Saturday, October 4, 2008

Beltsville Library Saturday (Colchicum 'Waterlily" blooms)

I did addition by subtraction at the Library today. When I began taking care of the area, its plantings consisted of three trees, a number of shrubs, and a lot of hostas and daylilies. Too many hostas and daylilies. The hostas all burned. The courtyard is surrounded by brick walls, has a brick walkway, and gets a lot of sun. Its hot and they don't like it. Most had to go. I thought I was able to visualize the effect of changes in a garden, yet I am still surprised at how much better the area looks as a result of the removals. I'm keeping the dwarf daylilies and consolidating them, but removing most of the standard varieties. A few are nice, but I find the foliage tends to become messy and disgtracting from June to the end of the season.

The Colchicum 'Waterlily' are flowering now as the C. speciosum finish up. I planted three divisions of Rohdea japonica from the Adelphi garden last week and they are doing well. They will provide evergreen structure at gound level under the birch. I moved the Rhapidophyllum hystrix (Needle Palm) to the right. Last week I didn't have the resources to remove the giant clump of hosta where I really wanted it so I heeled it in near the Coral Bark Maple. It looks better where it is now. I planted a piece of Canna 'Bengal Tiger' from a container on the front deck. It is hardy and will add a foliage element that can relate to the Golden Banana. Next spring I'll add a Basjoo banana on the left-hand wall and there'll be a triangle of bold foliage.

Sternbergia lutea out of nowhere...not really, more out of the past

It's a good day when you learn something new or realize something important, so this is a good day. I found this Sternbergia under a rose in a front bed and remembered how it got there. About 8 or 9 years ago I divided a clump of these cheerful fall flowering bulbs and split the bulk of them between two locations. I remember now though that I took a handful of impossibly small bulblets and distributed them to random spots around the garden. This is the first of these plantings to come to fruition. It is a tough bulb and will inevitably become a clump and, if allowed, will, by seed, gradually colonize the bed it's in.

My epiphany though, was that all of our actions in the garden take different times to realize themselves. This sounds pretty obvious, but hey, maybe I'm not that bright. And anyway all epiphanies are patently obvious in retrospect; its just that explosion of awareness that makes them so wonderful.

I regularly think about time in the garden. Days and years are cyclical and roll along the linear passage of the years, but what about those finite fragments of linear time: 5 minutes to plant a flowering potted plant, 60 days to grow some annuals, 100 years to flower a Century plant, a lifetime to grow a mature shade tree. a year and a half to go from a 1 gallon pot to a beautiful garden perennial. And they are all layered on themselves like paper mache. I have always though that the idea that we had control over our gardens performce and evolvution was a bit of hubris. I'm not smart enough to do all those calculations. There's a lot of serendipity going on, or maybe the universe is helping us?

Sorry about the 4th paragraph but I have one more observation. If you are starting a garden you are waiting for results so its good to do the things that will give you a quick return; hardscape, annuals, perennials, a few big plants. Now the important part. Just because you're in a hurry don't neglect those plants that will take a long time to mature. Plant a Stewartia early on. Or a shade tree if you really want shade. They will take 20 years to mature, but procrastinating will only make you wait longer. Plant perennials that you want to colonize like asarums, or Pachysandr procumbens, or Trillium grandiflorum. Trust me, the time will pass!

Friday, October 3, 2008

I can't help myself....I really care about tree circles

I worked on the tree circles in the National Grove of State Trees today. I sprayed roundup on weeds; my original intention was to spot spray the perennial weeds inside the (relatively) clean circles, but I soon realized that wiregrass had been growing into the mulch from the surrounding turf. It is very happy when it can grow in a bare sunny area and less happy when it has to compete with cool season grasses that are almost able to overwhelm it in fall, winter, and spring. I knew that I had to stop it, so I sprayed the perimeters of the circles and that should keep them for another year.

Tree circles are an interesting concept. Everyone likes the idea of trees growing in a field of turf, but it turns out most trees aren't crazy about that situation. At least until they reach a size where their root systems can compete with the grass and their canopies can shade their roots enough to prevent extreme temperature fluctuations in the summer. Even at this point though, they are in danger of being damaged by lawn mowing equipment. A survey of the IAA (International Arborist's Association), large tree companies, and the literature, suggests that a circle at least 25 feet in diameter is appropriate for most tree species. When I began working in the Grove, the trees had either no tree circles, small tree circles, overgrown tree circles, or a combination of two and three. With a tremendous amount of help, most of the trees now have pretty good sized circles and they're mostly in pretty good condition in terms of weeds and mulch.

What I like to think of as the "corona effect" is an interesting, and bad, phenomenon that takes place with tree circles that have at some time not been properly maintained. I would guess that this includes most tree circles; certainly it includes all those in the Grove! The bare mulched areas are inviting places for seed germination and a variety of weeds take advantage of this. If they are ever allowed to go to seed themselves, when the weeds in the tree circle proper are sprayed, a corona of weeds is left in the foot or two or three of turf immediately surrounding the circles. Untreated, these weeds become a source of seed that can continuously reinfect the circles themselves.Dandelions, oxalis, violets, plantain are all common in this location. Often they don't move farther out into established turf. Killing the entire area and reseeding is obviously a possible solution, but I prefer less invasive techniques, so whenever I am spraying the circles, I make a point of killing the largest of these weeds any any that form large enough groupings to spray without hitting a lot of turf. This is important: When you spray tree circles with preemergent herbicide be certain that you spray these corona areas as well. You won't hurt the turf; it spreads by tillering not by seed. You will prevent germination of existing weed seed. That's a good thing.

Thursday, October 2, 2008

Anacostia River looking good

FONA (Friends of the National Arboretum), and the American Bonsai Association jointly sponsored a boat trip/lunch today for employees of the Arboretum. We cruised up and downriver with narration by representatives of the Anacostia Watershed Society. I think we were all amazed at how free of debris the river was. It's not free of sediment though. We learned that the channel to Bladensburg approached 40'!!??!! in depth in the 18th century. Land clearing and the inevitable erosion resulted in the deposition of a lot of silt. We were on the river at high tide and in the channel and the depthfinder read 7'! Wow.

As development has overwhelmed the river almost all of the tidal marshes have been lost to draining and filling. These marshes are a critical part of a healthy tidal river. They support a tremendous quantity of plant growth that provides the food energy that supports the entire system. The growing plants also use up dissolved nutrients and absorb and lock up or break down a variety of otherwise unpleasant chemicals that find their way into the river.The Society is working to restore/replace those areas where they can. We passed several newly contoured and planted areas, One is visible in the background of this picture.

Partly into the trip we were treated to the sight of a pair of bald eagles harassing another raptor, possibly a marsh hawk. Very cool. I often see egrets and herons from the bridge over New York Avenue in the evenings. All the bird-life isn't welcome though; the resident geese pose a huge problem with marsh restoration as they voraciously gobble up much of the newly planted material.

Tuesday, September 30, 2008

Picture this area covered with a 6-20 foot tangle of weedy trees, shrubs, and vines

We did a good project on Monday, not that they aren't all good. Working in the Holly Magnolia Collection, we cleared an area in which several large trees had fallen, through which had grown bush-honeysuckles, mulberries, ampelopsis, Japanese bittersweet, and assorted unwanted shrubs, saplings, and vines. The dense undergrowth obstructed the view in to the parking area at Kingman overlook from Hickey Hill Road. During the clean-up we discovered various pieces of physical evidence suggesting that the area was being used for nefarious purposes. Opening the view to the parking area will, we hope, discourage these kinds of activities.

We do this kind of job occasionally as part of our group project schedule, and over time we have refined our techniques, added mechanization, and greatly improved our efficiency. Where we used to cut and pull shrubs and trees, we now, if the slope allows, use the bush-hog. Ed (Boxwood ASRT) has gotten quite skilled at maneuvering it and it both cuts and chips at the same time. This means we don't have to haul the debris to the Brickyard, and we don't have to subsequently pay to have it chipped. We save time hauling, gas, wear and tear on the vehicles, wear and tear on employees (us), and are able to cover, actually uncover, a lot more ground in a day. We still have to cut up fallen trees, and the bushhog can't get to all of the undesirables, but we are now many times more efficient than we were a year ago thanks to Ed, the tractor, and the bushhog. On Monday 4.75 people (I missed 2 hours) cleared over 1/3 of an acre of badly overgrown brush. Pretty good.

Monday, September 29, 2008

These tropicals are growing on top of a bed of spring flowering natives

Though it's supposed to get up to 80 F today, fall is definitely here. Cool nights, lots of dew, earlier sunsets, driving to work in the dark, Halloween decorations. All the signs are here. Almost 2.25" of rain fell in Adelphi from the storm systems that moved through late last week and through the weekend. Regionally though, the amounts were extremely variable; one day I saw figures that showed Baltimore with 3.9", Washington with .95, and Dulles with .32". Wow. For a while it seemed as though we wouldn't even get enough to keep us from having to water this week, but Kyle (the tropical depression) came through for us and the Arboretum ended up with about an inch and a half which is enough at least for a while.

The tropicals are ecstatic. It's still warm, the humidity is up, and they have an abundance of water. Brugmannsias seem to be entering the peak of their last flush of bloom. Though they are tropicals, they seem to prefer the cooler days of autumn to the heat of summer. That's counter-intuitively true of Pelargoniums as well, though cool wet nights can cause their flowers to rot. This spring, with its consistent rainfall, turned out to have been a good season to have started grass seed. If you planted grass seed earlier this month you did the right thing, and will actually have to mow in a week or two.

Fall perennials are coming into their own: among others, Asters, Japanese Anemones, Chelones, the late-season Salvias, Tricyrtis, and varieties of what used to be called Chrysanthemum rubellum. I like all of these plants very much, and though others may be more beautiful, it's hard to imagine getting more show for your investment than you do with these perennial mums. New varieties seem to appear every year. I remember when there was only 'Clara Curtis' and 'Mary Stoker', but now there are at least a half a dozen more. Unlike the traditional garden mums, they don't need to be disbudded, or divided, or restarted, and they won't flower till October. Good plant!