Scott Arboretum Curator Andrew Bunting cautions, “Eye-catching flowers can pull us in as if we were another pollinator, but we don’t want to limit our garden shopping to just buying at the big bloom time for a particular plant. Sure, a flowering plant makes an appealing nursery display, but purchasing plants only when they are in bloom is not a good strategy. You can, however, think ahead. Look at typical bloom times for your region, and easily chart out your selections with the aim of having a good seasonal flow of flowers.”

We asked Andrew to fill in a calendar with monthly examples of signature flowering shrubs. Here are Andrew’s picks for a “book-of-hours” monthly approach to illuminating your garden:

The silky white buds of Edgeworthia chrysantha open to a mass of tubular yellow fragrant flower. photo credit: R. Maurer

March Edgeworthia chrysantha – This is my favorite shrub for early spring flowering.  In late March, the silky white buds will open revealing masses of tubular yellow fragrant flowers.

April Fothergilla gardenii ‘Suzanne’ – ‘Suzanne’ is a diminutive selection of the fothergilla.  Before the leaves emerge, this shrub is adorned with fragrant, white bottlebrush-like flowers.

May Calycanthus x raulstonii ‘Hartlage Wine’ – ‘Hartlage Wine’ is one of the most exciting shrubs for spring flowers.  As the leaves are emerging, this Calycanthus is covered in large open-faced maroon flowers.

June Hydrangea paniculata Little Lime^TM – This is the dwarf version of H. ‘Limelight’, reaching only five feet tall at maturity. In June, cones of lime green flowers will emerge, turning white for the remainder of the summer.

Emmenopterys henryi is a great tree for a show stopping display in July. photo credit: D. Mattis

July Emmenopterys henryi – Emmenopterys is an exciting tree for its July flowers.  The large white bracts look as if they are hovering above the foliage.

August Lagerstroemia indica [Burgundy Cotton®]=’Whit VI’ – The crepe myrtles are a quintessential summer flowering tree.  This new selection contrasts beautifully its purple-black foliage with white flowers.

Disanthus cercidifolius' heart-shaped leaves backlit by the setting sun. photo credit: D. Mattis

Fall Color Disanthus cercidifolius – Many shrubs have outstanding fall color.  Disanthus has spectacular fall color.  Depending on the siting, the heart-shaped leaves can vary from fire engine-red to reddish purple.

Late Fall Ilex verticillata ‘Maryland Beauty’ – ‘Maryland Beauty’ is one of the finest clones of winterberry hollies.  From September to March the branches are heavily laden with cherry–red berries.

The attractive bark of Acer triflorum provides winter interest in your garden. photo credit: R. Maurer

Winter Our gardens do not end with a killing frost.  There are many plants that continue to provide interest on through the winter, including those with attractive bark, like Acer triflorum.  This small maple has a depth of orange-brown colors in its flaking bark and makes a great specimen tree.

Crytomeria japonica 'Yoshino' attractive pyramidal shape looks lovely with this light dusting of snow. photo credit: R. Robert

Of course, conifers stand out in winter, and Cryptomeria japonica ‘Yoshino’ is a great choice. This cultivar of Japanese cedar holds its color well in winter, has a strong pyramidal shape, and sheds snow well. It grows tall and fast in the sun, but will also perform in shade, just growing more slowly.

The eye-catching flower display of Hamamelis x intermedia 'Jelena' adds to your winter garden. photo credit: R. Manduca

However, our discussionis about eye-catching flower displays, and there are plants to brighten up the dead of winter with blooms—witchhazels, in particular. Hamamelis x intermedia ‘Jelena’ is a great choice. It has a copper-colored flower, rewarding close inspection because it’s also fragrant.  ‘Jelena’ generally sheds last-season’s leaves, so those blooms are not obscured, which happens with some witchhazels.

You can get full descriptive and cultural information on the plants Andrew mentioned from the Plant Sale Handbook. All these plants will be available for sale at the 2011 Scott Associates Plant Sale.

Another good resource to help you plot peak bloom times is this table at the Missouri Botanical Garden website. The calendar charts blooming for their area of the Midwest, but their USDA hardiness is comparable to our region.

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Ted Patterson, from Wayne, PA, retired from public relations work with the U.S. Dept. of Agriculture, is a co-chair of the woody plant section at the Scott Associates Plant Sale.

With patience, the swamp white oaks of Magill Walk have matured into a striking alley. photo credit: R. Maurer

“Some components of a garden design offer an instant hit or they hit the ground running,” says Scott Arboretum Curator Andrew Bunting. “But there are plants where it takes a bit of patience for them to fully realize their true attributes. And that is really the ultimate gratification for a gardener—to nurture a plant through a number of seasons and see its development unfold.”

With that philosophy in mind, and in keeping with our 40th anniversary theme, Andrew identified some examples of plants that reward patience:

Wonderful fall color of Acer triflorum. photo credit: M. Blandford

Acer triflorum will develop into a beautiful small specimen tree with tawny peeling bark and wonderful sugar maple-like fall color.

Camellia japonica ‘Korean Fire’ is a perfectly hardy selection for the Delaware Valley.  Over time it will reach 15 feet tall and will be adorned in early spring with deep red flowers.

Cedrus deodora 'Silver Mist' has lovely silver-green foliage. photo credit: J. Coceano

Cedrus deodara ‘Silver Mist’ will develop into a majestic specimen conifer with silver-green foliage and arching branches.

Cercidphyllum japonicum ‘Morikawa Weeping’, a weeping form of katsura, becomes more and more elegant with time.  The long weeping branches create a stunning cascading habit with remarkable golden fall color.

Chionanthus retusus ‘China Snow’, like all Chinese fringetrees, becomes more and more spectacular with age.  At maturity it will reach 25 feet tall with an equal spread.  In May it will be adorned with feathery white flowers.

The distinquishing white bracts of Davidia involucrata. photo credit: R. Maurer

Davidia involucrata ‘Sonoma’ is a relatively new selection of the dove tree, which has larger than normal white bracts.  Davidia is unequaled for its significant flowers in the spring.

The white bracts of Emmenopterya henryi. photo credit: D. Mattis

Emmenopterys henryi remains one of the rarest trees in cultivation. This upright tree requires at least twenty years of growth before it comes into flower, but once this occurs you will be treated to stunningly large white bracts in July that look as if they are hovering over the branches.

Stunning fire-engine red fall color of Franklinia alatamaha. photo credit: R. Maurer

Franklinia alatamaha is a plant for all seasons.  In the summer, it is covered with large, white, camellia-like flowers; the fall color is a stunning fire-engine red; and the stems have interesting grey and white striations for winter interest.

Magnolia virginiana var. australis 'Henry Hicks' has intensely fragrant flowers. photo credit: ML Gessel

Magnolia virginiana var. australis ‘Henry Hicks’ was selected by Scott Arboretum’s own Dr. Wister because this sweetbay magnolia is nearly evergreen in the Philadelphia area.  Sporadically throughout the summer it has intensely fragrant flowers and is one of the few magnolias which will tolerate wet soils.

You can get full descriptive and cultural information on the plants Andrew mentioned—indeed on all selections, in advance—from the Plant Sale Handbook.

A final note on patience:

Biggest is not always best when it comes to purchasing plants. Large multi-gallon container plants or balled-and-burlapped plants do not necessarily succeed better than smaller container plants. All transplants take time to settle in and establish a good root system. A small container plant may have a quicker period of root adjustment, and after a few years of growth it may be equal in size to its multi-gallon cousin.

Plant experts helps shoppers at the Scott Associates Plant Sale choose the best plants for their garden. photo credit: J. Goren

Read about planting a tree on page 57 in the Plant Sale Handbook or discuss planting methods with a plant expert at the 2011 Scott Associates Plant Sale. We want your gardening patience to be rewarded.

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Ted Patterson, from Wayne, PA, retired from public relations work with the U.S. Dept. of Agriculture, is a co-chair of the woody plant section at the Scott Associates Plant Sale.

Renovation of the Cunningham House front entrance circle and walk is underway. Taking a cue from the construction, we took the opportunity to renovate the gravel path in the Scott Entrance Garden. The gravel path skirts under a fine specimen of Magnolia virginiana var. australis ‘Henry Hicks’, expands to highlight a clay urn, then exits along the sidewalk beside a grouping of Pinus strobus ‘Nana’.

Steel landscape edging. photo credit: J. Coceano

Over time soil from the planting beds migrated into the gravel. To remedy this, a steel landscape edging was installed. Readily available from home improvement stores, the edging is secured with metal stakes.

Matt Krapf, summer intern, spreads gravel. photo credit: J. Coceano

Next, gravel was spread. 3 tons of ½ inch granite gravel was obtained. About 2.5 tons was spread. The remainder is stored for touch ups and top dressing cacti and succulent containers. Andrew Bunting, curator, suggests an ideal gravel depth of 3-4 inches. Another consideration would be to lay down a weed mat under the gravel to suppress weeds and prevent the gravel from settling into the earth.

Completed renovation on the gravel path in Scott Entrance Garden. photo credit: R. Robert

Paths can vary in size, shape, and color. They can run in a simple, straight line, or can be elaborate and have a decorative, serpentine curvature that weaves and flows. Such paths are easy to install and can be accomplished during the course of a day or over a weekend.

Gravel can be used to create low traffic pathways and to top dress succulent containers. photo credit: R. Robert

Gravel is an economical choice averaging 25 to 50 cents per square foot and coming in a variety of colors. This is cheaper than flagstone, brick, or concrete. Gravel can get lodged in the bottom of shoes and be difficult to push or pull wheeled objects; therefore, gravel paths are ideal for low to moderate foot traffic.

Here is where our hardy installation crew got a workout hauling heavy buckets of rock to all corners of the roof.  Swarthmore College gardener Bill Costello made many trips up and down the roof’s access ladder helping to load the pallets in the parking lot down below and then unload them on the roof.

This larger stone is used in places where the plants have a harder time growing, for example under the edges of the pitched roof where the water drains.  It is also used along the edges of the roof to prevent material from being blown off in this windier zone.

The majority of the roof is covered with our final layer of material, the growing media. The essential attributes of green roof growing media are: it is lightweight and drains well.  It also must contain some compost to provide nutrients to the plants.  On the Wister Center roof, as on our previous green roofs, we used a growing media called rooflite that is blended in nearby Chester County and delivered to us in large sacks weighing hundreds of pounds. Two of these sacks were lifted by crane and suspended over the roof so that they could be slit open and pushed around to pour the material roughly where we wanted it. The media was then raked around the roof to an even 2-3” depth.

Two weeks later, when work schedules allowed and rain was in the forecast, the stars of the show, the plants, were put to work. We were able to dig several dozen clumps of various species of sedum from our David Kemp green roof as well as harvest a variety of sedum cuttings. This plant material was immediately carried up the ladder to the Wister Center roof and planted or, in the case of the cuttings, evenly strewn over the growing media and watered in.

Now it is up to the plants to do their job of establishing themselves and filling in the bare spaces to create the colorful mosaic of a vegetated roof. We continue to be awed and inspired, as well as educated, by these green roof installations on campus. In addition to the significant ecological services they provide, green roofs are ever-changing kaleidoscopes of life.

The Wister Center green roof has earned a special place in the hearts of arboretum staff because it is the first one we have installed (almost) all by ourselves. Previously the college has employed outside contractors to design and install our green roofs, and we gardeners have served as enthusiastic acolytes and willing apprentices, as well as loyal maintainers. This time, however, we came close to flying solo.

Our co-pilot was Peter Philippi the seasoned green roof guru who designed our Alice Paul and David Kemp roofs. Peter has direct experience with many vegetated roofs including a thirty-year-old green roof in Germany that is still going strong.

Most of our materials needed to come via pallets hooked to the end of the very long arm of a crane.  Local arborist Knight Brothers very generously donated the services of this crane and its operator.

On top of the roof’s waterproof membrane goes a thick blanket of recycled polyester fabric that both protects the waterproof membrane and holds on to moisture.

Next came a drainage layer: thin, stiff plastic sheets with drainage channels molded into them. This was a change from our earlier green roofs, which, for the drainage layer, had used an expanded shale product called Solite that was developed and generously donated by an alumnus of the college.

The plastic drainage sheets were used because, unlike our other roofs, the Wister Center has sections of pitched roof that drain onto the green roof.  We anticipate these pre-molded drainage channels will be more efficient in handling the increased volume and velocity of run-off from these pitched roofs.

On top of the drainage layer is a second, thinner blanket of recycled polyester, acting as a filter to keep particles of growing media from clogging the drainage layer and to retain moisture.

Stay tuned for Part II of the Green Roof installation: a glimpse at the installation of growing media and planting of sedums.

Tillandsia xerographica, Aechmea 'Patricia'

A vast selection of unusual, vibrant tropical plants will overflow from the Wister Center May 21-22 as the Arboretum hosts its first Unusual Annuals and Tropicals sale.  An array of bromeliads, elephant ears, succulents, ferns, vines, begonias, and cannas are just a few of the plants that will be available, providing a prime opportunity to add outstanding colors and textures to your home garden and summer containers.

One of the highlights of the sale is the selection of bromeliads, including Aechmea blanchetiana ‘Orangeade’, Aechmea lueddenmanniana ‘Mend’, and Aechmea penduliflora.  Aechmea blanchetiana grows in the wild in Brazil’s Atlantic forest ecosystem and prefers full sun and regular watering.  With potential to reach 3 feet tall and 3 feet wide, this showy tropical also attracts bees, butterflies, and birds.

Aechmea lueddenmanniana has gorgeous arching foliage with a stripe of pinkish-orange along the center of each leaf.  It produces a tall spike of lavender flowers which develop into white berries that can last through the summer season and gradually turn purple. This plant is hardy and also freely produces pups after flowering.

The sale will also feature more than a dozen species of Tillandsia, commonly known as air plants.  If you are seeking ideas for unique digressions from traditional summer planters, consider creating a grouping of epiphytic Tillandsia.  They can be mounted on wood, bark, cork, porous rock, in loose sand, or on any surface that retains moisture.  The long, slender foliage bursting from the center of these plants provides eye-catching forms.  They do well with moderate shade and are slow-growing which makes them easy to manage.

Tillandsia capitata

These hard-to-find tropicals create instant impact in containers and landscapes, adding exotic accent to your outdoor designs.  For a look at examples of how the Scott Arboretum uses tropicals in container arranging, check out the “Burle baskets” hanging in the Terry Shane Teaching Garden.  These large baskets contain a bountiful assortment of tropicals that flow 360 degrees around the basket.

The sale will be on Saturday, May 21 from 10:00-12:00 (Members only) and general admission from 12:00-3:00.  On Sunday we will be open from 10:00-2:00.  New members who join the Arboretum will be eligible for early shopping on Saturday and will receive a $10 voucher that can be used to purchase plants.

Neoregelia 'Fireball'

]]> http://blogs.scottarboretum.org/gardenseeds/2011/05/tropical-sale-preview/feed/ 0 http://blogs.scottarboretum.org/gardenseeds/2011/04/making-burle-baskets/ http://blogs.scottarboretum.org/gardenseeds/2011/04/making-burle-baskets/#comments Mon, 25 Apr 2011 15:28:13 +0000 Laura Stiebitz http://blogs.scottarboretum.org/gardenseeds/?p=2936

Looking for new ideas for summer containers?  In mid-May, the Arboretum will be putting out lush hanging baskets of tropicals.   Named “Burle basket” after the renowned Brazilian landscape architect Roberto Burle Marx, these baskets are a creative way to make an impressive, three-dimensional impact with tropical plants.

The base of the structure is a wire frame, in either a half sphere or conical shape.  The frame is then filled with sphagnum moss, which effectively retains the moisture for the plants.  Next, a good quality, moisture retaining soil is added.    When placing the plants, it is best to start at the bottom…

Looking for new ideas for summer containers?  In mid-May, the Arboretum will be putting out lush hanging baskets of tropicals.   Named “Burle basket” after the renowned Brazilian landscape architect Roberto Burle Marx, these baskets are a creative way to make an impressive, three-dimensional impact with tropical plants.

The base of the structure is a wire frame, in either a half sphere or conical shape.  The frame is then filled with sphagnum moss, which effectively retains the moisture for the plants.  Next, a good quality, moisture retaining soil is added.    When placing the plants, it is best to start at the bottom of the basket and work your way up towards the top.

There are limitless possibilities for arrangements.  We used different types of Begonias, Xanthosoma (elephant ears), Peperomia, ferns such as Nephrolepis exaltata and various kinds of bromeliads, which add accent color.  To maximize the beautiful cascading qualities of these tropical baskets, we recommend using trailing plants such as Cissus or Tradescantia.  One of my favorite ornamental plants, Cyperus alternifolia, is also great for adding height and texture.

The Unusual Tropicals plant sale May 21-22 will feature an array of bromeliads, elephant ears, succulents, ferns, vines, begonias, cannas, and other rare finds — an inspiring selection for creating your own bountiful Burle Basket.

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In recent years, the Dean Bond Rose Garden has been hit hard by rose rosette disease. This is a disease believed to be caused by a virus that has been spreading through much of the wild rose population of the United States for years. It is of great concern to the nursery industry and to many home gardeners because it is known to be lethal to the wild multiflora rose (Rosa multiflora) and it is potentially lethal to many ornamental rose species and cultivars. The disease is known to be spread only by a very small, wind-dispersed eriophyid mite, Phyllocoptes fructiphilus, or by grafting. We ended up with some very big vacancies in what used to be a robust display of roses. As we noticed the virus, we removed affected plants. This experience made us more aware of the hazards of spreading disease in a collection especially when it is a monoculture.

These major openings in the rose garden gave us an opportunity to replant with more disease-resistant and sustainable roses. The disease is not known to reside in soil, so it is fine to replant roses in the same place. There is no treatment for rose rosette disease. The major disease for which we use chemicals in the rose garden is black spot. Some rose species are naturally resistant to the disease, but the more “modern roses” such as hybrid teas or floribundas tend to need chemical intervention to keep them healthy.

Blackspot is caused by the fungus, Diplocarpon rosae, which overwinters on diseased rose canes and fallen infested leaves. Spores produced on fallen leaves are spread via rain or by water splashed to newly emerged leaves and stem tissue in the spring. Under ideal conditions of leaf wetness, humidity, and temperature the spores can germinate and infect in 1 day, cause symptoms in 4 to 5 days, and produce new spores that can infect additional leaves, flowers, and canes within 10 to 11 days. Spores are easily moved by air currents. Bill Costello, our Integrated Pest Management coordinator, rotates the spraying of three different fungicides on a 10 to 14 day basis every season beginning as soon as the roses leaf out until the end of the season. We chose rose cultivars that showed promise of black spot resistance and encouraged increased air circulation by planting roses less densely than they were previously planted.

Since most of the roses that had been affected were modern re-bloomers or shrub roses, we took guidance from the ongoing evaluations at the Peggy Duke Rose Garden at the New York Botanic Garden where they have been replanting their rose garden with disease resistant repeat-blooming modern roses. They share our northeast climate (http://www.nybg.org/gardens/rose-garden-home.php). They have done an excellent job of documenting the replanting and evaluation of roses for disease resistance. We also took recommendations from rose growers and other trial programs. There are several notable programs promoting roses that have been selected and tested for increased disease resistance. A few of the programs that we looked at when deciding what roses to plant are listed below.

Texas Pioneer Roses were developed at Antique Rose Emporium. These are the result of breeding the showiest and toughest antique roses and selecting carefree, repeat-blooming offspring. Disease resistance, thornlessness, and fragrance have also been valued in this breeding program.

Kordes Roses were developed through the breeding program of Germany’s preeminent nursery, W. Kordes Söhne. These are robust, extremely floriferous varieties that have typically won prestigious awards for disease resistance in trials in Europe. With extraordinarily healthy foliage, these roses are stand-outs among “no-spray” varieties. We chose many Kordes selections for replanting the Dean Bond Rose Garden.

EarthKind Roses are the result of testing at Texas A&M University that is ongoing. The tests are designed to identify rose varieties that can be grown well with no or minimal care and are highly disease-resistant and practically immune to blackspot. Stephen George, Ph.D. currently heads the program begun by Robert Basye, Ph.D.

Rose Cultivar Name             Type of Rose                        Flower Traits                                Introduced by:

To replace the lawn in Cosby Courtyard, the irrigation system was removed and the area excavated.  Over the compacted subgrade, four inches of drainage gravel were added.  Next, the dry “Stabilized Grey Mountain Gravel” was put down.  After being thoroughly wetted, the product was compacted with a roller. Once dry, the product was ready for use.

This renovation project provided an opportunity for the Arboretum consolidate the artful display of container plantings. The big copper urn that had been tucked into the black bamboo, Phyllostachys nigra, was moved out onto the gravel as were several other containers. This allowed for a spectacular display of late summer plant combinations and a prominent area for the wonderful winter containers.  In addition to providing beauty and interest, the containers also help direct foot traffic through the area.

Although not a consideration for the renovation in Cosby, using “Stabilized Grey Mountain Gravel” could provide for up to five Leadership in Energy and Environmental Design (LEED) points in the categories of stormwater management (2 points), reduction of heat island effect (2 points), and use of local/regional material (1 point).

“Stabilized Grey Mountain Gravel” is also being installed at the south entrance slope to the Scott Amphitheater as part of a project to improve accessibility into the Amphitheater.

As Sam Keitch enjoys the last weeks of his curatorial internship, he was called upon to create the latest addition to the Arboretum’s ephemeral art using dead or dying trees. Many may remember the “blue tree” created by another curatorial intern, Todd Rounsiville, out of a Maackia chinensis suffocated by construction compaction. Marty Long carved the intriguing Bender oak sculpture out of a dying Quercus x benderi. Fashioned in the same vicinity as Sam’s masterpiece, artist Patrick Dougherty shaped the ephemeral art sculpture “Abracadabra” on a dying Tilia ameicana.

Sam Keitch, curatorial intern, painting the lower portion of the bur oak with the help of Irene Palmer, summer intern. photo credit.: R. Robert

Sam’s recent creation is of a dying Quercus macrocarpa. This 10-year-old bur oak suffers from physiological problems with the roots. While we are not sure of the exact cause, it may include reasons like being planted too deeply or girdling of the roots. No matter the cause, as with other similar ephemeral art projects, the Arboretum saw this as an opportunity to draw attention to the loss of the tree and to amuse, excite, and create wonder in the community.

Sam Keitch creates his masterpiece while an Arboretum visitor watches his progress. photo credit. R. Robert

Titled “In the Shadow of Abracadabra,” Sam has sprayed this 30-foot tree “geranium red” using a power sprayer. It took him about two and half days to create this new icon in the landscape. See photos detailing his progress on our facebook page. Located in front of Trotter Hall, this red tree mimics colors in the Dean Bond Rose Garden and draws the eye of visitors to Parrish Hall, McCabe Library, and Trotter Hall. Because this work is located in the same vicinity of the Patrick Dougherty sculpture, “Abracadabra”, the title of “In the Shadow of Abracadabra” seemed appropriate.

Sam Keitch painting the upper portion of the bur oak. photo credit: A. Bunting

In our past experience, painted trees last from two to three years. This will give us all plenty of time to enjoy the piece in all the seasons. Stop by the Arboretum to see Sam’s last intern project and experience a red tree and red roses.