Boxwood blight

StevensCaryYoest (61)

 

I try not to worry about too much in the garden, it’s pleasure central for me. My personal design aesthetic is that of wild abandon framed in formal boxwood hedges. So you can imagine how upsetting it was to hear of a boxwood blight making its way to North Carolina Landscapes.

Photo credit Kelly Ivors

Photo credit Kelly Ivors

The blight is caused by the fungus Cylindroclaidium buxicola. Researchers at North Carolina State University are learning which boxwood species are most susceptible and which ones can withstand the fungus. I hope they find that mine will be fine.
According to Dr. Kelly Ivors, an associate professor of plant pathology and specialist with the North Carolina Cooperative Extension, “The two most commonly planted cultivars in the United States – the American boxwood and the English boxwood – are by far the most susceptible, Ivors said, because they lose  the most amount of foliage when exposed to the fungus. On the plus side, Ivors also said that her department tested 23 other varieties and several tolerated the fungus.
The good news? The nursery industry is working to keep the blight away from the customer by destroying infected plant. Disease symptoms include dark or light brown circular spots, often with dark edges, on the leaves, as well as dark streaks in stems, and off colored leaves.

When buying plants, check for disease symptoms. Your local independent garden center will be informed to the problem. If you suspect any, let the owner know.

“I don’t want to discourage people from buying boxwood,” Ivors said, “but we need to educate the green industry and their clientele to let them know what box blight looks like so we can limit the disease from becoming established.”
If homeowners suspect that their boxwood plants have the disease, they can submit samples to the N.C. State University Plant Disease and Insect Clinic. The testing is free for those who follow guidelines outlined at HERE. For more information on the disease, its symptoms and management, including information on the cultivar susceptibility trial,  check out this link.

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Tarheel Gardening–Wordless Wednesday


Clematis

Tarheel Gardening: the best in nurseries for gardening and landscaping in North Carolina.

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Oakleaf hydrangea ‘Snowflake’ – Hydrangea quercifolia ‘Snowflake’

Oakleaf hydrangea 'Snowflake' IMG_8306Common Name: Oakleaf hydrangea ‘Snowflake’

Botanical Name: Hydrangea quercifolia ‘Snowflake’

Color: Summer green leaves that give way to a rich burgundy fall color. Showy creamy white flower heads that fade to a dusty rose.

Blooming Period:  Summer

Type:  Shrub

 

Size: Fast growing to 4 to 6 feet high and equally as wide.

Soil: Rich, medium moisture, well-drained soil.

Exposure: Part Shade

When to Plant:  Spring or fall

How to Plant:   Plant as an individual specimen to appreciate the unique foilage color and texture. ‘Snowflake’ can also be planted as a hedgerow and sheared for a dramatic effect.

Watering:   Water regularly during the growing season until established.

When to Prune:   Prune after flowering, however, little pruning is necessary

Cold Hardiness Zone: 5 to 9

Brief:  Oakleaf hydrangea ‘Snowflake’ has unique lobed leaves, with rich fall color. A native to the forests from Georgia south to Florida and west to Mississippi. This selections was discovered in 1969 by Eddie Aldridge and his father. I grow it in my Raleigh garden Helen’s Haven. It’s a great for gardening and landscaping in North Carolin, and is readily available in most local nurseries.

For more information on Oakleaf hydrangeas, here is a nice share from Mark Weathington, Assistant Director and Curator of Collections at the JC Raulston Arboretum.

Native to the southeastern United States, and hardy in U.S. Department of Agriculture hardiness zones 5 through 9, oakleaf hydrangea adapts better to different climates than the recognizable bigleaf hydrangea with mophead blooms. Sara Malone, Sonoma County master gardener, notes that oakleaf hydrangea thrives in Mediterranean climates, such as those in California. Malone reports that this plant is the only hydrangea on the list of “Top Plants for Sonoma County.” Its superior disease resistance makes this shrub a low-maintenance choice for beginning gardeners. Tolerant of varying soil types, oakleaf hydrangea performs well as an understory shrub, where it receives dappled sunlight under the canopy

Hydrangea quercifolia

Hydrangeas are mainstays in gardens throughout much of the United States. Their cheery flowers and shade tolerance make them invaluable additions to the landscape. Although only a few species are well represented in most western landscapes, the genus ranges from small shrubs to plants of almost tree-like proportions and scrambling vines. In mild climates, some species are evergreen while others are just barely woody plants at all and are almost closer to herbaceous perennials.

When most people think of hydrangeas though, they invariably picture the Asian species and our own natives often receive short shrift. Hydrangea species can be found in high numbers in Asia but are also represented in North, Central, and South America as well. On the east coast of the United States both Hydrangea arborescens and H. quercifolia are found.

Hydrangea quercifolia (hydrangea from the Greek for water jar in reference to the fruit shape and quercifolia from the genus name Quercus or oak and folia for leaf in reference to the oak-like leaf shape) or oakleaf hydrangea grows naturally from North Carolina and Tennessee south to Florida and west to Louisiana. It grows as an understory plant often along the edges of woodlands and streams. It makes a relatively large shrub in the wild and can often grow to 10′. There is a great deal of diversity among plants growing in the woods and many have been selected for different traits from size to flower length to fall color, and other characteristics.

Oakleaf hydrangea is a fairly coarse shrub which can make it difficult to fit into smaller landscapes. It bears large leaves with deep lobes much like a red oak. Leaf color ranges from glossy, deep green to matte green and often turns to spectacular burgundy and red in the fall. The stout stems have orange exfoliating bark and the winter appearance can be quite attractive after the leaves have dropped. The flowers are held in late spring on erect to nodding panicles which can be as long as 14″ on some selections. The white, sterile florets cover the small, fertile flowers to a great degree and while starting creamy white turn to pinkish-rose then tan and are persistent on the plant.

Massing oakleaf hydrangea is a particularly effective way to use them in a landscape where there is room. They can also be used as part of shrub borders and as specimens in woodland gardens. Oakleaf hydrangeas are tough performers in the landscape with few insect or disease problems. They are happiest in part shade with a moist root zone but will tolerate considerable sun and dry soil once they are well established although they will often look wilted by mid-day in sunny, dry areas. Never fear, they will generally perk back up by the next morning.

While the species is a very nice plant, the selections of H. quercifolia are typically much superior. Some of our favorite plants currently growing at the JCRA include the following:

‘Alice’ – This is a large growing plant with huge nodding panicles of flowers and large individual florets and excellent fall color. Introduced by Michael Dirr from the UGA campus.

‘Alison’ – Another Michael Dirr introduction from the UGA campus, this cultivar grows almost to the same size as ‘Alice’ with slightly smaller panicles that are held upright.

‘Flemygea’ (Snow Queen™) – This is a somewhat compact shrub from Princeton Nurseries to about 6′ with very large, dense flower panicles held very upright. This form supposedly holds up very well in more sun and is very cold tolerant, growing well into zone 5 once established.

‘Little Honey’ – Perhaps one of the most distinct cultivars, ‘Little Honey’ emerges with bright gold foliage that softens throughout the summer on a compact plant to about 5′ tall. The color is best in dappled shade and can burn in dry, sunny spots. Flowers are relatively small but become somewhat lost in the bright foliage anyway. Small plants may need two to three years before they really start growing well but are worth the wait.

A few newer selections which look very promising but that we have not grown for long enough to truly evaluate include:

‘Ice Crystal’ – This new selection is notable for its compact size with upright cones of white flowers. The jury is still out on whether this will be a big departure from the tried and true ‘Pee Wee’.

‘Munchkin’ – This selection from the USDA breeding program of Sandra Reed is a true dwarf with leaves one third the size of typical H. quercifolia on upright stems with short internodes. The flower panicles are held just above the foliage in 6” panicles.

‘Ruby Slippers’ – Another compact form from Sandra Reed’s breeding program, this plant has much longer flower panicles that emerge white but quickly turn to pink and then deep rose as they mature.

Words by:  Helen Yoest

Sponsored by the North Carolina Nursery and Landscape Association

 

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Wordless Wednesday – Miss Huff and a tiger swallowtail

Miss Huff

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Uh oh…Where’d all the impatiens go?


d do all the impatiens go?

You may have seen a new sign at your local nursery in North Carolina: Uh oh…Where’d all the Impatiens go?

There is a new mildew in town.

Over the last couple of years, impatiens downy mildew (Plasmopara obducens) has shown up in North Carolina gardens. Gardeners along the East Coast are beginning to experience what parts of Europe know all too well.

Impatiens downy mildew is harming one of the most beloved and reliable annuals in North Carolina, impatiens downy mildew is affecting all varieties of Impatiens walleriana, and a few native species of wild impatiens.

Weather affects outbreaks, and impatiens downy mildew likes our landscaping in North Carolina. Our warm temperatures and balmy nights make for prime conditions for the mildew to spread. There have been reports of entire beds dying in a week.

The good news is this brings opportunity for gardeners to branch out, and try some other shade-loving plants to replace your once tried and true.

Caladium Florida Elise TERRA CEIA FARMS

 

The colorful foliage of caladiums and coleus will give you the same kind of impact as masses of impatiens. Or planting Dragon Wing Begonia, Lamium maculatum ‘Orchid Frost’, or Brunnera macrophylla will give you foliage and a flower fix.

If you’ve already bedded out your impatiens, here what to look for: if the edges of the leaves are curled downward, take a peak. If the foliage is pale green or yellow, turn over the leaf to see if there is a whitish coating on the underside of the leaves.

If you have impatiens downy mildew, remove the affected plants before it spreads to the rest of them, and then hope for the best. There really isn’t much more you can do.

Here is more information from giving us an update on the state of the downy mildew disease.

From Ball Seed:

What is happening to impatiens? Impatiens downy mildew is a disease that affects all varieties of Impatiens walleriana. This includes common bedding impatiens, double impatiens and hybrid impatiens. Infected plants drop their flowers and leaves, resulting in bare, leafless stems that eventually collapse. The telltale sign of this disease is a white, velvety covering on the leaf undersides.

Are any other bedding plants affected by Impatiens downy mildew? While other bedding plants may be susceptible to downy mildew diseases, it’s important for you to know that the downy mildew affecting impatiens only infects Impatiens walleriana and a few native species of wild impatiens.

Will Impatiens downy mildew survive from year to year? There is some evidence that the pathogen that causes Impatiens downy mildew may survive in garden beds from year to year, so impatiens planted into beds with a history of this disease may be at a higher risk for infection. However, impatiens may become infected by windblown spores even if planted into garden beds with no history of this disease.

What should I do if I find plants infected with Impatiens downy mildew in my garden beds? If you spotted the white, velvety coating of spores on the leaf undersides  in your garden beds or outdoor containers, remove infected plants and any fallen leaf debris should be removed promptly, preferably well before the plants collapse. Seal in a bag, and discard bagged plants with regular waste. DO NOT COMPOST.

We want to know: what shade plants are you gardening with?

Words by:  Helen Yoest

Sponsored by the North Carolina Nursery and Landscape Association

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Buxus sempervirens ‘Unraveled’, weeping boxwood

Buxus sempervirens UnraveledCommon Name: Weeping boxwood

Botanical Name: Buxus sempervirens ‘Unraveled’

Color: Dark green

Type: Specimen, weeping, evergreen

Size: 4-foot tall by 7-foot wide

Soil: Well-drained

Exposure: Sun to shade

When to Plant: Spring or fall

How to Plant: Plant with root-ball at or above ground level in a hole 2 times the diameter.

Watering: Drought tolerant after established

When to Prune: Best not pruned to maintain the weeping form

Use: A great specimen plant for gardening and landscaping in North Carolina

Brief:  Shared from Mark Weathington, Assistant Director and Curator of Collections at the JC Raulston Arboretum.

Buxus sempervirens ‘Unraveled’

Boxwood has long been a mainstay of the landscape from the great gardens of Europe to the foundation plantings in neighborhoods across much of the United States. The genus is much more widespread than is generally known with about 75 to 105 species depending on your taxonomist of choice. The species are mostly tropical with concentrations in three main spots—across western and southern Europe to southern and Eastern Asia, Madagascar and Africa, and Mexico to the northern parts of South America. All species are evergreen shrubs and trees.

Almost all boxwoods in cultivation in the temperate zone are from the European and some Asian species, with the vast majority of landscape plants being selections of Buxus sempervirens. This species enjoys a relatively wide natural range from southwestern and west central Europe to west Asia and around the Mediterranean including northwest Africa. Common boxwood, as it is known, makes a multi-stemmed evergreen shrub or tree which can grow to over 25′ tall in the wild if left unpruned. The small leaves give boxwood a fine texture and the wood is extremely dense and durable and so has been used for musical instruments, small boxes, and for woodcut printing. The wood is actually so dense that it is one of the few types which will sink in water.

Boxwoods are used often for their formality in symmetrical foundation plantings and as formal hedges and parterres. The selection ‘Unraveled’ from the plantsmen at Yucca Do Nursery in Texas takes an abrupt departure from its buttoned-down relatives. Instead of forming an upright oval, it arches and cascades down for an elegant but very different effect. Unlike the old selections of weeping or pendulous boxwoods which were more irregular with drooping tips, ‘Unraveled’ is a true weeping plant.

Specimens of the lovely B. sempervirens ‘Unraveled’ can be staked up with a central leader and allowed to form a small, weeping tree or allowed to grow as they will forming a spreading shrub 4′ tall by about 7′ wide. The plant makes an outstanding four season specimen flanking a doorway or growing in a decorative pot but can also be used in mass on a dry hillside or cascading over a wall. It can also be used much like a traditional boxwood but will give a softer, less formal appearance which fits in well with modern landscapes.

Boxwoods are often placed in full sun situations but are actually quite happy growing in shade, even in hard-to-landscape dry shady spots. While ‘Unraveled’ will tolerate heavy shearing, it is best to only trim out errant branches and to prune to enhance the graceful character of the plant. Keep new plants watered to get them established but after the first couple of years, boxwoods will tolerate significant drought especially in some shade. ‘Unraveled’ has proven to be relatively pest and disease resistant and should be a long-lived, all-season specimen in the garden.

‘Unraveled’ is the newest addition to the JCRA’s and Johnston County Nursery Marketing Association’s Choice Plants marketing program. It’s available in limited supply this spring at some local garden centers. Be sure to check your local nurseries in North Carolina.

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Tarheel Gardening — Wordless Wednesda

Peony Rene Hortens

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2013 Showstopper Plants–Hydrangea macrophylla ‘Glowing Embers’

The North Carolina Nursery & Landscape Association (NCNLA) and North Carolina Cooperative Extension are pleased to announce our sixth year of Showstopper Plants.

Nominated by North Carolina nurserymen and selected by North Carolina Cooperative Extension horticulture experts, the 2013 Showstopper Plants are must have plants for any North Carolina landscaping. These featured plants are promising new cultivars or iron-clad plants that will thrive across the region. They are featured in Extension Gardener Learning Centers at home and garden shows throughout North Carolina.

Look for Hydrangea macrophylla ‘Glowing Embers’  in area North Carolina nurseries.

2013 showstopper plants Glowing Embers

 

What deciduous shrub makes a dazzling flower display for gardeners across the South? Why, it is ‘Glowing Embers’ Hydrangea. Abundant 8-inch flowerheads start out white colored, then turn to pink and eventually fade to a reddish-pink color.

Grow this garden plant in moist, well drained soil with ample amounts of organic matter. Glowing Embers,’ like most Mophead Hydrangeas, is sensitive to drought-like conditions and will be the first plant in the landscape to wilt when dry.

These Hydrangeas will grow in full sun but they grow best in partial shade. To insure the clearest pink flower coloration, add lime to the planting soil to help achieve a soil pH between 6 and 6.5. Tried and true in all of North Carolina, this shrub should prove to be another Showstopper!

Hardiness Zones: 6 to 9

 

Words by:  Helen Yoest

Sponsored by the North Carolina Nursery and Landscape Association

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2013 Showstopper Plants–Vitex agnus-castus ‘Shoal Creek’, Chastetree

The North Carolina Nursery & Landscape Association (NCNLA) and North Carolina Cooperative Extension are pleased to announce our sixth year of Showstopper Plants.

Nominated by North Carolina nurserymen and selected by North Carolina Cooperative Extension horticulture experts, the 2013 Showstopper Plants are must have plants for any North Carolina landscaping. These featured plants are promising new cultivars or iron-clad plants that will thrive across the region. They are featured in Extension Gardener Learning Centers at home and garden shows throughout North Carolina.

Look for Vitex agnus-castus ‘Shoal Creek’ also know as the Chastetree in area North Carolina nurseries.

 

2013 showstopper plants

If you are looking for a plant that doesn’t need any tender loving care, you won’t find a better choice than ‘Shoal Creek’ Chastetree.

Native to southern Europe and western Asia, Chastetree – or Vitex – grows into a multi-trunked large shrub ranging in height from 10 to 15 feet with a broad, spreading growth habit. Unlike the typical species, ‘Shoal Creek’ is an improved cultivar that possesses larger flower spikes of violet-blue flowers. ‘Shoal Creek’ Chastetree thrives in full sunlight and will tolerate most soil conditions as long as the soil is well drained. This plant selection is exceptionally more vigorous in growth than other varieties of Vitex.

Once this shrub becomes established it is very low-maintenance and extremely drought tolerant. In addition to its attractive violet-blue flowers, ‘Shoal Creek’ has interesting star-shaped, aromatic foliage that is grayish green on top with gray underneath. ‘Shoal Creek’ Vitex flowers attract both hummingbirds and butterflies, giving this Showstopper Plant an added bonus.

Hardiness Zones: 6 to 9

Words by:  Helen Yoest

Sponsored by the North Carolina Nursery and Landscape Association

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2013 Showstopper plants–Hibiscus ‘Fireball’

The North Carolina Nursery & Landscape Association (NCNLA) and North Carolina Cooperative Extension are pleased to announce our sixth year of Showstopper Plants.

Nominated by North Carolina nurserymen and selected by North Carolina Cooperative Extension horticulture experts, the 2013 Showstopper Plants are must have plants for any North Carolina landscaping. These featured plants are promising new cultivars or iron-clad plants that will thrive across the region. They are featured in Extension Gardener Learning Centers at home and garden shows throughout North Carolina.

Look for Hibiscus ‘Fireball’ in area North Carolina nurseries.

2013 showstopper plants flyerWhat has showy 10-inch red flowers from June through August? Why, it is the ‘Fireball’ Hardy Hibiscus and it has dazzled gardeners since its introduction in 2001. An attractive plant, ‘Fireball’ reaches a mature height of four feet.

Special to this plant is its ability to thrive in heat and humidity. Grow this tough perennial in full sun with evenly moist soil. In addition to its heat tolerance this perennial hibiscus is cold hardy from Zone 5 to Zone 9. In other words, ‘Fireball’ can be grown anywhere in North Carolina. ‘Fireball’s’ combination of impressive red flowers plus attractive, deeply cut green foliage with distinctive purple colored veins gives this plant charm for any sunny garden. Keep the soil from drying out and you’ll soon learn why this plant is a true showstopper!

Hardiness Zones: 5 to 9

Words by:  Helen Yoest

Sponsored by the North Carolina Nursery and Landscape Association

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