Friday, July 28, 2017

Plant Spotlight: Swamp Milkweed (Asclepias incarnata)

Asclepias incarnate. Swamp milkweed can be used in rain gardens and stormwater gardens to filter pollutants and support monarch butterfly habitats. Photo by myiarchus22, CC BY-NC-2.0

Swamp milkweed (Asclepias incarnata) is a native, perennial and toxic pink wildflower plant found in swamps, shores, thickets; marshes, moist meadows. Asclepias is the milkweed family of wildflowers essential as a monarch butterfly food source. The swamp (incarnata) variety of milkweed can be grown in urban rain gardens and other residential areas prone to poor drainage.
Erect, perennial herbs with milky juice; leaves simple, alternate, opposite, or whorled, narrow; flowers 5-parted, in rounded clusters, white, greenish, yellow, orange, or red; fruit dry and inflated, erect, and with many hair-tufted seeds
Growing Season:
Early to late summer
2-4 ft.
Up to 4-inch, opposite, narrow, lance-shaped, smooth leaves; milky sap is less juice than most species; short-stalked to stalkless
1-to 2-in., dull pink flowers, clustered at the top of a tall, branching stem; five recurved petals; elevated central crown, divided
Weedy in disturbed areas, native or naturalized in waste places, roadsides, fields; landscape in flower gardens as herbaceous perennials
All parts of this plant are poisonous if ingested. Symptoms include vomiting, stupor, weakness, spasms. The toxic principle is cardiac glycosides and resinoids. TOXIC ONLY IF LARGE QUANTITIES EATEN.

Sunday, July 23, 2017

BOOKS: JC Raulston Arboretum Director's "Gardening in the South"

Gardening in the South: The Complete Homeowners Guide
Author: Dr. Mark Weathington
Publisher: Timber Press (2017)
Format: Paperback
Pages: 320 pp.
Images: 397 color photos
ISBN-10: 1604695919
ISBN-13: 9781604695915

Extension Specialist, Urban Horticulture
NC Cooperative Extension
Learn from a pro, MARK WEATHINGTON is director of the JC Raulston Arboretum at North Carolina State University. His more than twenty years of experience gardening in the South include serving as a horticulturist for the Atlanta Botanical Garden and director of horticulture for the Norfolk Botanical Garden.

He packs decades of wisdom into this definitive handbook sharing exactly what it takes to grow your dream garden in the South including everything from a comprehensive A–Z guide of the best plants for the region to how to work with southern climates, seasons, and soils.

Pore over design ideas for all types of outdoor spaces, and follow a quick-glance, year-round maintenance chart tailored to southern specifics.

 Filled with insider tips, this go-to manual should be on the shelf of anyone who gardens in the unique conditions of the South.

Sunday, July 16, 2017

Flower Show School: Course I in Advance, NC

AUG 21-23, 2017

The Flower Show School is open to all who desire to enrich their knowledge of horticulture, design and flower show procedure. This national certification program is managed by the National Garden Clubs, Inc.

Course I is sponsored by Winston-Salem Judges Council and will be held at the Hampton Inn Advance, in Advance, NC.
Register by July 24, 2017 by using the this brochure: 

Full Certification Schedule:
  • Course I:   August 21-23, 2017
  • Course II:   March 12-14, 2018
  • Course III: September 17-19,2018
  • Course IV: April 15-17, 2019

Saturday, July 8, 2017

Summer Shade with Live Oaks in the South

Take cover in the shade under a Quercus virginiana this summer!
Tours in Louisiana are available:
Photo: Plantation Balcony view from Oak Alley Plantation in Vacherie, LA. Photo by J.S. Corser, Durham Co. Master Gardener.

Clemson University Extension Consumer Horticulture
HGIC 1014
The Live Oak

The live oak (Quercus virginiana) is the principal evergreen oak in South Carolina. Although it is adapted to all of South Carolina, it favors conditions along the coast, where it grows wild. The full development of the live oak in South Carolina can be expected only within the warm, humid environment of its natural range. It tolerates cold extremes up through the Piedmont (not the mountains), but will grow more slowly and may suffer from ice storm damage.

Mature Height/Spread
Live oak is rounded and wide spreading, growing 40 to 80 feet tall and 60 to 100 feet wide. In the forest it stands erect, growing 100 feet tall, but in open landscapes the sprawling horizontal branches arch to the ground and form a broad, rounded canopy.
Growth Rate

This tree grows moderately fast in youth, producing 2 to 2½ feet of growth per year if properly located and maintained. Trees grown outside the coastal region will grow more slowly. The growth rate also slows with age. One of the longest-lived oaks, it may live 200 to 300 years.

Ornamental Features
The live oak is probably best known for its massive horizontal limbs that give old trees their majestic character. The trunk can grow to more than six feet in diameter. The leaves remain intact through the winter, then yellow and drop in spring as new leaves expand. Trees growing further inland, however, become semi-evergreen, losing some leaves in fall and winter. The waxy leaves are resistant to salt spray.

Live oak (Quercus virginiana) leaves and acorns.
Lindsay Caesar, Horticulture Department, Clemson University.
The small (1 inch) acorns are dark brown to black when ripe, and are primary food for many wildlife species along the coast. They are produced in clusters of one to five.

Live oak is susceptible to leaf blister, a fungal gall that disfigures leaves but does no appreciable harm. Several insect galls are also found on live oak. No control is available. Oak wilt is a serious fungal disease that can kill infected trees within a year or two of infection. This disease occurs in only six counties in South Carolina: Chesterfield, Kershaw, Lancaster, Lee, Darlington and Barnwell. For more information on problems of oak, refer to the fact sheet HGIC 2006, Oak Diseases & Insect Pests.

When grown in the South Carolina Piedmont, outside of their natural range, live oaks may be injured or killed by cold temperatures or ice storms. For this region, select cold-tolerant cultivars or seed-propagated live oaks with proven cold hardiness.

Landscape Use
Live oaks are reminiscent of the Old South, especially when planted along avenues or drives leading to old plantations. Although used extensively for street tree plantings, in time the roots will lift sidewalks or streets if planted too close. It will do well as a lawn specimen provided it is given plenty of space.

Although it responds best to plentiful moisture in well-drained, sandy soils, it tolerates drier, more compacted sites. Once established, it is drought-resistant. It prefers sun but tolerates more shade than other oaks because its leaves function throughout winter.

Pruning is only necessary to develop a strong branch structure early in the life of the tree. It should be trained with a central leader. Eliminate young multiple trunks and branches. Prune in mid-to late summer to avoid oak wilt disease.

Cultivars & Varieties
  • Highrise® - This was the first patented cultivar of live oak. It was discovered as a seedling growing in Orangeburg, SC. It has a uniform, upright pyramidal growth habit with a mature height and spread of 30 to 40 feet and 12 to 18 feet, respectively.
  • Cathedral Oak™ - This cultivar has a pyramidal canopy when young that becomes broad to ovoid as it matures. It is expected to have a mature height and spread of 40 to 80 feet and 60 to 120 feet, respectively.
  • Millennium Oak® - This cultivar has the traditional, picturesque growth of live oak and has a predictable growth rate and habit. Expect a mature height of 50 to 75 feet and a spread of 60 to 100 feet.
Revised by Bob Polomski, Extension Consumer Horticulturist, Clemson University, 02/14. Originally prepared by Debbie Shaughnessy, HGIC Information Specialist, and Bob Polomski, Extension Consumer Horticulturist, Clemson University. New 05/99; Images added 11/06 & 12/15.

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2017 Gardeners' Advice Fair: July 25

Bring all of your gardening questions to the Gardeners Advice Fair!
Experts will be on hand at Duke Gardens from 6:30-8 p.m. on Tuesday, July 25, 2017.

GCNC Fall Board Meeting in Cary: Sept. 10-11

Saturday, July 1, 2017

July Calendar of Triangle Gardening Programs

July is busy with many educational and fun gardening programs across the Triangle!
See a a comprehensive listing from Triangle Gardener magazine: