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Posts Tagged ‘root flare’

Contractors, arborists, and landscape architects in Massachusetts would do well to check out the Ecological Landscaping Association’s September events list.  The ELA is offering a number of really good workshops, on topics ranging from Boston-area restoration projects to the use of fire in landscape management, as well as a two-part, two-day workshop on root issues.  

One day of the root work will focus on soils(f you’ve read any of this blog, or Taking Place In The Trees, you’ll know that I’m interested in roots.)  In the air tool workshop, entitled At The Root: Air Tools Workshop, Rolf Briggs and Matt Foti will be talking about using air to work in the root zone, to decompact soils, to transplant trees and shrubs and also about how to plant nursery-grown stock properly.  

Matt and Rolf have done a similar workshop for the Mass. Arborists Association in the past, and Matt holds an annual workshop on proper planting techniques.  Being able to see what a root system looks like is eye-opening.  Learning — not just from written specs or a generic tree-planting detail — how a tree or shrub should be planted is essential, and well worth the price of admission.  I have been to at least three of these workshops, and learn something new at each one, and so can say that this workshop is one every landscape architect who designs plantings, and every contractor who sells plantings should attend.

Michael waters in a hemlock whose root flare has been excavated with air.

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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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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.

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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To continue the story from the previous post (check out the photos on that one):

Wednesday, I had to visit Cavicchio’s Greenhouses to tag a tree. Carl and I arranged to meet there, and Carl called to see if Jake Cavicchio could meet us at the little pin oak. We bumped down a back road to the base of a slope, and recognized the tree immediately. It had some deadwood, but had leafed out nicely and seemed to be growing well.

Jake remarked on the deadwood — he said that it had all been there last year, and that this year no more seemed to have developed.

The day after the root-washing, Cavicchio’s had planted in three other pin oaks, similarly root-bound, in the same area. Those three were planted conventionally, their root balls holding the same red clay that had been washed out of the first tree.

The most noticeable difference between the first, root-washed tree and its companions was that the three conventionally planted trees were showing signs of current stress, while the first tree looked fine. Each of the three other trees had foliage sprouting from its trunk, a symptom of stress and an indication that the tree is trying to counteract decline. On the other hand, each of the trees also had similar top growth to the first tree.

It is probably too early to tell what the future will hold for any of these trees — regardless of planting method, the fact that all the trees are now planted out boosts the possibility that they will survive. It seems entirely likely, though, that the tree whose roots were freed from the dense clay soil ball will now encounter less struggle to reestablish a vigorous root system, and that reduced stress for it will mean a healthier prognosis than for the other trees. Take a look at these photos.

Jake Cavicchio and Carl Cathcart with the root-washed pin oak planted last October

Jake Cavicchio and Carl Cathcart with the root-washed pin oak planted last October


Jake with the pin oak he root-washed

Jake Cavicchio with the pin oak he root-washed


Well-structured root flare, at the right grade

Well-structured root flare, at the right grade


Conventionally planted pin oak, planted at the same time as the first tree, showing signs of stress

Conventionally planted pin oak, planted at the same time as the first tree, showing signs of stress


Adventitious buds along the trunk have leafed out, indicating that this conventionally planted oak (which had been balled and burlapped for two years and was unsaleable) is under stress

Adventitious buds along the trunk have leafed out, indicating that this conventionally planted oak (which had been balled and burlapped for two years and was unsaleable) is under stress

Owner: Cavicchio’s Greenhouses, Inc., Sudbury, MA
Arborist: Carl Cathcart, MCA
Tree mover: Jake Cavicchio
Scale figures: Carl Cathcart, Jake Cavicchio

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If you have read the last post but are new to this blog you might take a look at this link; it’s my Lawn and Landscape article on the bare-root transplant workshop conducted last summer by arborists Mike Furgal (who developed the method of transplanting specimen trees bare-root, using an air spade) and Matt Foti (who hosted the workshop and has gone on to use the bare-root air spade technique on every transplant project he can).

The article describes the workshop’s successful transplanting of several trees on a hot August day, and lays out some of the nuts and bolts of how the work is done. Mike and Matt’s workshop charged up every one of the 100 or so attendees. As a result, many Massachusetts arborists and contractors are turning to the air spade to save and transplant specimen trees. I hope that the previous post (“Air Spade in Action”) helps to expand our understanding of some additional uses of this tool.

(And no, I am in no way affiliated with the company that manufactures either the Air Spade or the Air Knife, or any other kind of tool.)

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This past winter I developed plans for a couple of areas on the property belonging to my longest-standing and wonderfully enthusiastic clients, L. and A. on the North Shore. They have a lovely place on a rocky cliff overlooking Nahant Bay, and they enjoy making it even more beautiful and comfortable each year. They are both artists, and both appreciate art in two and three dimensions: L. gardens and sculpts; A. is a talented photographer.

L. and A. had asked me to figure out how to screen out views of two neighbors from their house, and to develop plans in the two areas that would work with the extensive mature plantings already in place. I drew up plans that would bring a few new plants in, as well as reuse a number of plants already onsite. L. and A. liked the ideas, and we scheduled a date to move ahead.

Leahy Landscaping of Lynn carried out the work of digging and moving the plants; the crew, led by Anibal Marita, was excellent. At my request, and under the supervision of Marc Bolcome, Leahy’s arborist, they used a compressed-air tool on the project; we were working in a heavily planted area and I wanted to disturb or lose as few roots as possible.

The plan: Remove a 32′ long, 7′ high holly (Ilex ‘China Girl’) hedge from the edge of a residential drive court, reusing some of the plants for screening at the front property line, and install a collection of transplanted shrubs, a new Japanese maple, and some low Green Wave yews where the holly had been. Transplant most of the hollies to provide a 22′ long screen at the front property line, and use the rest at another location onsite.

Proposed methods: Hand-dig the holly. To avoid further stressing the three aging red pines under which some of the hollies were to be transplanted, excavate the transplant site with an air tool. Hand-dig the rest of the plants.

Actual methods: Hand-dug the holly, then blew out the root balls to loosen the nursery soil at their cores. Discovered that the wire baskets had not been removed at the original planting, removed those, and loosened the remaining soil, leaving roots intact. Removing the soil allowed the plants to fit in shallower-depth holes, which was helpful on a site with a lot of existing tree roots and drainage pipes. Removing the wire baskets will allow the hollies’ roots (and crowns) to grow unimpeded in their new locations.

Excavated under the pines with the air tool, and removed existing shrubs there also with the air tool, leaving all roots, including masses of feeder roots, intact.

Unwrapped the Japanese maple root ball, removed the wire basket and burlap, and removed/loosened the soil with the air tool.

Removing a girdling root from the Japanese maple.  Note the root-ball soil line, four inches up the tree's trunk from the base of the trunk flare.

Removing a girdling root from the Japanese maple. Note the root-ball soil line, four inches up the tree's trunk from the base of the trunk flare.

With a mini-claw mattock, pulled soil away from the trunk flare; soil had been piled 4″ up the trunk, concealing a girdling root and the flare itself. Marc Bolcome chiseled away the girdling root and made sure the flare was correctly exposed before laborers backfilled and watered in the root ball.

Removed the red clay soil encasing the nursery root ball of a rhododendron that had been planted onsite several years ago, but that had struggled for those years.

Breaking up the clay soil in the root ball of a rhododendron that had been planted under these pines a few years back.

With the concrete-like soil mostly gone, the plant should finally have a chance to spend its energy growing, rather than trying to break through that clay cast.

Cleared ground cover by hand in front of a row of mature Taxus trees,

Holes for holly transplants were dug by air tool, to minimize disturbance to the roots of the treeform yew hedge behind the plywood.

Holes for holly transplants were dug by air tool, to minimize disturbance to the roots of the treeform yew hedge behind the plywood.

then excavated transplant holes with the air tool — again, to keep from disturbing roots of the existing yews — and transplanted more of the holly here.

The original plan, which also included the planting of six large clump bamboos and the moving of several broadleaf evergreen and herbaceous plants, was scheduled to take perhaps two days.

The hollies changed everything, though. They were enormous: planted eight or nine years ago at 3′ on center, they opened out to seven to eight feet in width.

One holly, trussed for moving.  Ten of these plants had been placed on 3' centers to make a hedge; when freed from the hedge, each one opened out to cover at least seven feet in breadth.

One holly, trussed for moving. Ten of these plants had been placed on 3' centers to make a hedge; when freed from the hedge, each one opened out to cover at least seven feet in breadth.

There was no way we could fit them all where we had intended; they would have taken up more than seventy feet if we had placed them side by side!

Hand-dug holly that has been bare-rooted being prepared for transplant.  Notice the clumps of hard, heavy soil from its original root ball lying around it; the wire basket is lying off to the left.

Hand-dug holly that has been bare-rooted being prepared for transplant. Notice the clumps of hard, heavy soil from its original root ball lying around it; the wire basket is lying off to the left.

The trussed holly, now untied and moved to the planting bed, is at the back right of the photo.  Liberated from the crush of a too-tight hedge planting, it has opened out to cover almost nine feet of fence.

The trussed holly, now untied and moved to the planting bed, is at the back right of the photo. Liberated from the crush of a too-tight hedge planting, it has opened out to cover almost nine feet of fence.

It took a while to figure out where to put them, and then more time preparing those new locations to receive them. We ended up placing them — ten from the hedge, plus a shorter male plant — at various points around the property’s edge, where they do a magnificent job of screening out the neighbors.

We also used the air tool to excavate under some mature and very stressed red pines. Removing the pines wasn’t an option, so to minimize any added stress, we blew out a planting trench between the pine trunks and the fence, exposing but not disturbing the pines’ roots. We roughed up the bamboo roots, taken from their five- and seven-gallon pots, and set them in the trench before backfilling and watering the area.

All told, accomplishing the work took a full three days.

Lessons learned:

1. An compressed-air tool is a great tool for any kind of planting work. We tested its capabilities, and found it invaluable for working under trees, for bare-rooting new plants, for excavating existing shrubs, and for removing that dreadful red clay soil from the 4′ rhododendron. We used it to investigate suspicious root issues — that concrete-like slug encasing the rhody’s root mass, the hollies’ wire baskets, the Japanese maple’s buried root flare and girdling root — and when it wasn’t being used on the transplanting operation, we used it to give a little breathing room to the root flare of a river birch planted on site a few years ago.

On this particular site, which has been intensively gardened for decades, the soil is beautifully dark and rock-free. The air tool had no difficulty blowing it out of planting holes. Even with a rockier soil, an air tool has enough pressure (90 psig in this case) that bare-rooting shrubs takes a relatively short time. A laborer team can generally dig a 4-5′ broadleaf evergreen shrub in minutes. An air tool can do it as quickly or in a few more minutes, depending on soil type — but the amount of root mass saved makes the air tool by far the preferred method, horticulturally.

2. Plywood screens work beautifully to confine the overspray of soil from the spading site. For bare-rooting the already-dug hollies, the landscapers figured out that they could lift each plant into the back of their high-sided truck and spade off the root soil there, which kept the soil contained and the site clean.

3. At a minimum, workers using the air tool or helping with the bare-rooting should wear goggles and a face mask; very fine particles of soil spray everywhere at high pressure, and eyes and lungs should be protected. In rocky or sandy soil, the hazard is greater, and long sleeves and protective visored helmets are a good idea. The compressor is loud, too — ear protection should be used as well.

4. Never plant China Girl hollies that close together. They have a lush and luxuriant round form, and are determined to grow to that form (shrubs will push to grow into their particular habits — with some, you can push back by hedging them, but it makes sense to pick a variety whose natural habit lends itself to hedge form). Ten hollies had been planted at 3\’ o.c. to make a hedge; when removed from hedge configuration, the plants spread to between seven and nine feet in breadth. These plants now make a contribution to the landscape that they couldn’t in hedge form. L. couldn’t remember if the original plan, done by another LA, had called for China Girls or for some other holly, and wondered if the contractor might have substituted China Girls for something else. We’ll never know — but we’ll know what to avoid in future.

5. It made a ton of sense to excavate the bamboo’s planting trench with compressed air; with air, the pines’ roots remained intact and we could spread the bamboo roots out easily within the broader rooting area we had exposed.

Conclusion: The planting techniques were first-rate, the plants looked happy, the place looked great. L. and A. are delighted with the results (I know I’ve succeeded when I’ve pleased their artists’ eyes), and Leahy is moving on to do other air tool projects, knowing how well the technique works in a number of different situations. Now we’ll all be watching to see how everything grows; I’m betting they will all thrive.

Company: Leahy Landscaping of Lynn, MA
Leahy Project Manager: Aisha Lord
Leahy Arborist: Marc Bolcome, MCA
Leahy Foreman: Anibal Marita

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To avoid lengthening that last post any more, I’m posting a couple more photos of trees with buried root flares here. These are pear trees; in the first photo, you can see moss growing on the trunk just above what had been the root ball grade when the tree was planted.

Note the wound behind the ruler, and the adventitious shoot coming off the trunk -- one a reason for stress, the other a sign of it

Note the wound behind the ruler, and the adventitious shoot coming off the trunk -- one a reason for stress, the other a sign of it

Beside the fact that a tree with a buried root flare is a stressed tree, the extra soil heaped against the bark can conceal injuries or root problems that would otherwise be evident. You can see the edge of a wound behind the ruler, which had been covered by soil at planting. The adventitious shoot coming out of the trunk just above finish grade is also a sign of stress.

This next photo shows two pear trees, planted at the same time and at the same size, two years before this photo was taken. The tree on the left is the one in the previous photo; the tree on the right had minimal root flare burial. Growth of the tree on the left has been set back by several seasons.
pear-trees1

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It just dawned on me that I haven’t written yet about something that I’ve seen more and more — on virtually all my projects for the last several years, in fact — with new trees being planted in the landscape.  It’s this:  

Trees coming in from the growers these days (at least here on the East Coast) are often burlapped too deep to begin with. Cultivation practices in the growing nurseries have changed in the last several years; when tilling machinery runs up and down the rows, they flip loose soil toward the young trees’ bases, where it piles against their trunks.  The soil is not raked or pulled away, unfortunately, and accumulates with each pass of the cultivating machinery.

When the trees are dug, they are burlapped and basketed to make handling easier, and the picking up and moving of the trees can squnch soil even more snugly around the trunks.  By the time a tree reaches its site, it may have 4-8″ of soil above its root flare.  If it has been in the nursery long enough, it may have started to grow a secondary root system into the extra soil; the root flare needs oxygen, and feeder roots that are too deep stress a tree.

This sugar maple was planted six inches too deep

This sugar maple was planted six inches too deep; an arborist excavated it one year later


It’s really important, in the planting process, to check the root flare and see that it is in the proper relation to actual finish grade, and if it isn’t, to pull away (gently, please — that bark may be tender!) the extra soil and expose the root flare.  If that new little wiry root system has started to grow, it can be cleanly cut away at this point.

These days, I see lots of trees planted too deeply.  I figure that it’s because the contractor assumes that the top of the root ball is the actual finish grade required by a tree.  A stressed or ailing tree may sometimes be saved by the simple act of excavating that extra soil, and letting the root flare breathe.  (When a young tree has been in the ground on site for a year or more and isn’t settling in well — has small leaves, looks chlorotic, has sparse foliage — the first thing to check is the root flare relationship to finish grade.)

The maple on the left was planted at the proper depth; the two maples on the right were buried

The maple on the left was planted at the proper depth; the two maples on the right were buried

Arborists know about this problem; they’re often called to a site to find out why one or more new trees is doing poorly, and often they find that correcting the soil depth takes care of the issue.   Some contractors know about this problem, but typically their laborers don’t, and it takes time and focus to teach them and have them make the correction with every tree.  The landscape architect’s insistence on excavating that root flare can make the difference between a tree that settles in and thrives and one that struggles and develops more problems.

Ideally we could team with arborists, with nurseries,  and with other landscape architects to get word to the growers that changes to their cultivation practices could eliminate the problem of trees showing up on site buried.  In the meantime, making contractors aware of the issue — and being sure they address it during planting — can help insure the good health of our tree plantings, and the integrity of our designs.

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