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!

Barb noted she bases her home plant selections on a strict interpretation of “native”—giving the highest priority to plants she knows are indigenous to SE Pennsylvania and the Piedmont area. As an avid bird-watcher, her comments derive from many hours of observation of animals and insects. She recommends:

Asclepias tuberosa. People are starting to see milkweed as more than a roadside plant. Milkweed flowers are a nectar source for many butterflies and the leaves are the only food source for monarch butterfly caterpillars. Gardeners can watch the entire monarch lifecycle on this plant.

Lobelia cardinalis is scattered among iris around the pond in Barb Elliot's backyard. photo credit: T. Patterson

The nectar of Lobelia cardinalis, cardinal flower, is highly valued by hummingbirds and is a prime target during its late summer bloom time.

Phlox paniculata 'Jeana' photo credit: B. Elliot

Phlox paniculata ‘Jeana’ is a new mildew-resistant cultivar. It is great for butterflies and hummingbirds.

All of the aforementioned plants are available at the 2011 Scott Associates Plant Sale. Nearly one-third of the plants offered—both the woody shrubs and trees and the herbaceous perennials—are native to the eastern US.

Check out the large plant selection at the Scott Associates Plant Sale. photo credit: K. Bock

You can get complete descriptive and cultural information on the plants Barb mentioned from the full sale handbook, which is an easy download.

In addition, the group of native plants available is an excerpt listing in the “Plant Suggestions for Specific Needs,” page 51 in back of the handbook. For your convenience, we’ve reprinted it as a one-page list here.

Here is the detailed criteria Barb Elliot applies in selecting her plants for habitat gardening.

• Does the plant have multiple uses for wildlife, beyond food?
• Will having the plant on my property contribute to meeting year-round wildlife needs for food, shelter, nesting places?
• Is it an important host plant, increasing the opportunity for reproductive success for insects and birds?
• As a food source, is the nectar or pollen prized, is the foliage attractive to leaf-eating insects, is the bud/berry/seed/nut eaten by birds?
• Does the plant foliage provide protection from predators/weather; is it useful for nesting birds?

Enjoy a garden of any species by planting for all your neighbors, not just humans.

==================== >< ===================

Barb Elliot, Ph.D. in Educational Psychology, trained as a reading specialist, worked for GE Aerospace, retired from market research at AstraZeneca, and lives in Wayne, PA.

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.

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

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.

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:

The Scott Arboretum has published a brochure detailing the concept, practices and research behind the Organic Lawn Initiative. You can view it online at http://www.scottarboretum.org/publications/OrganicLawnBrochure2-11.pdf or pick up a copy from the brochure box at the organic lawn, installed just below the stairs of Magill Walk.

Four Swarthmore College biology majors are studying the biological diversity in our soil and the effects of our organic and conventional landscape maintenance practices on soil organisms. Such knowledge will improve our ability to maximize soil fertility and plant health by harnessing natural ecological processes. Organisms including fungi, bacteria, protozoa, nematodes, and earthworms are the key to organically improving the structure and chemistry of the soil– the life support system for plants. On April 6th, Elaine Ingham, Ph. D., — internationally respected soil microbiologist, Chief Scientist for the Rodale Institute, and President and Director of Research at Soil Foodweb Inc.– will spend the day at Swarthmore training students, as well as several of the College’s science faculty and horticultural staff, in the use of a light microscope to identify microbes and analyze the quality of soil, compost and other biological materials. We are thrilled to bring together such a diverse group of constituents to learn with and from one another.

By Isabell Newlin, Good Food student worker

Elm Street, which runs by the President’s house and the Good Food Garden, is lined with sugar maples. If you have walked down this street in the past few weeks, you might have noticed a couple of blue bags hanging from the trunks. This winter a few of us (Swarthmore students) tapped three of these maples, and we have been boiling the sap down to make syrup.

Equipment used to collection the sap. photo credit: B. Dair

To tap a maple you need a drill (7/16 in), a spout, a mallet, and a bucket. As the days get warmer and temperatures rise above freezing, the difference between day and night generates pressure in the roots of the maples and their sap runs up from the roots into the trunk and branches.

Drill a hole about two inches into the tree and tap the spout into it with your mallet. Angle the drill upwards at a very slight angle so that gravity will draw the sap down into your bucket. At the end of the spout is a hole, to catch the sap is coming upwards from the roots. There is a hook on the spout on which to hang a bucket, or bright blue bag. In the Delaware Valley, the sap often starts running at the beginning of February, when it first gets up to 40 degrees F.

The amount of sap we get each day varies a great deal. When it is warm, more than a gallon; when it is below freezing, very little. Sugar maples, Acer saccharum, have the highest concentration of sugar in their sap, but you can make syrup out of the sap from silver maples, Acer saccharinum, and black maples, Acer nigrum, too.

Blue bags used to collect sap. photo credit: B. Dair

We have collected about 20 gallons of sap over the past two weeks, which as syrup is very roughly 1/30^th its original volume.

By Erin Curtis, Student Organic Lawn Coordinator

The Arboretum recently achieved another step in the transition to an organic lawn maintenance program for Mertz field. We had a demonstration of the “AERA-vator” aeration machine, which loosens highly compacted soil to induce root growth in plants and facilitate nutrient dispersal in the soil. This is a crucial step included in the protocol from our consultant, Eric T. Fleisher. Before our first batch of compost tea is applied, we need to loosen the soil so that the liquid can penetrate further and facilitate microbial activity deep into the root zone.

Not only does compaction limit the depth of percolation of water and nutrients added by the gardener, but also the natural movement of soil organisms that digest and mix organic matter. Compaction occurs when an outside force compresses soil particles together so that little air space remains underground. Healthy soil consists of about fifty percent air and water, which is necessary for plants adequate access to nutrients. Compaction also physically impedes root growth, which in turn limits the plants ability to soak up water and important nutrients. The grass roots are unable to reach farther into the soil and thus cannot access as large a volume of soil along with the water stored in it.

Foot traffic from Mertz dorm to Sharples dining hall has caused this browning of Mertz field. The compaction of the soil has caused the grass to die and be replaced by weeds. photo credit: E. Curtis

As the picture above shows, many weeds have colonized in the grass of Mertz field. In particular, annual bluegrass, white clover, plantain and dandelions are a problem. The vigor of these species over that of turf grass is usually an indication of soil compaction, as these weeds are adapted to survive and thrive in compacted soil. Without addressing the underlying problem of compaction, however, the prevalence of the weeds cannot be combated. Thus, compaction not only has direct effects on roots and retention of water and nutrients, but it also has indirect effects, including that of invasive weeds outcompeting the desired turf grass species.

Compaction is a significant problem in many fields — but what causes this compaction? The compacting force can come from vehicles, heavy machinery, or even foot traffic. Compaction is a common problem on lawns everywhere, and Mertz field is no exception to this where it is difficult to dig even a small hole in the soil. The field has daily human traffic and was heavily compacted by machinery during the construction of Alice Paul and David Kemp Residence Halls.  The field also served as the main practice field for the Ultimate Frisbee team for years.

To solve the problem of compaction, many school districts, municipalities, and athletic organizations use aeration: a large machine churns long tines into the soil, loosening it and introducing air gaps. Our aerator of choice is the “AERA-vator” from First Products — the same aeration machine used by the Phillies. The tines in the AERA-vator vibrate to fracture the soil both underneath and around the machine rather than simply pulling out a plug of soil; this way, the soil is loosened over a wider area and to a greater depth than the tines actually reach. The aerator previously used, a standard type that pushes down under its own weight and pulls out plugs, cannot penetrate even to the full depth of its tines through soil as dense as ours. An aerator that is able to combat compaction effectively is essential for a successful organic lawn.

The AERA-vator apparatus broke through the soil in Mertz field on a beautiful October day when the field was dry enough to aerate.. The first two attempts had to be rescheduled due to weather — when the soil is too wet after a heavy rain, the aeration can do more damage than good, potentially ripping grass from the soil, and the heavy tractor leaving excessively compacted tracks.

The demonstration of the AERA-vator. photo credit: E. Curtis

The machine arrived by truck and was towed by tractor to Mertz Field. The company representative led a group of staff from Grounds and the Arboretum through a demonstration of the machine. The aeration happens through an apparatus towed by the tractor: a large cylinder with many slender 4” tines that vibrate back and forth as it moves forward across the lawn. While in the soil, these tines move back and forth, fracturing the soil between them, rather than just puncturing holes in the ground.

The AERA-vator was indeed effective at loosening the soil, at least in the first few inches: after a pass with the AERA-vator, the ground was noticeably softer to the step. When the compaction was measured with a penetrometer, a device that measures the resistance from the soil when a probe is inserted, the compaction pressure went from about 13.5 force-pounds to about 10 force-pounds, and the probe sank deeper into the soil before it encountered measurable resistance.

After the field was aerated, we were able to begin the application of compost tea. During the month since the field’s aeration, we have brewed and applied about 500 gallons of compost tea to the five acres. Through the winter and early spring, we will have compost — made from the College’s own garden trimmings and dining hall refuse — sifted and spread thinly over the lawn. The infusion of organic matter will add nutrients and will improve the ability of the underground environment to exchange and retain these nutrients and feed the ecosystem of organisms that the compost tea introduced.

Next spring, we will repeat the aeration process and compost tea application, as well as over seeding with a mixture of vigorous turf grass species. Keep your eyes out for more photos and details in a Hybrid article about the organic lawn project soon!

As we continue our series on how to overwinter tropicals, we have discussed plants with bulb, rhizome, tuber, fleshy root including Musa, Canna, Alocasia, Colocasia, Xanthosoma, Hedychium, and  Alpinia.

Purple flower of Tibouchina. photo credit: R. Manduca

The next types of plants are those which you will not cut back, but will still allow to lose their leaves and go dormant. These include such plants as Tibouchina, Brugmansia, Euphorbia cotinifolia, Plumeria, and Melianthus major. If they are growing in a container on your patio and the container is of a reasonable size, you may want to keep it in this container for the winter.

If the container is too large, the plant can be transplanted into a smaller plastic nursery pot for ease of handling over the winter. If transplanting is necessary make sure that the plant is transplanted into the nursery pot without causing too much damage to the roots. Again, filling in the extra space in the pot with bark mulch is good. Once the weather becomes cool at night I would consider bringing these plants into the basement. Once situated in the basement they will start to go dormant. You may need to cleanup around them as the leaves will brown and fall off.

Agave 'J.C. Raulston' works well as a houseplant. photo credit: R. Robert

Finally, the last group of tender plants that are worth keeping as whole plants are those which do not die or get cut back. This group would include bromeliads; Phormium, New Zealand flax; Dianella, Agave; cactus; etc. These plants cannot successfully be kept in a basement because they are still actively growing during the winter. Keeping them over the winter if you do not have a greenhouse can present a problem. If you just have a small number, they can be dispersed through the house and treated as houseplants. If you have a sun porch, this will remedy part of your problem.

An unheated or slightly heated sun porch will save you a lot of trouble finding homes for these plants. Even if it gets into the 40’s many of them plants will be fine. Phormium, Dianella, Agave and cactus can all take reasonably cold temperatures. During the winter they will not grow very much so you want to keep the soil on the dry side. Too much water will result in the plants rotting.

Before you bring them into the house in the fall make sure the plants have been deadheaded, old leaves removed, and you have checked them carefully for pest and disease problems. As a precaution, you may want to drench them with an insecticidal soap.

Bromelid growing in the Annual Border of the Terry Shane Teaching Garden. photo credit: D. Mattis

For bromeliads and perhaps more tropical-type house plants you need to find warmer locations. Bromeliads make attractive house plants for the winter. The advantage of keeping bromeliads from year to year is that they will get bigger and bigger. Again, checking for pest and disease problems is important before integrating them with your other houseplants.

All these are viable and easy methods for over-wintering plants for those of us who are not fortunate enough to have access to a greenhouse. Once the plants are packed away in the basement, there is very little you have to do for the remainder of the winter. Those plants which you have brought into the house can simply be treated as house plants.

Once spring arrives, all these plants can be placed back into the garden around the middle of May. These methods create ways for the average homeowner to amass an interesting collection of tropicals and tender perennials without the aid of greenhouse.