The NAPCC is part of the American Public Gardens Association (APGA).  The NAPCC is an advocate for raising plant curation, plant records, and collections management standards.  It is also a seal of approval for plant collections found in botanical gardens and arboreta that exhibit exemplary collections of plants  throughout North America.

James R. Frorer Holly Collection is located on a south facing slope along the Crum Creek. photo credit: D. Mattis

The Scott Arboretum holds three NAPCC collections including Ilex, hollies; Quercus, oaks; and Magnolia. Our first collection to get NAPCC status was the holly collection.  The lion’s share of this collection is found in the James R. Frorer Holly Collection on the south facing slopes along the Crum Creek. This collection was donated by Swarthmore College graduate, James R. Frorer in 1974 from his property in Wilmington, Delaware.  Today, the collection represents over 290 different kinds of hollies.

There are some great rest spots found among the blossoms of the Magnolia Collection. photo credit: J. Jin

Another significant collection with NAPCC status is our Magnolia Collection. Historically, the “collection” existed around Mertz Dormitory, Worth Health Center, and the Benjamin West House.  Over the last 15 years due to growth of the collection we have expanded out magnolia plantings to the West Garden, Tree Peony Garden, Sharples Dining Hall, and the Pinetum.  The collection is rich in species, cultivars, and hybrids, representing over 150 taxa.

Fall color of the majestic Quercus phellos. photo credit: R. Manduca

Our most recent NAPCC collection is the oaks. We are part of a multi-institution group which represents the genus, Quercus in North America.  Because oaks are found in many  geographical regions of the world it is prudent to have a variety of institutions collectively hold this collection.  For example, the UC Davis Arboretum can grow the California and Mexican oaks while the Scott Arboretum can focus on Eastern U. S. native species along with European and Asian species and cultivars.

Quercus bicolor with lovely fall color. photo credit: R. Manduca

Each of the three collections span the entire Arboretum.  Exploring any of these collections will open your eyes to the range of plants growing here at Scott Arboretum.

As the leaves fall and vibrant colors fade, the stalwarts of the garden take center stage. Blending pleasantly into the background during the growing season, evergreens provide that splash of green we seek in the dreary winter months. A staple found in many gardens for this winter green is juniper.

The bronze gold foliage of Juniperus x media 'Old Gold'. photo credit: R. Robert

Junipers come in variety of sizes, habits, and colors. Named for its bronze gold foliage, Juniperus x media ‘Old Gold’ holds its unique color through the winter months. Placed in full sun, the thin needles appear as golden yellow lace-like foliage as new growth.

Juniperus x media 'Old Gold' planted along loading dock entrance of McCabe Library. photo credit: R. Robert

This low/medium height shrub serves well as a foreground planting or colorful accent. A mass planting screens the loading dock to the McCabe Library on campus.

‘Old Gold’ responds well to trimming and can be maintained at a variety of heights and shapes. These trimmings provide a great accent of color in arrangements or in your holiday wreath. The touch of gold contrasts well with the blue tones of Juniperus virginiana ‘Grey Owl’ in green wreath created at the Scott Arboretum.

Green Wreath Workshop participants use various textures and colors to create striking wreaths. photo credit: R. Maurer

Experiment with the subtle color tones of ‘Old Gold’ during the Green Wreath Workshops at the Scott Arboretum from Thursday, December 1^st to Saturday, December 3^rd. Take home this and other great accent greens at the Holiday Green Sale on Saturday, December 3^rd from 10 am to 2 pm.

Massey Burke prepares the site for the construction of the Beardsley Earthen Wall. photo credit: R. Robert

Massey Burke has been teaching and practicing natural building techniques for seven years. She has built homes to park benches from clay soil, straw, and sand. “Most Americans have never lived in anything truly hand-built,” Burke says. “We are so accustomed to stick-frame structures it has come to seem normal. We don’t realize that most of the world does not live this way, that in most other countries people build with whatever is at hand.”

In 2009, Sasha Rabin and Massey Burke founded the company Vertical Clay. Vertical Clay works primarily with clay soils, local biodegradable fibers, aggregate, found and recycled materials employing the techniques of adobe, cob, earthbag, superadobe, straw clay, clay wattle, wattle and daub, earth and lime plasters, earthen floors and certain kinds of bamboo and strawbale construction.

Burke notes the sustainability of earthen construction, remarking that earthen walls weather slowly, don’t burn, can’t be eaten by insects, and can be reused. With an anticipated life of two years, the Beardsley Earthen Wall is located behind Beardsley Hall near the Viburnum Collection.

Professor Syd Carpenter and student volunteer prepare clay for construction of the Beardsley Earthen Wall. photo credit: R. Robert

Massey was invited to construct this distinctive wall by Professor of Studio Art, Syd Carpenter. While over 30 community members, Arboretum volunteers, and students from across campus are helping to “play in the dirt” and construct this earthen wall, Carpenter’s class, entitled The Container as Architecture, have tackled this installation as a class project.

Massey celebrated “I would love to come work on such a project at Swarthmore.  What you propose unifies most of why I practice earthen construction – its capacity for artistic expression, its ability to provide a tangible focus for sustainability dialogue, its interdisciplinary nature and its accessibility to what I call “unconventional work crews (students, volunteers, communities). “

You can see the foundation of the Beardsley Earthen Wall. photo credit: R. Robert

Carpenter commented that the rain has not damped the construction efforts. The rain doesn’t hurt the clay and the volunteers dry out. Come experience the art of natural building at the Scott Arboretum and see a whole new way to get your hands dirty in the garden.

A comical moment at the Plant Sale with Eve Thyrum and her husband, Per. photo credit: D. Mattis

I consider connoisseur plants to be:

• rare new plants that are available only through small specialized nurseries, or
• hard to find choice plants long known in horticulture literature but rarely available in the trade.

Below are some wonderful examples of connoisseur plants, all of which I have grown except for Aesculus wangii.

Choysia 'Aztec Pearl' in bloom. photo credit: Scott Arboretum Archives

Choisya ‘Aztec Pearl’ – I actually love this plant just before its pearl-like flower buds open.  Clusters of pinkish round buds, set against finely cut, trifoliate leaves, appear as bursting fireworks and add just as much ornamental value as the highly fragrant, almond-scented corymbs of white flowers that follow.

Deutzia sechuenensis var. corymbiflora – I’ve been growing this long-blooming, rare shrub for at least 10 years and without fail, every late spring as I walk by this plant, its beauty beckons me to observe closely its numerous sprays of starry, white flowers.  I then comment to myself, wow after all these weeks, I can’t believe it is still in full bloom and looks so perfectly beautiful!

Edgeworthia chrysantha ‘Akebono’ – One of my most prized plants in the garden – I love its scaffolding architecture of thickly rounded, smooth, tan branches which are adorned with plumeria-like foliage.  I prune to keep it open.  After foliage drop in late fall, flower buds emerge, quickly becoming fuzzy, silvery and fat, and then opening to a fragrant display of cinnamon-red flowers.  Definitely plant it near a window or walkway to enjoy during the winter months.

Bright red petioles of Emmenopterys henryi. photo credit: D. Mattis

Emmenopterys henryi – It’s rare in the forests of China and probably rarer in cultivation.  Supposedly taking many years to flower, two trees have recently bloomed at Quarryhill Botanical Garden in California after only six years.  So my hope to see it in flower spurs me on to adoringly appreciate this tree – it’s the anticipation!  Right now I’m enjoying its large, lush, dark-green, highly textural foliage with its bright red petioles.

The attractive shrub Helwingia japonica 'Golden Boat'. photo credit: R. Robert

Helwingia japonica – I planted this shrub just to observe its unique growing habit. Small clusters of ivory flowers emerge smack dab in the middle of each leaf.  Unfortunately I do not have both sexes: for if I did, I would then be able to enjoy the black berries which appear as if glued onto each leaf.  To ensure berries, plant at least 3 plants, or better yet 5, to increase your chances; these plants are always sold unsexed.

The elegant and charming shrub Platycrater arguta. photo credit: Scott Arboretum Archives

Platycrater arguta – Another prized shrub, quiet, elegant, and charming, even when not in flower.  Upon watching one grow at Scott, I was pleased to see it offered at the 2009 sale and I secured one immediately.  After 2 years, it has aged into a perfectly rounded shrub with a dainty, mounding habit and soft-spoken flowers.  This hydrangea relative has dangling clusters of white flowers.  Since it is on the subdued side, I prefer pairing it with other plants that feature texture over bloom, i.e., ferns, small hostas, and Solomon’s seal.

Aesculus wangii – This is a plant I don’t grow, but it is at the top of my list to bring home from this year’s sale. To quote Andrew Bunting “it’s the rarest of rare.”  Threatened by habitat loss in China and Vietnam it is on the International Union for Conservation of Nature and Natural Resources “Red List” as vulnerable.  So I feel compelled to plant one to preserve it from extinction.  It bears enormous, 18” long panicles of purple-spotted yellow flowers followed by 4” diameter seeds – how can I resist!

Selecting those connoisseur plants at the Scott Associates Plant Sale. photo credit: K. Bock

Good sources of connoisseur plants are typically specialty nurseries and arboretum plant sales including the Scott Associates Plant Sale, September 16^th through 18^th.

Finally, it’s the people, not the plants, who are actually the connoisseurs.  Anyone spending time in study and appreciation of plants can achieve some connoisseurship.  Most important is pleasure, and each of the many plants at the Scott Associates Plant Sale will bring you the opportunity for long-term appreciation.

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Eve Thyrum is an enthusiastic garden who has written for Fine Gardening, been featured in Southern Living, named member of the year for the Hardy Plant Society, and served as chair of the Scott Associates Plant Sale to name a few of her horticulture accomplishments. She also researches and authors all the Plant Fact Sheets for Scott Arboretum Horticulture Seminars. For the 2011 Plant Sale, she serves on the Education Committee.

Fallen Catalpa in the Catalpa/Magnolia Collection. photo credit: R. Robert

The Crum Creek flowed through its flood plain including Rogers Grove and the newly established riparian forest buffer, cresting at the feet of the James R. Frorer Holly Collection.

The Crum Creek flowed into its flood plain bending these saplings in the newly establish riparian forest buffer. photo credit: R. Robert

The hurricane and major thunderstorms that have recently passed through the area have given our stormwater management strategies quite a workout. Check out the video below to see how stormwater features can be an attractive feature in your garden. This was filmed after a 1.95 inch rain event this August.

To help you envision fall colors and cooler weather, here is a delightful video developed by WHYY about the Scott Arboretum. Look for this video to appear on your local WHYY TV station.

Learn more about the organic lawn in these past posts.

Announcing the Organic Lawn Brochure and Blossoming Research Effort

Remediating Compaction on our Organic Lawn

Organic Lawn Consultation with Eric Fleischer

Organic Lawn Care

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.

Last week our fellow public garden Winterthur was featured on ABC’s Bachelorette as the most romantic spot for a picnic. Well not to brag, but Scott Arboretum boasts some wonderful picnic locations as well. Check out our top five locations. Some are well known, while others are hidden gems.

Parrish Lawn on a relaxing fall afternoon. photo credit: R. Maurer

5. Parrish Lawn – The large swath of lawn in front of Parrish Hall is ideal for those who enjoy people watching. Located in the heart of Swarthmore College campus, picnickers enjoy the comings and goings of campus and arboretum life. This expanse of lawn is bordered by majestic Swamp White Oaks which add the gentle rustling of leaves as background noise and a colorful backdrop during the fall.

Adirondack chairs make a great location for a picnic. photo credit: R. Manduca

The lawn also has comfortable and picturesque Adirondack chairs to pull into a cozy circle or for relaxing in a shady spot.  Parrish Lawn features the big Adirondack chair for a wonderful photo op and a great spot for kids to climb.

Mark and Jenna Buehner enjoying an afternoon swing in the Conifer Collection. photo credit: R. Robert

4. Conifer Collection Swing – Tucked in the Conifer Collection is an old-fashioned wooden rope tree swing, the type you would find in Forest Gump’s front yard. This delightful swing is an ideal spot for your picnic and a romantic sway for you and your Jenny. Suspended from the grand Liriodendron tulipifera, the swing is in an idyllic setting among the stately conifers.

Sunsetting across the pond in the Terry Shane Teaching garden. photo credit: D. Mattis

3. Terry Shane Teaching Garden – A favorite spot of Arboretum volunteers, the Terry Shane Teaching Garden offers the ambiance of a tranquil shade garden with a pond. Nestled behind the Cunningham House, the offices of the Scott Arboretum, this garden features a charming pond with a gentle trickle of water emerging from a whimsical cat statue. This kitten, named Mina, appears to be playfully batting at the goldfish in the pond.

An inviting picnic spot among the containers of the Terry Shane Teaching Garden. photo credit: R. Robert

This lush garden has inviting benches and chairs positioned under the cooling foliage of a shade garden. Sometimes referred to as the curator’s play ground, the Terry Shane Teach Garden is where our curator, Andrew Bunting, trials many of the new plants for the campus. There are numerous remarkable plants awaiting discovery here.

A romantic picnic at the whisper bench. photo credit: R. Robert

2. Whisper Bench – The ideal location for whispering sweet nothings into your sweetheart’s ear is the whisper bench. Hidden at the edge of the Cherry Border with a sweeping view of the weeping cherry allee, this bench is secluded for a romantic picnic. In April when the Cherry Border is in full bloom, the bench is bathed in delicate pink and white petals.

True to it’s name, the whisper bench carries the sound of whispers form one side to the other. A couple can sit at opposite ends and whisper to one another without another soul hearing a word.

Enjoying the ideal woodland picnic in the Scott Outdoor Amphitheater. photo credit: R. Robert

1. Scott Outdoor Amphitheater – Situated under the grand canopies of Liriodendron tulipifera, the elegant, lawn-covered stone tiers of the Amphitheater provide a relaxing view of the Crum Woods for your perfect woodland picnic. When you are situated in the Amphitheater at the heart of campus, you would never know what is going on outside of this peaceful natural theater.

A favorite lunch location for Woody and Perennial Plant Conference attendees, most days you will find only one or two people enjoying the tranquility of this natural cathedral. The gentle green terraces and cooling shade of tulip poplars offer a memorable spot for your picnic blanket.

Picnicking among the stately conifer collection. photo credit: R. Robert

Explore the many perfect picnic spots at the Scott Arboretum.

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.