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.

Colorful array of magnolia fruit collected from the Scott Arboretum, Henry Foundation, and Morris Arboretum. photo credit: J. Coceano

We have gathered seed from the Arboretum’s collections, as well as from the Henry Foundation in Gladwyne and the Morris Arboretum in Chestnut Hill.

Stack of follicles bursting with magnolia seeds. photo credit: J. Coceano

Most magnolia seeds are found in large cone-like fruits called follicles.

Magnolia seeds removed from follicles and ready for soaking. photo credit: J. Coceano

Once the follicles open up and reveal the seed which is often red and covered in a waxy coat, the seed can be harvested.

Once removed from the follicles, seeds are soaked for three days. photo credit: J. Coceano

After the seeds are harvested, they are soaked in water for three days in order to loosen the seed coat. Our volunteers found the most effective way to remove the seed from the seed coat after soaking was to squeeze the fruit. The seed simply squirts out of the fruit.

Cleaned seeds are allowed to dry for a day. photo credit: J. Coceano

The seeds are then dried for a day or two. The seeds are packaged in slightly moist vermiculite and refrigerated. Do not store the seeds dry, because they rapidly lose viability under those conditions.

Arboretum Assistant (volunteer) Marianne DiPaulo packages seeds in moist vermiculite. photo credit: J. Coceano

The moist seeds are stratified for 2 to 4 months at 32 to 41 degrees Fahrenheit before planting. You can also fall- plant the seeds outdoors to allow nature to provide the cool, moist conditions for stratification.

Throughout the process it is important to keep the name and the source with the seed.  Those who subscribe to the Magnolia Society’s seed exchange will make their selections based on species and source. To learn more about the Magnolia Society International and to participate in the seed exchange go to: www.magnoliasociety.org.  Also, consider attending the next annual meeting in the Bay Area and Sonoma Valley.

As a whimsical aside on the wonders of seed germination, enjoy this video of our former summer intern, Jared Barnes impersonating our favorite super hero, Superseed. Happy propagating!

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.

Gardeners, Dwight Darkow and Sue Stark, pose for a whimsical photo. photo credit: D. Mattis

Sue noted, in addition to wildlife benefits, she was interested in plants that establish strongly—that could fill bed spaces, replace lawn, and in particular be an alternative to ivy. In many cases, she gave examples of how the plants have been used around the campus and how they performed.

Here, Sue highlights a few of our birds-and-bees plants, with a focus on ground covers:

Tiarella cordifolia ‘Susquehanna’: This is an example of an ivy replacement. It spreads quickly. Tiarella sp. is said to tolerate a wide range of soil conditions, including alkalinity, which means you can use it near the runoff from a concrete walk or roadway. This is one of the so-called “river series” of foamflower cultivars, named for eastern Pennsylvania rivers. T.c.‘Susquehanna’ is said to have more red in the leaf.

Speaking of ground covers, Waldsteinia ternata, barren strawberry, is also on the sale list. We used the native version, Waldsteinia fragarioides, around the campus as cover under shrubs. Step out of your car in the new Wister Center parking lot and you’ll find it nearby.  Walsteinia also works great with spring bulbs. W. ternata clumps more, doesn’t run out as much as our native, and perhaps can take the heat a little better, but either is an attractive cover.

You have to consider the ‘Gro-low’ cultivar of Rhus aromatic, a worthy native ground cover. We use it on campus near Alice Paul Hall, and it takes off. Bees will be busy around the spring flowers, birds are attracted to the berries, and the red-purple fall color is a delight.

Spigelia Marilandica in bloom. photo credit: Scott Arboretum Archives

Spigelia marilandica is another native perennial worthy of more attention although it is slow to emerge, it’s tough, and has a red flower, which draws the hummingbirds. We use it extensively near the entrance to the Scott Amphitheater.

Red flowers of Aesculus pavia. photo credit: R. Pineo

Also of interest to hummingbirds is the red flower of Aesculus pavia, red buckeye. We have ‘Biltmore Strain’ in the sale. It blooms earlier than the bottlebrush buckeye, Aesculus parviflora, and drives the hummingbirds wild. Whether you consider it a shrub or a tree, it will clump out nicely. You can see it used on campus near the Dana/Hollowell dorms.

Back among the perennials, I’ll mention Phlox paniculata ‘Jeana’ on the sale list. Commonly used, the Phlox flower has the attractiveness and attraction-interest of the non-native Buddleja sp., without the drawbacks. This new cultivar has 2 important virtues: it is very mildew resistant, and does not grow as tall as straight species making it less likely to flop.

Striking yellow flowers of Gelsemium sempervirens 'Margarita'. photo credit: R. Robert

Finally, we should consider a plant that is not listed as an “East-of-the-Mississippi” native—the Gelsemium sempervirens ‘Margarita’. Commonly called Carolina jasmine, this is a U.S. plant, but is found further south and out of our indigenous area. However, this selection has proven hardy up through zone 6. It has very fragrant, yellow, trumpet-shaped flowers that bring in butterflies and hummingbirds. It’s a vine that can be trellised vertically, or grown horizontally along a fence, or as a groundcover. Plus, it is a Pennsylvania Horticultural Society Gold Medal winner.

You can get complete descriptive and cultural information on the plants Sue mentions from the Plant Sale Handbook.

In addition, note the excerpt listings starting at page 53 in the back of the handbook, the “Plant Suggestions for Specific Needs.” Two categories particularly relate to our discussion here—the Native Plant list and the Winged Wonders list (for bird and pollinators). For your convenience, we’ve reprinted each as one-page lists—Natives here and Winged Wonders here. Read about other great wildlife and conservations recommended by Habitat Steward, Barb Elliot.

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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.

Plant catalogs can make a good addition to your reference shelf. photo credit: R. Robert

These distinctive catalogs provide information above and beyond the standard plant picture and sun/shade requirements. The Scott Arboretum curatorial office collection of plant catalogs for reference includes Creek Hill Nursery, Pleasant Run Nursery, and Rare Find Nursery among others. These catalogs feature excellent plant pictures, informative cultural information, and insightful firsthand accounts of growing the plants.

The Plant Sale Handbook has more than a list of plants available at the sale. photo credit: R. Robert

Scott Associates Plant Sale Handbooks can also be found on many gardeners’ reference shelves. More than just plant catalogs for the Plant Sales, they feature detailed cultural information and insightful comments on the over 300 plants available at each sale. For example, this description elaborates on the virtues of Crytomeria japonica ‘Sekken-sugi’, Japanese cedar (page 17) in the 2011 Plant Sale Handbook.

The striking creamy yellow new growth shines like a beacon among contrasting foliage plants and gradually turns more green in the summer heat. Maintains its pyramidal form as it ages. Site where it will be protected from winds and extreme sunlight. Best when grown in light shade.

Blue plant tags indicate Plant Sale plants growing in the gardens of the Scott Arboretum. photo credit: R. Robert

The descriptive listings also identify the locations of plants at the Scott Arboretum. Thus gardeners can see how the plants grow in the garden. Cryptomeria japonica ‘Sekkan-sugi’ can be found near Sharples Dining Hall on campus.

Beyond individual plant descriptions, the handbook provides plant suggestions for specific gardening needs. For example on page 51 you can identify woody and perennial plants that deer might ignore. If you are a gardener with dry shade conditions, 15 plants are recommended for your garden on page 52.

These resource lists include:
Drought Tolerant Plants – page 51
Dry Shade Plants – page 52
Evergreen – page 52
Groundcover Plants – page 53
Native Plants East of the Mississippi – page 53
Wet Tolerant Plants – page 54
Winged Wonders Plants (to attract birds, hummingbirds, and butterflies) – page 54
Winter Interest Plants – page 55

In addition to considerations about individual plants, there are step-by-step instructions on planting containers (page 56) and balled and burlapped plants (page 57).

I encourage you download this robust tool to learn more about the plants you may already have in your garden or to get great gardening ideas for your unique growing situation. Members can pick up a bound copy at the Scott Arboretum offices or have a copy mailed to them for $3.00.  It is a great addition to any reference shelf.

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

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/2011/05/crum-creek-cleanup/ http://blogs.scottarboretum.org/gardenseeds/2011/05/crum-creek-cleanup/#comments Tue, 17 May 2011 20:05:11 +0000 Sue Stark http://blogs.scottarboretum.org/gardenseeds/?p=2973 We held our annual Crum Creek Cleanup event on Thursday, May 5th.  It was a gorgeous and very productive day.  We had 41 participants cover the Crum Woods from the north end of the woods to the south end.  Volunteers picked up trash from the woods and creek, cleared out water bars,  pruned branches and pulled invasives.  Thanks to everyone who came out for a rewarding morning of work.

Here are the totals for trash we took out.

3 tires

2 fibergalss poles

45 bags of trash

1 metal strap

1 large concrete blob

Picnic table parts

Various wood

1 Wooden bear

We held our annual Crum Creek Cleanup event on Thursday, May 5^th.  It was a gorgeous and very productive day.  We had 41 participants cover the Crum Woods from the north end of the woods to the south end.  Volunteers picked up trash from the woods and creek, cleared out water bars,  pruned branches and pulled invasives.  Thanks to everyone who came out for a rewarding morning of work.

Here are the totals for trash we took out.

3 tires

2 fibergalss poles

45 bags of trash

1 metal strap

1 large concrete blob

Picnic table parts

Various wood

1 Wooden bear

]]>

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.

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: