, and other animals.

Select seeds from trees of exceptional parent stock. You may want to collect acorns around an historical site, such as Andrew Jackson’s Hermitage near Nashville, TN or Thomas Jefferson’s Monticello just outside Charlottesville, VA. Pick seeds or nuts from a parent or grandparent’s property.

If you are asked to serve on a tree planting project this spring, do volunteer, not only at digging time, but on the summer maintenance detail. Young trees need nurturing as do young children. When summer is at its hottest and driest, you should be standing by the tree(s) with hose in hand. Apply or refreshen the mulch around the tree(s) to reduce potential weed competition and also to conserve soil moisture.

Frequently, the concept of “mightier than an oak” begins in the mind and caring hands of a gardener like yourself.

Hardy Dwarf Deodara Cedars

Posted by Hugh on January 13th, 2011

'Glacier Blue' Deodara Cedar

Over the past ten years, deodara cedar (Cedrus deodara) has carved its niche into Southern Appalachian gardens (USDA zones 6 and 7). Three zone 6 hardy dwarf cultivars, ‘Glacier Blue’, ‘Devinely Blue’, and ‘Feelin Blue’, fit today’s smaller garden space better than most tree forms of deodara cedar that typically reach 70-80 feet in height. All three sport lovely soft blue-green foliage.

Deodara grows best in full sun to light shade in moist fertile, well-drained soil. Deodara needs good air movement to prevent problems with needle diseases. New deodaras require regular watering during summer dry spells. All three cultivars make great accent plants among large boulders, other dwarf conifers, and rockery plants.

‘Glacier Blue’ grows 5-8 feet tall in ten years. Growth rate is moderate with a spreading to slightly pendulous arching form.

‘Devinely Blue’ grows only 3-6 inches annually. It matures into a 6 feet tall and 3 feet wide shrub. New spring foliage starts out gray-green and turns bluish green.

‘Feelin Blue’ exhibits a prostrate growth form similar to ground cover junipers. At maturity it reaches 3-4 feet in height and 6-8 feet in spread.

Winter Care of House Plants

Posted by Hugh on January 10th, 2011

: Lovely Foliage Plants at Grove Park Inn in Asheville, NC

Most plants adapt to winter’s shorter daylength and low light intensity. Interior plants require less water and nutrients. Plants also adapt to the lower room humidity in our modern day homes. Grouping plants together and spritzing them 1-2 times a day is helpful.

Soil moisture needs varies with the type of plants and the kind of containers (plastic, clay or ceramic). How long has the plant been in the same pot or planter? Plastic and ceramic pots retain soil moisture longer than clay pots.

I urge gardeners to adopt a simplistic house plant care approach. Fit plants on your everyday schedule. Make watering part of the Saturday morning chores or after Sunday church services or prior to Sunday game kickoff. Water 1-2 times weekly. If some plants don’t need water, skip them.

As winter wanes, tackle the job of re-potting those plants that have not been re-potted in one year. Gently shake off some old potting mix and transplant into a slightly larger container and new soil-less media.

Beginning March 1st, feed plants every 2-3 weeks. Most branded “house plant” fertilizers work well. My personal tip is to decrease recommended label amounts by half, and fertilizie plants twice as often from March through October.

Be vigilant about bugs and diseases. Simply washing the foliage with a mild dish washing soap, insecticidal soap or miscible oils can clean off most pest problems. Frequently, pest problems can be resolved without using inorganic pesticides.

Winter King Hawthorn – A Winter Fruit Attraction

Posted by Hugh on January 7th, 2011

: bright red fruit in winter season

‘Winter King’ is an outstanding cultivar of our native green hawthorn (Crataegus viridis) and is at home here in the Southern Appalachian region (USDA zones 6 and 7). Over the winter season few deciduous trees present a colorful fruiting display much better than Winter King.

Winter King hawthorn is a small landscape tree, maturing to 25-30 feet tall and wide in twenty years. Its medium green glossy leaves are small in size and are rarely disfigured by disease and insect problems when planted in the right landscape environment.

Winter Green grows best in a well-drained loamy soil and in full sunlight. Autumn foliage does not stand out, turning yellowish green before falling. A 3- year or older tree is exceptionally summer heat and drought tolerant.

Winter King flowers in mid-spring, usually right after ornamental crabapples, which novice gardeners often confuse with hawthorns. Individual flowers are 5-petaled and tend to be malodorous. The silvery green branches bear sparse numbers of one inch long thorns.

Winter King bears a bountiful annual crop of 1/2 inch diameter green fruits which turn bright red in the fall. They serve as a plentiful food source for winter-feeding birds and other wildlife. Deer rarely feed on the prickly branches.

As the tree ages, bark on central trunk and major scaffold branches chips off in small pieces exposing a tan to orange inner wood.

Hardy Camellias — start with this one!

Posted by Hugh on January 4th, 2011

Occasionally, gardeners need abit of confidence before purchasing a plant considered not winter hardy where they live. Twenty years ago, growing a camellia was a folly inside the Southern Appalachian region (USDA zones 6 and 7), until the Drs. Ackerman and Parks’ introductions appeared. These hardy cultivars have changed the playing field.

Recently, I asked some local camellia “experts” what one favorite cultivar gardeners should start with. While none wanted to go on record as picking just one, ‘Pink Icicle’ (pictured) appeared on everyone’s long list. One landscaper stated that he planted ‘Pink Icicle’ in an open full sun garden area of a cemetary ten years ago and all have prospered.

‘Pink Icicle’ blooms nearly two months in March and April from New York, NY, southward and westward to St. Louis, MO. It sports a glossy dark green foliage which is better looking than most fall blooming cultivars. Choose a garden location where the camellia is protected from mid-afternoon summer sun and blustery winter winds.

The culture of camellias is similar to rhododendrons and azaleas. A camellia established for two or more years in its garden space exhibits above average drought tolerance.

Recycle Live Christmas Trees

Posted by Hugh on December 30th, 2010

Ready for Recycling

The holidays are over. This year take your live Christmas tree to a designated location to be recycled. Many cities and towns collect trees which are chipped into mulch. The mulch is spread around municipal park trees and street trees. It is utilized for erosion management along stream banks and on steep slopes. Mulch is also distributed to gardeners in the spring.

Communities pile up recycled trees as protective habitats for birds and other wildlife. Whole trees may be deposited into lakes and ponds as fish habitats, particularly for bottom feeders. Along fragile coastal areas trees are used to protect and restore dune areas.

Recycled trees protect newly planted young saplings from severe winter winds and serve as snow breaks in forests and park plantings. They also prevent deer and other varmints from feeding on newly planted tree seedlings.

Regarding trees to be recycled, here are a few caveats:

Remove the stand and all decorations (lights, tinsel, ornaments, plastic garland, all metal items)
Whether recycled or for curbside pickup, don’t wrap tree in a plastic bag

Many local communities advertise special drop-off points or collection times for discarded holiday trees. Check your local newspaper, city website or community recycling center for information. If tree recycling is not offered, maybe you and some friends can help organize one.

Ice Storm- Keep Hands Off

Posted by Hugh on December 26th, 2010

Ice Coating over Lacebark Pine

An ice storm is both a beautiful and horrific scene in a garden. The potential for major tree/shrub breakage is staggering. If you feel powerless, this is good thing. During the storm, do nothing / “hands off”. Most actions will likely cause more damage than what nature may have intended.

After the storm assess the landscape areas which seem most vulnerable, or that trouble you most. Next, hire an ISA* certified professional arborist to fit your landscape into his/her schedule. At the time of the storm, arborists are likely much too busy with emergency callers.

First on your list should be large trees not pruned in many years. They are likely shedding diseased, pest ridden, or broken limbs. Weak wooded species like silver maple (Acer saccharinum), sycamore or planetree (Platanus spp.), Bradford pear (Pyrus calleryana), poplars (Populus spp.), and willow (Salix spp.) seek to always drop anything from small twigs to large branches. Large evergreens like white pine (Pinus strobus) and leyland cypress (Cupressocyparis x leylandii) frequently deposit broken branches following stormy weather.

Ironically, the trees suffering the worse damage are those topped by neighbors and utility companies. The re-growths are very weak and snap off when the ice load reaches critical mass. Properly pruned trees ride out most ice storms. Take care of your trees and trees take care of you.

*International Society of Arboriculture