What’s wrong with these pictures?

Say you’re a growing country club in a nicely-treed community, and you need to enlarge your parking lot. And perhaps you want to lower its grade. The lot has some mature oak trees in it, and they add a certain je ne sais quoi to the scene, so you decide to save the trees by keeping the grade as is around the base of their trunks. You retain the roots and soil with a mortared stone wall. Voila!



Good idea – but woops! The minimum standard for root preservation is to keep 10 inches of root mass diameter per caliper inch of tree. For these trees, that would spell at least 360-inch diameter root masses. Because the trees are so close together, their roots overlap significantly — but still, 360 inches is thirty feet of diameter. This 18-footish enclosure takes a tad too much root; the country club will almost certainly be watching these trees decline and die over the next few years (and they may well drop dead branches onto the parking lot, or cars in it, in the process).

The idea of saving a mature tree is a good one, as long as the tree’s actual requirements for continued healthy life are met. Now that we have the tools to see how large a tree’s root mass really is, it’s much easier to see how big the unimpeded area around it has to be for the tree to survive happily and thrive.

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Small-space gardening

We’ve all seen photos of grand mixed and perennials borders on old country estates (Gertrude Jekyll, Vita Sackville-West, Beatrix Farrand),

Vita Sackville-West, Sissinghurst White Garden. Photo by bestfor/Richard on Flickr.

and of sweeps of perennials, grasses and shrubs by the contemporary designer Piet Oudolf and landscape architects Wolfgang Oehme and James van Sweden.

They’re dramatic and luxurious-looking, and it’s easy to envision being right there, surrounded on all sides by space and uninterrupted swathes of glorious texture and color.
Sometimes the only space available is quite a bit smaller and more constrained. This past weekend I was walking down a suburban Boston street and found this planting, in which a narrow bed — bounded by fence on one side, driveway on the other — hosts a garden that shows off in every season.

This plant bed can't be any more than three feet wide, but there is a lot going on in it.

In this climate, plantings that flank a driveway have to be tough. Snow gets shoveled and plowed on top of them, and sometimes it’s best to stick to herbaceous perennials that will die back to the ground and be unharmed by wayward plows.
This garden has a fairly simple palette — Hydrangea, ‘The Fairy’ Roses, Korean Chrysanthemums, Sedum ‘Autumn Joy’, and a carefully pruned collection of crabapples — that works well here. Even if the hydrangeas and roses get clobbered by the plow they’re likely to recover; the sedums and chrysanthemums can be cut back to the ground, and the crabapples are trained to hug the fence, out of the way, making what could have been a winter drawback into a fine asset.
It’s refreshing to see this kind of resourcefulness in what often seem only to be incidental places on a property. This strip isn’t a place in which you’d want to (or could) lounge away the hours, but it shows how varied and texturally exciting even a small space can be.

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Air tool posts now at Taking Place In The Trees

This tree has never been bare-rooted, as far as I know (though who could say, at this point?) It lives at Elm Bank, Mass. Hort’s headquarters in Wellesley, MA, and I took these photos at last week’s air-tool workshop there.

Norway spruce at Elm Bank.

Somehow it seems that Morticia Addams should come drifting into the picture to perch on this fantastic bench, sweeping a murky gloom behind her.

For those of you still clicking on this site to see air-tool transplant posts, check out Taking Place In The Trees (www.takingplaceinthetrees.net).

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Taking Place In The Trees

Announcing a new blog! Toby and I would like to keep Taking Place a site for conversation on landscape architectural issues, and it has become clear that my woody plant posts could overwhelm this blog in way we hadn’t planned. So I’ve just started another blog, a sister to this one, called Taking Place In The Trees (www.takingplaceinthetrees.net). It’s focused on woody plant issues, and my aim is to talk about and show good photos of trees, shrubs, and innovations in their planting and care.

I began to post on it last month, with a couple of posts you may have read here. At this point, though, I’m officially launching Taking Place In The Trees as part of the Taking Place family, with posts you may not see here. I’m hoping to be able to duplicate my earlier woody plant posts from this blog on it, to get them all in one place; in the meantime, to see all those posts, click on the ‘Plants’ in the Categories section on the right side of this page, and they’ll all pop up for your reading pleasure.

I’m looking forward to showcasing and discussing more plant topics on Taking Place In The Trees, and to continuing the landscape architecture conversation that Toby and I have going on Taking Place. I hope you continue to visit both sites, and enjoy them!

Nature/culture -- the familiar combo.

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Crowding the bed

Harvard University has recently been building on Memorial Drive, along the Charles River. The site that had held a garden center (most recently, Mahoney’s, and before that, the Grower’s Market, where I sold Christmas trees one year) is now becoming a park and a graduate student dormitory. The dorm is done; the park (originally slated for a Renzo Piano museum building) is still apparently in construction.

The other day I was strolling past the parcels, and had to stop to look at a planting buffering one of the dorm’s corners. It was so rich-looking, so dense and lush, and yet it stood only a couple feet high. Fantastic! What was it?

Three feet high, with thick foliage making a bumper at the building's base.

I leaned in to take a look, and discovered that it was a mass of Fothergilla, a shrub related to Hamamelis, or Witch Hazel. (I thought at first that it was Hamamelis, wrote and posted an entire blog post on it, and then realized a few days later that I’d been mistaken. So consider this post a corrective to the other one, which I’ve now taken down.)

I figure that these are Fothergilla gardenii, or Dwarf Fothergilla, given their spacing and configuration. The plants in this mass are set on 18-24″ centers. That’s quite close even for a dwarf plant that’s recorded to grow to between three and six feet in height.

Spacing between 18 and 24 inches on center.

We have discussed plant spacing issues earlier in this blog, and have talked about the differing (and equally viable) strategies of planting close versus planting to make each plant a specimen. The jostling that plants do with each other when planted close can make for an interesting and complex arrangement.

Fothergilla gardenii is a suckering shrub that tends to form thickets; perhaps the landscape architect was aiming for a full-thicket look right from the start. It’ll be interesting to see how the planting grows, and what forms the plants can negotiate in this circumstance (will they be able to sucker where light appears not to reach the ground inside the mass?).

Michael Van Valkenburgh, landscape architect of record for this site, is known for using close plantings in his projects, and he’s generally pretty horticulturally astute. This planting represents an interesting experiment, one worth revisiting over time to see how it progresses.

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Greenery en masse

The Hamamelis planting in the last post raises the issue of mass plantings, which have long been a favorite of many landscape architects.

I remember a mass rose planting, no longer extant, in a very public location in downtown Boston. One time I went out to do a little guerilla pruning in it with an administrator from the Boston Redevelopment Authority. (Hmm. Perhaps it doesn’t really count as guerrilla pruning if the person you’re working with has the influence to make sure the cuttings are taken away by staff, much as she wanted it to seem as if she was doing the pruning sub rosa, so to speak.)

Rose thorns. Ow ow ow.

While were able to clean up the specimen roses in the planting, the mass-planted rugosa roses were another question — it was impossible for us to navigate through the thorns to remove the several years’ worth of dead wood that had accumulated. It was quite clear why they so drastically needed maintenance, and equally clear why they’d had so little. I believe that this planting has been torn out.

At Naumkeag in Stockbridge, MA, a similar deal. Fletcher Steele designed a beautiful mass Pyracantha planting on a bank below the drive, but neither I, an intern at the time, nor anyone on The Trustees of Reservations permanent staff had the asbestos legs, hands, or arms that would have made a good pruning job possible. (The common name for Pyracantha is Firethorn.)

Pyracantha has a stunning berry display, as well as some of the wickedest thorns you'll ever come across, mostly hidden under the berries and leaves (one is visible in the upper right hand corner of this photo).

The best we could do was to snip down the most obvious vertical and horizontal shoots to keep the whole thing in bounds, and just let the plants fend for themselves. I’m not sure that planting is still there, either, though in the name of historic authenticity, it may be.

However and wherever a mass planting is used, it makes sense to understand not just the look of the plant species used, but also its habit, its limitations (thorns, for instance, or a tendency toward brittleness or over-enthusiastic suckering), and the opportunities you may be closing off in using it — not least of which might be the willingness of maintenance staff to take care of it, if it’s a difficult species.

Masses can help shape space, which is what we aim to do. At the same time (perhaps I’ve said this before), it’s not a bad idea for landscape architects to get out there themselves and work with as many plants as possible in person — to do some planting, do some pruning, do some moving — to understand how these vital design elements really work in the landscape, and what it takes to keep a design looking the way you want it to look.

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Air tool seminar

Here’s a quick post to alert readers to the Massachusetts Arborists Association Special Seminar and Demonstration on air tool use. A team of four arborists — Mike Furgal, Matt Foti, Rolf Briggs, and Dave Leonard — will be showing how compressed-air tools can be used in arboricultural work (root forensics, bare-root planting, bare-root transplanting, shrub moving, etc.), and will discuss the advancements that this technology provide those working with or using woody plants in the landscape.

The seminar will be on September 10 at Elm Bank, the Massachusetts Horticultural Society’s property in Wellesley, MA — check the MAA link above for registration information. Registration is not limited to arborists, so interested landscape architects and contractors can go and see this work. I highly recommend signing up; last year’s seminar at Matt Foti’s farm, where Mike Furgal debuted the air-tool transplanting method, was really outstanding, and this year there’s bound to be even more information available and a great deal of informed and informative discussion.

One point: Bare-root transplanting, either with an air-tool or by root-washing, may never replace other methods of transplanting. But for specimen tree transplanting, where the value of an existing tree merits the effort involved, it is currently the gold standard. The number of roots retained with bare-root transplanting prevents the tremendous stress caused by other methods, and should be considered a valuable tool in the kit available to landscape architects, arborists, and contractors.

Bare-rooting allows for the moving of a tree this large in less than one day...

while preserving this much root mass.

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Here’s why to plant bare root

One reader wrote in with this comment to my last post:

“It would be no good to specify bare root unless you were thoroughly acquainted with the land – soil, ledge, utility lines, for example – and spreading roots of other trees.”

And my answer, because there’s a lot to it:

Actually, bare root is good just for the reasons you enumerate; it’s much easier to plant roots alone than it is to plant a big slug of soil encasing a plant’s roots. And landscape architects, contractors, and arborists have ways of dealing with the issues you mention.

Contractors are required to call Dig Safe (http://www.digsafe.com/) to locate underground utilities on site before any excavation begins. The mis-location of utilities has been known to happen, but excavators are (ideally) careful about how they dig and about stopping when they hit something. Accidents can and do happen, but safeguards have been worked out to minimize their occurrence. (We had a little excitement at last week’s transplanting site over a gas line — apparently DigSafe found one gas line and marked it, but didn’t realize there was another several feet away. The mini-excavator found it — without breaking it — and DigSafe was called out to mark its course immediately.)

Irrigation lines, visible in some of the photos from last week’s posts, are considered expendable/fixable during a construction project. They are relatively flimsy and they run everywhere under many projects, so it is understood that they may be broken (even a shovel can break one), and will be fixed after construction and planting have been completed.

Bare-rooting a tree or shrub for planting — regardless of the surrounding soil type — often is better for the plant than planting it in a soil root ball. When one type of soil is introduced to another, as when a clayey soil root ball is placed in a sand/loam soil, the interface between those two types of soil resists the movement of water from one to the other. That means that if a clay root ball gets watered in thoroughly, water may not move so readily into the sandy loam. What incentive does the root mass have to move beyond that interface and thus into the sandy loam? Not much. Opening up a root ball and mixing some of its clay with the surrounding soil in the wall of the hole will help, but still — with a bare-root plant that issue is a non-issue. Even with a poor soil, it’s easy to mix some planting loam in with the surrounding soil (again, you want to mix, not simply dump a pile that will give you that same resistant interface) and plant the bare-root tree or shrub in the mix; doing so will make it possible for the plant’s roots to reach as far as they have to for the moisture they need.

it is a tendency, unfortunately, of many planting crews (especially on very large jobs where speed is of the essence and there may be little job training for laborers) simply to push the burlap on a root ball down just below the surface, or in some instances to leave it tied in place before backfilling. Natural burlap eventually will rot, but it can take years, especially given the subsurface soil environment, where the burlap is protected from the atmospheric oxygen and UV light that breaks it down so readily in the nursery. In the meantime, that burlap constrains root extension into the surrounding soil, and can contribute to the roots turning back in to the root ball, which affects the growth of the whole tree. So — another reason bare-root is a good approach: no burlap to fool around with and to constrain root growth.

As for ledge: You’re unlikely to know the location and profile of subsurface ledge until you start digging. That’s just the way it is. Again, though, the presence of high ledge (that is, ledge just below the soil surface) argues for using a bare-root planting method. Since tree roots typically live in the top 12″ of soil (sometimes 18″, and sometimes deeper, given the plant genus and the depth of good soil), and tree root balls can be as deep as 36″, planting a tree with soil around its roots means that you have to accommodate that root ball. Sometimes you can slice off its bottom with little ill effect on the roots. Sometimes you can’t. With a bare-root plant, you don’t have to jimmy around so much with adjusting the height of the root ball. Certainly, you’ll have to be sure you have adequate soil depth to plant the roots themselves (spreading them out radially, as they typically need to grow), but bare-root planting gives you much more flexibility in this regard.

OK. That’s it for this post, because I have to hit today’s design deadline, and this was a digression from working on it. Sorry about the lack of photos on this post; next one will have a set of really good ones, courtesy of Matt Foti.

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Bare-root comments

For those of you checking out this blog for the air-tool transplanting posts, you may find it helpful to read the comments on those posts for more information…And if you’re a landscape architect or arborist and have observations, questions, comments, please feel free to submit them in the comment box as well. This technology and its applications are so new that the more good information gets exchanged, the better.

Lots of root mass. Irrigation lines run through it; they are cut during the trenching process, and then pulled out in feet-long lengths once enough soil has been blown away from the roots.

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Air tool excavation — London Planes

The project showcased in the last post continued this week, with the bare-root transplanting of five London Plane trees (Platanus x acerifolia) and a mature crabapple. Again, Matthew R. Foti Landscape and Tree Service was the prime arborist on this site in a Boston suburb — but this week the Foti crew was joined by Mike Furgal, who was the first arborist to use the air tool for bare-rooting trees in this way.

Mike has been doing this work a bit over five years, and his expertise was the basis for the bare-root workshop sponsored by the Massachusetts Arborists Association and hosted by Matt last August. Neither arborist had moved this many trees of this size — the London Planes ranged from 11 inches dbh to 13″ dbh — and in teaming up they brought all their knowledge to bear to the challenges of this particular project. (The homeowner figured she had hired the A team, given the pair’s depth of knowledge and breadth of experience.)

I took a lot of photos during the first day, and returned today to shoot more. My colleague Bruce Jones and I also shot extensive videotape of the process, which is currently in editing, and will explain the sequence of bare-root transplanting using compressed air (watch this blog for word that it’s done and available).

To avoid computer-use burnout (mine), I’m posting one batch of photos today, and will add another post with more in a few days. I promise, this first batch of images will be plenty to digest for a while….

The site before the five London Planes get moved. The first tree to be excavated and moved is the one furthest from the camera, just to the right of the white trailer. These trees flanked a driveway; in this photo the driveway asphalt has been taken up and the gravel base has been partially removed. Trees are located 3-4 feet from the drive edge.

The mini excavator has dug a partial trench; the trench must be dug in sections, or it would be too difficult to reach in and haul out the blown soil. A climber is in the tree, tying in lines to be used later during transport.

Bare-rooting has begun, and one pigtail of roots is already tied to the tree's trunk. The tree did not extend any roots into the gravel driveway base, so it only has 3-4 feet of root mass on that side. It did extend its roots out parallel to the driveway, and radially out into the lawn. A good depth of soil also let it sink its roots quite deep -- 2-3 feet -- into the ground. Mike Furgal is in the green jumpsuit and facemask.

Pigtailed roots, and short roots along the driveway edge.

Good deep soil, good deep roots -- everywhere but at the gravel.

Lots of activity at the tree: two air-tool excavators, an mini excavator digging the trench, a Bobcat taking soil away, and Matt Foti assessing progress.

Blowing out soil, getting closer to the move.

Padding the trunk with layers of burlap for the move.

Giant forks have been run under the tree, and the loader is getting ready to lift it. Four taglines are visible in this shot; they won't prevent the tree from falling, but help indicate how it is balanced during the move.

Lifting and backing, slowly and very carefully.

A pause for the forks to be positioned more firmly.

Big machine, bigger tree. The root plate on this tree extended about 18 feet across at its maximum width. Transporting a large, upright live tree is a slow-speed operation.

Compare this root plate to that of a B&B tree, or a tree-spaded one (though this tree is too large for a tree spade), and it's clear what an advance this technology promises to be in benefiting the health of trees to be transplanted. The tree's energy reserves are largely stored in the roots; save the roots, reduce stress on the tree, and speed re-establishment after planting.

The tree, post-planting. The arborists assessed how deep the root mass was and how it was formed, and dug the planting hole to accommodate, roughly, its form. Once the tree is placed in the hole, the roots are spread out radially by hand, and loam shovelled in around, under, and over them. Watering starts during the digging process, once the tree has been levelled, so that a loam slurry anchors the root plate and tree to its new site. A well is formed to retain moisture and more water is added.

Two to four inches of mulch is added around the tree, and kept away from the trunk.

Minor pruning to fix a lamppost-branch conflict.

The transplanted tree seven hours later, in its new home.

Matthew R. Foti Landscape and Tree Service, Lexington, MA – lead arborist
Furgal Tree and Landscape, Northborough, MA – consulting arborist
Robert Hanss Inc. Landscape Construction — landscape contractor
Reed Hilderbrand — landscape architects (Chris Moyles, project manager)

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