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Archive for the ‘Gristmill’ Category

Last week at New England Grows, while Toby was manning the table for the Ecological Landscape Alliance (its shiny new name hasn’t made it onto the website yet, but the ELA is an outstanding organization, and so is their material), he struck up a conversation with Jeff Ott, owner of Northeast Shade Tree in Portsmouth, New Hampshire. Jeff told him about a workshop he’ll be giving on March 6 for landscape professionals; it’s called “Tree School for Landscapers; The Built Landscape From An Arborist’s Perspective”.

The Old Elm on Boston Common, 1876 Courtesy Boston Public Library via Flickr; Creative Commons License:http://creativecommons.org/licenses/by-nc-nd/2.0/deed.en

The Old Elm on Boston Common, 1876
Courtesy Boston Public Library via Flickr; Creative Commons License: http://creativecommons.org/licenses/by-nc-nd/2.0/deed.en

Jeff, who has been an arborist for the last 36 years, had the great good fortune to work with Alex Shigo — probably the most influential tree researcher of the 20th century. Recognizing that more intellectual cross-pollination between arborists and other landscape professionals would benefit the landscapes on which we all work, Jeff decided to put together this workshop. The timing is good, before the spring planting and construction season gets rolling, so I’m aiming to go, and hope that other landscape architects will seize the opportunity as well.

Here’s the Tree School announcement.  Don’t be alarmed about the absence of an address:  you send your registration form and check ($75) to:

166 Clinton Street, Portsmouth, NH  03801

And here’s the Tree School Agenda, which outlines what will be happening through the day.  Contact Jeff if you have further questions; he can be reached at jottphc@gmail.com, or by phone at 603-463-7512.

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In my work doing residential landscape architecture, I have encountered a number of instances where someone has bought a house on a sloping piece of land, getting what seems to be a steal. Usually, the buyer/client first tackles work on the house, revising its interior, and sometimes its exterior, to make it just as he/she wants it to be. House modifications can take years. When the house update is done, the homeowner turns his/her attention to the landscape. Most people want as much usable outdoor space as possible: a patio is a pleasant place to sit, a big, level lawn lets kids play comfortably and within sight, and walking, driving, swimming, or playing sports are all easier on flat surfaces. And it’s when the owner of a sloping site wants to enlarge their usable domain that it becomes clear why the dream house was such a bargain.

Why? Because slopes are expensive to unslope.

For people to use the land immediately around their house with any degree of comfort, it’s necessary to make level areas. A patio typically has a cross-pitch or slope of not more than 2% (just enough to drain water), and a lawn that slopes no more than 5 or 6 percent is best for active kids to organize and play games on. When a house is built on really noticeably sloping ground, the grade can measure anywhere from 8 to 15 percent, or more.

Sometimes earthen banks can hold up a level area; sometimes strategically placed boulders can do the job; often large retaining walls are necessary. Where surface area is scant, retaining walls may be the most efficient way to hold land level. Walls tend to be costly.

To start from a different point: A couple of years ago, I had the good fortune to visit a friend in Konstanz, Germany. While there, we took a number of side trips into Switzerland. We punctuated our train trip to Appenzell, Switzerland (home of many cows and of Appenzeller cheese, a famously stinky but delicious local specialty) with a visit to St. Gallen, home of a UNESCO World Heritage site, the Library of the Abbey of St. Gall.

St. Gallen, Switzerland, from the air. The medieval walled city core is clearly visible among the more regular fabric of later-built streets and buildings. The Abbey and its World Heritage Site Bibliothek can be seen at about four o'clock in the walled part of the city.

The Bibliotek (Library) was closed when we arrived. We were ready to take a rest anyway, so found a spot on the spacious and sunny courtyard lawn and got out a picnic lunch. The day was bright and only slightly cool; though cars puttered by outside the court and a bell nearby clanged the hour and several other people sat on the grass and on nearby benches, the courtyard felt extraordinarily tranquil and pleasant. We munched and chatted, and I tried to put my finger on what made the courtyard feel so different from the surrounding area.

Look closer at the Abbey and its grounds. It takes up a large area within the walled city, and though the surrounding land slopes to the northwest, (that is, toward the photo's top left corner), the huge Abbey courtyard is almost perfectly level.

I had been thinking about the slope/cost issue for a quite some time, and it sprang to mind again in that peaceful abbey close. From the railroad station in the valley bottom, we had climbed winding medieval city streets to get to the Abbey; the walled city around the Abbey sat considerably higher than the station itself. Outside the three-sided Abbey complex, streets bent and sloped against the thick walls of the Roman Catholic enclave. Inside, green grass carpeted an utterly level quadrangle, muffling sound and lying like a tablecloth on a tabletop

Outside the Abbey walls is an orderly but dense fabric of masonry buildings and narrow streets that wind up and down the hilly terrain. Inside the Abbey walls, the utterly level and open ground of this tranquil courtyard puts on display the power and wealth of the Church that built it. Photo by kind courtesy of Galen Frysinger, at http://www.galenfrysinger.com/

In this Swiss city, slope is a fact of life. Buildings themselves do double duty as retaining walls; the back door of a house here can easily be situated a full floor above the front door. The city fabric is tightly woven, to conserve energy and again, because amending long sloping frontages can be expensive. Most homes are built cheek by jowl, with little or no space between houses.

The Church was and is a wealthy and powerful homeowner/landowner, as evidenced by its leveling of a sizable piece of the town’s steep foothill to make a vast piece usable ground. The fact that the courtyard lies in the middle of this densely woven city, and that it is given over to luxurious lawn sends a quiet but clear message of power and wealth. While the elegant and extremely solid buildings convey that message, the carving out of level outdoor space speaks just as definitively about the ability of this particular institution to make unlevelled places plain.

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That last post made a good point — sometimes the leftovers in a landscape can be used as a feature in and of itself — but I much prefer the photo here. This hemlock is very much alive, and lives outside of Boston on private property. Carl Cathcart, Consulting Arborist, took me to see this wonderful tree last July, and you can see more photos of and information on the tree at Taking Place in the Trees.

To get an idea of the scale of this tree, look just to the right of the tree's center; Carl Cathcart is standing on the ground under the tree's canopy, and his legs are just visible.

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The other day I was on Beacon Hill and spotted this mostly dead hemlock tree, completely swathed in Boston ivy:

Though this hemlock tree on Beacon Hill is dead, its stripped-down structure maintains usefulness, as Boston ivy covers it entirely with foliage.

Perhaps the owners were simply neglecting their courtyard garden, but I like to think that they saw the mature tree’s size as an asset to the place, and decided to use the deadwood as an armature for another plant, and to use the resulting ‘hybrid’ as a garden element.

I have seen this strategy used with other trees; an ancient, mostly dead apple through which a vigorous rose climbs and blooms, tiny dead crabapple that hosts a clematis vine, and a couple of thriving Norway maples through whose canopies wind equally thriving wisteria vines.

We see bittersweet and poison ivy taking advantage of the height and sun exposure offered by trees; why not use that principle and foster the growth of ornamental vines over dead trees, or, as in the case of the Norway maples and wisteria, let one aggressive species provide a platform for another aggressive species?

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It has been a while since I’ve written about root flares. I got some photos from my friend Carl Cathcart the other day, showcasing the excavation of a hemlock root flare. This tree is one of a hedge of 7-8′ tall hemlocks planted two years ago. Its owner had noticed that while the hedge wasn’t failing, it wasn’t exactly thriving, either. He called Carl, a Consulting Arborist, in to inspect the situation.

Carl zeroed in immediately on the base of the tree, and with a little hand excavation discovered that the hemlocks were sitting at least four inches too deep in their root balls. It has been customary for years to plant balled and burlapped trees so that the top of their root balls sits at or slightly above the finish grade around them. Cultivation practices in the growers’ nurseries have changed since that technique became the standard, though, and now it is necessary to check each root ball to make sure that root ball soil is not covering a tree’s root flare. A buried root flare — whether it is buried with root ball soil, compost, or an excess of mulch post-planting — spells trouble for a woody plant, and can be the cause of a tree’s failure to thrive. Small leaves, shorter-than-normal annual twig extension, and thin foliage can all be symptoms of a buried root flare. Root flares are not roots and are not adapted to life under the soil surface; they are part of the tree’s aboveground trunk, and typically need to be exposed to the air.

The in-field solution to this problem (should the excess soil not be removed in the nursery) is to excavate the root flare onsite during project planting. This task should be done before the tree is planted, so that the flare is planted at the correct grade; unfortunately, many contractors are not even aware of the issue, and will not have included time for root excavation in their bid. Here’s where landscape architects can make a major difference in the longevity of their project’s woody plants, and where contractors can distinguish themselves from the competition; LAs aware of the need to excavate root flares should include that requirement in their bid sheets for contractors, and contractors aware of that need (whether they are in a bid situation or not) can use this task, and the benefits it brings to the planted landscape, as a compelling selling point.

When root flare excavation doesn’t take place when the plants go in the ground, the signs of tree stress will likely show up within a year or two. At that point, hand excavation is still possible, but air-tool excavation usually will be more efficient.

When Carl identified the problem, he advised the homeowner to have air-tool excavation done. Matt Foti of Matthew R. Foti Tree and Landscape sent over a crew to carry out the work; Carl’s photos illustrate this post-planting process nicely.

The arborist has tied up the hemlock's branches for easier access in to the root ball. In this photo some of the soil has been blown away already.


A compressed air tool blows off the root mass. Just visible behind the tree is a plywood barrier that helps keep airborne soil from covering the surrounding plants.

The root flare has been uncovered; note the soil line about four inches up from the root mass. When you see side branches at, just above, or even emerging from below the soil level you can suspect a buried root flare. Carefully scraping away soil at the tree's trunk will indicate if further excavation is necessary. Now that the root flare is exposed, it is possible to see the girdling root that has formed on the trunk's left side.


The girdling root has been cut off, preventing any further vascular constriction in the root coming off the trunk and heading toward the photo's lower left corner.


With the root flare exposed and girdling roots removed, planting soil is blown or shoveled back into the excavated area at the correct grade.


The last step, before untying the branches, is to water the excavated area thoroughly, to rehydrate roots and to eliminate any air pockets in the root mass.

Project site: Private Residence, Sudbury, MA

Consulting Arborist: Carl Cathcart, A Plant Healthcare Consultant
Arborist for root flare excavation: Matthew R. Foti Landscape and Tree Service, Inc.

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About ten years ago, I noticed a mild fad rev up in the gardening world; all the garden centers around here started carrying Salix integra ‘Hakuro Nishiki’, usually trained into standard form with a 3-4′ high stem and a pompom of foliage at top. Hakuro Nishiki, also known as Dappled Willow, is a fast-growing, twiggy large shrub/small tree with variegated white and light green to pink leaves, and it lights up a garden with its foliage, which is profuse and almost aggressively healthy-looking.

I’m fond of these plants, though they certainly need to be placed with care. They like full sun, but can deal with some shade. Because they grow so vigorously, it’s a good idea to commit to pruning them every year or so, to keep them in bounds. Actually, I can see how sculpting them in various ways each year might be an interesting exercise — not something you’d want to do with most plants, but this one seems malleable enough to allow some experimentation.

I have written earlier about L. and A., my excellent clients on the North Shore, who enjoy developing and fostering their landscape. Several years ago L. bought a Dappled Willow for her perennial garden. It’s not a standard form; instead, she’s keeping it pruned low, to keep it in scale with other elements in the garden. Here’s a photo of it in leaf:

This plant is about thirty inches high and wide, and is kept as a mounded shrub with pruning.

And here’s a photo of how L. prunes it to keep it contained to this form:

Every year L. cuts this Dappled Willow back hard, to keep its vigorous growth contained in a form that works for her perennial garden.

I have wondered what these plants look like unpruned, and last week got to see one. If the willow in L.’s garden looks like a contained explosion, this one looks as if the top blew off the container:

Perhaps the owner of this plant didn't realize what level of attention Hakuro Nishiki was going to require annually.

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Don’t you love this photo? Toby Wolf took it at the Crane Reservation in Ipswich, a property of The Trustees of Reservations. He said that for him it has the quality of an oil painting; I agree completely. It has that same dark/light/dark sequence, that same frame/focal point/background flavor as a painting by an Italian Renaissance painter.

At the Crane Reservation, Toby writes, “It looks like The Trustees have deliberately maintained the opening to the view, and that the late-afternoon light, raking across the marshes and the bark of the trees, is what makes it work. I like the light on the ground-layer plants.”

The whole ravishing photo.

Here’s an example of landscape management supporting a design intention. Sometimes we design places with stone, wood, earth, metal, and plants; sometimes we design views, and tweak a visitor’s perception of a place by what we leave in, what we remove, and how we frame and focus what they see. Obviously, a photograph can be manipulated to do these things, but sometimes a photograph simply records a perception that has been shaped by others, as The Trustees have apparently shaped the Crane Reservation view.

A view framed by dark elements, a view into a light space, a view toward water, a view toward curves — what a pleasing combination. I want to take a bite out of this photo.

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