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

Pulmonarias: Wonderful In The Shade Garden

Posted by Hugh on March 6th, 2011

Although my multi-year addiction for hostas has never waned, I remain equally passionate about the lungworts (Pulmonaria spp.). Lungwort is also called Bethlehem sage and Jerusalem sage. Their uniquely splotched or variegated foliage wakes up a dark patch in any shade garden.

Lungworts are planted as ground covers and for color accents. In early spring (March), lungworts send up small lovely bouquets of small tubular flowers. Flower colors, depending on variety, range from white, lilac, pink and blue.

Lungworts are vigorous and long lived. Several are semi-evergreen in garden zone 6 and deciduous in zone 5. Their culture is almost identical to hosta. Grow them in compost-rich soil and keep plants mulched and moist in the summer months. Lungworts benefit from division every 4-5 years.

Pest problems are rare, although some cultivars may be susceptible to mildew. The species P. longifolia and hybrids thereof, with long narrow or lance-shaped leaves, are most adaptable to gardens in the Southern Appalachian region (USDA zones 6 and 7). They’re more resistant to mildew diseases and high temperature dieback. Occasionally, snails and slugs are problem pests.

Suggested companion plants include ferns, small leaved hostas, bluebells (Mertensia), coralbells (Heuchera spp.), foamflowers (Tiarella spp.), dwarf variegated Solomon seal (Polygonatum spp.), and lenten rose (Helleborus spp.).

Prune Some Hydrangeas Now

Posted by Hugh on March 3rd, 2011

Hydrangea paniculata 'Limelight' in July

PeeGee or panicled hydrangea (Hydrangea paniculata) and our native Smooth hydrangea (Hydrangea arborescens) are pruned now in late winter thru early spring. Why? – because these hydrangeas bloom on new or current season’s wood.

Over the years these two hydrangea species grow to enormous sizes. When they overwhelm their garden space, severely cut them back to within 6 -12 inches from the ground in late winter or early spring. Next, thin out the number of shoots (canes), leaving several of pencil size thickness. In the spring each cane will grow out new shoots which bloom this summer.

Severe cutting back is called renewal pruning. Timing will vary with the species of hydrangeas planted in your garden. After pruning apply a slow release fertilizer especially formulated for flowering shrubs. Follow the package directions. Apply a good organic mulch to a 2 – 3 inch depth around each hydrangea to conserve soil moisture this summer.

Oakleaf (H. quercifolia) and bigleaf (H. macrophylla) hydrangeas may also be pruned now, but flower numbers in spring and summer may be greatly reduced.

Winter Jasmine Rising

Posted by Hugh on March 1st, 2011

Retaining wall of winter jasmine

Is the worst of winter behind us? Winter jasmine (Jasminum nudiflorum) is often confused with forsythia shrubs which bloom 3-4 weeks later in the spring. This hardy winter blooming vine from China frequently blooms in late February and March when daytime temperatures climb into the mid-50s for a week or more. Evening chilling temps down into the low 20’s don’t seem to injure the flowers.

This vine thrives in many parts of the mid-Atlantic and southeastern U.S. (USDA hardiness zones 6 -8) in full sun to partial shade. Its dark green tri-foliate leaves are semi-evergreen in zone 6. New foliage emerges in April after flowering has ended.

Hundreds of bright yellow 1 ½ inch tubular flowers are lightly fragrant, originating along a thick network of green stems. Winter jasmine is a very aggressive grower and is often utilized for soil retention on steep banks or to cover over an unsightly retaining wall or fence. Some gardeners grow it as a low 3-4 foot tall shrubby mound, 4-5-6 feet wide.

Winter jasmine grows in almost any soil, and demonstrates good drought tolerance once established after two years. Every 3 or 4 years rejuvenate winter jasmine by cutting back vines severely immediately after flowering.

Prune as needed in early spring just after flowering has finished. If planting starts to look scraggly, cut back hard to 12-18 inches and feed generously with 10-10-10 or equivalent fertilizer.

‘Kintoki’ Japanese Cornel Is Perfect Fit for Small Urban Gardens

Posted by Hugh on February 27th, 2011

: ‘Kintoki’ summer foliage

It’s a dogwood and comes close to being a plant that offers four seasons of landsape beauty. Kintoki Japanese cornel (Cornus officinalis ‘Kintoki’) is a special semi-dwarf 10-12 foot tall dogwood which fits into most small gardens. Kintoki’s bright yellow flowers open in early March in the Southern Appalachian region (USDA zones 6 and 7).

Bloom season is almost 4- weeks long, and begins 3 – 4 weeks ahead of forsythia. A frigid winter’s evening does not hurt the blooms. The foliage exhibits a dark green polished finish and purplish fall foliage color does not occur is not until late November.

Japanese cornel grows in most soils as long as the drainage is good. Plant in a full sun to partial shade location where it’s easily visible from inside your home. When in bloom, March weather is often wild and changeable and gardeners can remain warmly huddled indoors.

In the fall attractive Kintoki’s multi-colored bark and bright edible drupe fruits offer autumn thru winter interest for humans, birds and other wildlife. Over the next 2-3 years, availability of Kintoki is likely to be limited to specialty nurseries selling in the internet marketplace.

‘Sunsphere’ Japanese Cornel

Posted by Hugh on February 24th, 2011

'Sunsphere' Japanese Cornel

Japanese cornel (Cornus officinalis) is a tall shrub or small tree dogwood which matures to 20-25 feet in height and 15 feet in width. ‘Sunsphere’ Japanese cornel was discovered by Mike Stansberry, owner of Beaver Creek Nursery in Knoxville, TN.

Japanese cornel is the official start of spring in my garden, even though the calendar reads late February. This cultivar is a heavy bloomer, the bright yellow flowers about 7-10 days before other Japanese cornels. Flowers are rarely injured by low night temperatures still common across the Southern Appalachian region (USDA zones 6 and 7) in late February and March.

Japanese cornel grows in any average well-drained soil in full sun to partial shade. Spring-summer foliage is dark green, and autumn colors varing from light yellow to reddish purple before falling. As the grayish outer bark ages, it chips off in tiny strips, exposing the yellow-orange inner wood. In late summer the cherry red drupe fruits have colored up and are consumed by hungry birds.

Sunsphere is available thru internet purchase or stop by Beaver Creek Nursery in Knoxville, TN.

Next up: ‘Kintoki’ Japanese cornel features lovely summer-fall glossy foliage

Edgeworthia Deserves A Try

Posted by Hugh on February 21st, 2011

: Edgeworthia flowering in March garden

First, I must thank South Carolina nurseryman, Mr. Ted Stephens, who gifted me a Chinese paperbush (Edgeworthia chrysantha) nearly 6 years ago. Most plant authorities rate its winter hardiness to USDA zones 7 and 8. It struggled through its first winter and spring in my zone 6-b garden, but has never disappointed. A few gardeners living near me are also enjoying some success.

Paperbush is not difficult to grow and is fascinating to watch as cold temperatures moderate in early March. The uniquely nodding floral buds are clearly visible on branch tips in early fall. Fragrant flowers open in early March before the new spring foliage emerges. The tubular clusters of flowers are light yellow on the inside and white on the outside. After a number of years roots will sucker new plants, forming a small plant colony. If your plant reaches suckering stage, congratulations, it is happy in your garden.

Its greenish blue foliage is attractive over the 4-5 feet tall plants. Paperbush is a multi-stemmed shrub. The new growth is coated with fur-like reddish brown hairs. Paperbush belongs in a protected woodland environment under partial shade in the summer. Its unusual flowering and early season flowering entice plant collectors to give it a try.

Paperbush is definitely a collector’s plant and is available at e-commerce nurseries.

Revitalize Pansies Now

Posted by Hugh on February 18th, 2011

Across many areas of the Southern Appalachian region (USDA zones 6 and 7) snowfall has been plentiful this winter, but total rainfall is below normal. It takes 10 inches of snow to equal one inch of rainfall.

Fall planted pansies and violas are now both hungry and thirsty. Provide them with a shot of fertilizer and water. Winter feeding will not injure these hardy plants.

Apply an agricultural grade of fertilizer such as 19-19-19 or equivalent. Do not use a slow release granular product this time of year as the fertilizer prills do not release their nutrient charge in cold soils. Any water soluble fertilizer, including Miracle Gro® or Jacks® brands, are also good choices for feeding pansies and violas. Follow package directions.

Irrigate thoroughly after feeding to wash the nutrients into the soil as well as to re-hydrate plants. Watering also prevents the fertilizer salts from burning the plant foliage.

Withis a few days your listless pansies should perk up during this warm weather spell which we are currently enjoying.

Opening Show in February- The Witchhazels

Posted by Hugh on February 15th, 2011

Chinese witchhazel (Hamamelis)

First, not to confuse you, our North American native witchhazel (Hamamelis virginiana) blooms in the fall. Our native vernal witchhazel (H. vernalis) has been flowering for the past few weeks.

In February, the showiest witchhazels are opening now – species from China, Korea and Japan. Two of the very best are a Chinese species/cultivar called H. mollis ‘Wisley Supreme’ and a hybrid form called H. x intermedia ‘Westerstede’. Both are hardy in the Southern Appalachian region (USDA zones 6 and 7).

Let’s begin with Wisley Supreme. This vigorous shrub grows to 8 – 12 feet in height and 10 – 12 feet in width. A young shrub branches upright and with age takes on a spreading habit. Its pale yellow strap-like flowers are long lasting and sweetly scented. Spring-summer oval leaves exhibit a bluish green cast, turning buttery yellow in the fall.

Westerstede is a hybrid witchhazel from Germany (Japanese (H. japonicum) and Chinese (H. mollis). Westerstede bears light yellow 1- inch long ribbon-like flowers which are fragrant. Floral buds begin to open 1 – 2 weeks later than Wisley Supreme. The broad 5 – 6 inch circular green leaves turn buttery yellow in the fall.

While most hybrid witchhazels grow to tall 20 foot shrubs, the mature heights and widths of Westerstede and Wisley Supreme are similar. Westerstede summer foliage possesses better leaf spot resistant than the old-timey favorite ‘Arnold Promise’.

Witchhazels are easy to grow in an average well-drained moist garden soil. A slightly acidic pH soil is preferred. Annual spring pruning keep the vigorous witchhazels within their assigned garden spot.

Since most garden centers do not sell early blooming shrubs, witchhazels are easily purchased from the internet nursery market.

Crabapple Shopping List

Posted by Hugh on February 10th, 2011

‘Prairifire’ crabapple

For those of you tired of the monotony of Bradford pears, go shopping for ornamental crabapples (Malus spp.). Most crabapple cultivars mature into long-lived small flowering trees less than 20 feet in height at maturity. Most fit under utility lines.

Worldwide, there are over 400 cultivars of crabapples in nursery commerce. Most are susceptibility to one or more serious foliar diseases. These pathogens include fire blight, cedar apple rust, apple scab, powdery mildew and frog-eye. All 18 listed below are rated with good to excellent disease resistance.

Ornamental crabapple fruit add ornamental beauty from late summer through winter. Fruit size is small, less than 5/8 inches in diameter, and large flocks of small birds are attracted to your property. There is no mess on lawns, walkways or cars.

Here is your shopping list of 18 of the best.

Adams – 20 x 20ft. (magenta flowers & red fruit)

Adirondack – 18 x 10 ft. (white flowers & orange-red fruit)

Cardinal® – 16 x 22 ft. (pink-red flowers & red fruit)

Centurion® – 20 x 15 ft. (pink flowers & red fruit)

David – 12 x 12 ft. (white flowers & red fruit)

Donald Wyman – 20 x 20 ft. (white flowers & red fruit)

Doubloons – 18 x 16 ft. (double white flowers & yellow fruit

Firebird® – 8 x 10 ft. (magenta flowers & red fruit)

Louisa – weeping 10 x 12 ft. (pink flowers & yellow fruit)

Pink Princess™– 8 x 12 ft. (rose pink flowers & red fruit)

Prairifire – 20 x 20 ft. (red-purple flowers & dark red fruit)

Purple Prince® –20 x 20 ft. (rose red flowers & maroon fruit)

Royal Raindrops® – 20 x 15 ft. (pink red flowers & red fruit)

sargentii – short spreader 8 x 14 ft. (white flowers & red fruit)

sargentii ‘Tina’ – dwarf 5 x 6 ft. (white flowers & red fruit)

Sugartyme® – 18 x 15 ft. (white flowers & red fruit)

White Cascade® – weeping 15 x 15 ft. (white flowers & lime-yellow fruit)

zumi ‘Calocarpa’ – 20 x 24 ft. (white flowers & red fruit)

* Thanks to J. Frank Schmidt & Sons Co., Boring, OR for their cultivar height and width data and foliar disease ratings.

The Other Lenten Roses

Posted by Hugh on February 7th, 2011

Lovely cut foliage of Bearsclaw hellebore

In addition to the popular Oriental hellebore (H. x orientalis), four other species are hardy in the Southern Appalachian region (USDA hardiness zones 6 and 7). Christmas rose (H. niger) is the first lenten rose to bloom, often 4-6 weeks earlier if mild December weather permits. The 3 ½- inch flowers are large and showy, each borne singularly on 2 to 2 ½ foot tall stems.

Corsican hellebore (H. argutifolius) features large yellowish green flowers and glossy light green leathery foliage. Leaves are holly-like, with spiny deeply cut edges. Flower longevity lasts 10 or more weeks. The slightly nodding flower heads emerge from the crown to stand above the foliage. After the seeds ripen in mid-summer, stalks collapse to make room for new growth. Corsican hellebore may require some winter protection in coldest locales of the Southern Appalachian region.

Bearsfoot hellebore (H. foetidus) flaunts dark green, deeply dissected foliage. Each of the green blossoms is edged in purple and blooms at same time as H x orientalis. This species is best planted in a cool, shaded garden area as it is not heat tolerant.

Hellebore blooms make long lasting additions to any cut flower arrangement. To prevent the leaves, buds and flowers from wilting, re-cut each stem using a sharp knife or bypass pruners while holding the stalk submerged in water. This practice assists in continuous water uptake in the stem and improves flower longevity.