Saturday, March 8, 2008

Spring comes to Fern Valley...and the rest of the Arboretum!

It may have been gloomy yesterday in Washington, but nighttime temperatures stayed right around 10C and we got over 1.5cm of rain so spring moves steadily forward. In Fern Valley the ephemerals are up. Look along the road behind the stone swale and under the big beech tree. On Monday there was nothing but a few residual snowdrops that I removed. By Wednesday Virginia bluebells, Sweet Betsy (Trillium cuneatum), and Toothwort, had forced their way out of the soil; by Friday, the Toothwort had visible buds, the Trillium leaves had unfolded to reveal their lovely mottling, the Virginia bluebells had pushed up to almost 10cm, and a Bloodroot had gone from non-existent to a fist sized bundle ready to expand.

The essence of Spring is change and you have to get out there and look or it'll pass you by; because of the incredible taxonomic range of its collections, the National Arboretum might be the best place in the area to watch spring approach. Cherries are beginning to flower, 'Okame' is almost in full bloom. The research collections contain a variety of common and obscure taxa; many are showing color. We have a wide variety of early flowering magnolias and they are beginning to open. Many spring flowers are fragrant; Prunus mume, the flowering apricots are out in their olofactory glory, and the winterhazels are opening and the witchhazels are moving through their season. It goes on and on and its started!

Thursday, March 6, 2008

National Zoo Faux Bamboo Deer Fencing?

Lets have two pictures in a row without any living plant material! As part of my inservice training, I attended a lecture/walk at the Zoo about their new "Asian Walk", a wonderful few acres in which they display a handful of interesting Asian animals including Giant and Red Pandas in areas approximating their natural environment. The "bamboo" that you see in this picture is mostly metal fencing. I didn't talk with the fabricator, but it looks like they took galvanized pipe and laid welding beads around it at appropriate intervals to approximate the "rings" around bamboo canes, painted them and set them in concrete. Every 6th or 7th or both was painted the yellowish color of dead canes. Small (10"-16") rods were welded towards the top, 5-10 per pipe to represent the branching stems that hold leaves. Admittedly this is a somewhat non-realistic approach, and could not have been inexpensive, but it looked great and could be copied for use as deer fencing since it is 10-12 feet tall. Possibly the sculptural and open nature of the construction would exempt it from regulations that allow fences to be only 6' tall. We all know a 6 foot fence does not stop a determined deer.

Another interesting feature included in this exhibit space was a rock wall made up of loose stones filling galvanized cages, or gabions. The gabions, each approximately 2'x6'x3', were lined up and stacked to makes a wall at least 15' tall and 50' long. They are attempting to grow hostas and epimediums in sphagnum stuffed in the face of the wall with some apparent success though they were dormant now. The concensus among our group of expert horticulturists was that a more thoughtful choice of plant material would make maintenance easier and produce a more interesting effect. Their plant selections were no doubt influenced by the fact that this is an Asian exhibit. I would like to see the same construction planted with lichens, mosses, violets, ferns on a dark site, or conversely in the full sun planted with "shale barren" or Mediterranean plants. No doubt lists of plants for roof gardens would be productive sources of taxa for these sites.

Wednesday, March 5, 2008

Philadelphia Flower Show and Native Plants

One of my favorite blogs recently reminded me of Michael Pollan's "Anti-Nativism" letter to the New York Times. in their interview, they offered him the chance to repudiate or even to compromise his fairly extreme position. He declined. Okay. It is the nature of debate that there is polarization and that all participants fit somewhere on a scale from moderate to extreme. Yes, the extreme positions are always wrong on both sides of an argument, but for the dialectic to function, both sides need to exist. Almost all of us have been embarrassed by the extreme members of our particular team. Still, attacking our own side just shifts the balance in the wrong direction.

Which brings me to my point today; the pendulum seems to be swinging in the wrong direction, Anti-Nativism seems to be winning. I saw no displays of any consequence, and here I am being generous because I don't remember seeing ANY displays dealing with native plants. Indeed, even a wonderful feature explaining the importance of wetlands and beavers,... had specimens of Miscanthus sinensis, definitely an invasive in our fields. Wow!

I loved the show. It was themed towards Jazz and New Orleans; the exhibits were over-the-top colorful. The bromeliads were spectacular. And plentiful. Rich crimson decadence was everywhere. It was one of my all time favorite shows. But still...maybe we could have had some attention paid to good native garden plants.

Tuesday, March 4, 2008

A Respite from Early Spring??? and Sky Pencil Holly

Its the 50F degree nights that force spring's hand. This morning it is 57F so here goes the season. Ironically enough we are headed today to the Philadelphia Flower Show. Flowers shows, I think, have traditionally been scheduled to help us get through that final bit of winter. What with Global Warming, spring comes so early that today we will be spending the day inside looking at forced plants while the season surges forward and temperatures climb to shirtsleeve levels. when I need a respite from winter, if we can't go to Florida, I conjure up images of warmer days. This picture of the Adelphi garden is obviously late summer, witness the flowers on Laerstroemia x 'Dynamite' and the size of Musa basjoo, the hardy banana.

Another ineresting plant visible on the left side of the picture is the 'Sky Pencil' Japanese holly, a fastigiate cultivar of Ilex crenata; it grows, ultimately, to about 12' high and only 1-1.5' in diameter. A critically useful plant in garden design, this was introducted by my employer, the US National Arboretum. It is one of a handful of evergreens that are this strictly columnar. While I like it as an accent, I have used it many times in designs to flank doors, stairways, walks, etc. There are places, like adjacent to a side door close to the property line, where a row of 'Sky Pencil' hollies can be a great visial barrier. Other evergreens would be too wide (or might reqire more sun) and fences can normally only be 6' high. Still, I love it as an accent in the mixed border!

Monday, March 3, 2008

Florida: Pinus palustris bed

This is an island bed that we created in December 2006. It is a mixture of natives and non-natives. Pinus palustris, now only 3' tall, will be the dominant plant. If it is not the most beautiful pine in the world, it is in the top two. Vast stands of this pine were historically the dominant feature of much of the SE coastal plain, but without fire as part of the cycle, those areas are eventually taken over by hardwoods. The sun loving pines disappear. On public lands throughout the south there are regularly scheduled "programmed burns" and the numbers of Longleafed pine are increasing.

Its a good tree for a garden because not only is it beautiful, as it matures it lets a lot of light through so there is enough sun for a wide variety of underplantings. You can see a variegated agave, a nice structural accent, and a host of other specimens. We were last in this garden in early January but we're going back in about one month! Interestingly the dry season in Central Florida runs from early winter to mid-spring so it will be exciting to see how things have done.

Sunday, March 2, 2008

Cornus sanguinea 'Midwinter's Fire'

32 F this AM; not so warm as yesterday when the morning chorus of birdsong drew me outside and resulted in this picture!

When the sun is low on the horizon, just after sunrise or before sunset, it sets this plant afire in an eponymous incandescence. It is very cool...or hot. Twigs and stems are green when temperatures are warm, but assume these incredible colors: at one time, the stems grade from apricot, through gold, to a range of oranges almost reaching red. Wow! The generic form of Cornus sanguinea, the Bloodtwig dogwood, is native to most of Europe and parts of Western Asia. This selection has been in the trade a relatively short time. It grows into a gawky fairly formless large shrub with nondescript leaves so we coppice it, that is, cut it almost to the ground, every spring. It is easily grown and fast, not requiring any special treatment.

I have a few suggestions regarding its use. First, consider its location in relation to the winter sun. It is best viewed early or late, with the sun behind the viewer. Second, while it can be used effectively in mass plantings, it is often more effective as a specimen. Third, since its summer presence is not a real addition to the garden, and the new growth colors more effectively, conside coppicing.