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Posts Tagged ‘Bare-root transplanting’

In the fall of 2008 Carl Cathcart persuaded Cavicchio’s Greenhouses to wash the roots on a stressed B&B Quercus rubra (Red Oak), and to plant it in a spot where it might be able to settle in.  Carl sent me photos of the root-washing process, which I posted on Taking Place last summer.  He and I then drove to Sudbury to see the tree, and to check out the three Red Oaks in similar condition that Cavicchio’s had planted conventionally, to see how they would progress in relation to the root-washed oak.

Photos of all the planted-out trees are on Taking Place, and because there are so many of them I’m simply posting the links to those posts here.  To see the photos and read about the root-washing experiment, click here first, and then click here.

The summary:  in mid-July, the bare-rooted tree looked best of all four trees.  It had some dead wood, but nothing that hadn’t been on the tree the previous autumn, and it had good foliage color and density, if the foliage itself was a bit small.  By comparison, the other three trees looked as if they were struggling: each tree had sprouted out new shoots along its trunk, often a sign of a tree in decline; foliage was small, and there was lots of deadwood in each tree.  It’s not a scientifically rigorous experiment, but one worth following over the next few years, to see how the trees progress.

Leaning into the root ball.  Lower water pressure may be a bit easier for those tiny feeder roots, but high pressure makes getting the hard clay soil off a faster process.  It's not clear yet how feeder root regrowth is affected by this kind of treatment, whether the pressure comes from air or water.  Early reactions seem promising, but it may be several years before a re-examination of the roots shows how risks and benefits balance..

Leaning into the root ball. Lower water pressure may be a bit easier for those tiny feeder roots, but high pressure makes getting the hard clay soil off a faster process. It's not clear yet how feeder root regrowth is affected by this kind of treatment, whether the pressure comes from air or water. Early reactions seem promising, but it may be several years before a re-examination of the roots shows how risks and benefits balance..

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If you’ve been interested in the issues on this blog, you might well want to look into another blog, this one written by four horticulture professors.  They’re each based somewhere different — Washington State, Virginia, Michigan, and Minnesota — and they write with humor and expertise about plants and plant issues.  The Garden Professors started posting in July 2009.  They talk about root-washing, propagation, nursery practices, soil contaminants, slugs, rubber mulch — you name it, they’re addressing it.  A recent post highlighted the air-tool transplant of a beautiful 10″ caliper weeping white pine by a Michigan State University Nursery Management class and the MSU arborist. — take a look for some good pix and clear, personable, often funny writing about a great range of up-to-the-minute plant issues.

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As you may know, this blog started as a series of posts on our other blog, Taking Place.  I branched it off that blog to avoid unbalancing the whole endeavor, and began posting on woody plant issues here.  I am currently working on copying older posts from Taking Place over to this blog as well (they’ll remain at Taking Place, too, as they are important there) — but it’s taking me a while.

So — if you want to read older posts on bare-root transplanting (root-washing and air-tool excavation), or on woody plants in design and woody plant management, you’ll be able to read current (from August onward) posts here, but will have to wait a bit for the older ones to arrive on this site.  If you just can’t wait, though, you can see all my pre-Taking Place In The Trees woody plants posts by clicking on the highlighted name — Taking Place — in the first paragraph.  That blog will then pop up.

Once that happens, scroll down and click on ‘Plants’ in the Categories list to the right of the page; doing so will make the list of tree and shrub posts pop up.  Scan through the list, and click on whatever title interests you to bring up the whole post, including some excellent photos.

And if you like what you see and read, take a look at the rest of the Taking Place site — there are some dandy photos and lots of observations on landscape architecture, design, and how we live in the green world.

Cute little dwarf liquidambar, freed from its container and soil washed away with the hose, ready to have its circling roots unwound, spread radially (as best as possible), and planted.

Cute little 'Gumball' dwarf Liquidambar, freed from its container and soil washed away with the hose, ready to have its circling roots unwound, spread radially (as best as possible), and planted.

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In the year since I’ve been writing about bare-root transplanting and air-tool use, I’ve had the great good fortune to be able to ask questions of the real experts, the arborists who are doing this work and promoting it throughout Massachusetts and the US.  Three in particular have been especially helpful:

Mike Furgal

Mike Furgal

Mike Furgal, the original developer of the air-tool bare-root transplant method, has patiently reviewed my articles and given thoughtful and well-considered answers to all my questions.  He has a tremendous amount of knowledge about trees and transplanting, and he is extremely generous in sharing it.

Matt Foti

Matt Foti

Matt Foti, who hosted the first MAA workshop on air-tool bare-root transplanting (given by Mike and Matt) at his nursery at Nonset Farm, has taken the time to discuss a wide range of tree-related issues with me, and to provide clarifications to help make this information as up-to-the-minute and accurate as possible.  He has been the catalyst to get word of bare-root work out to the MAA and beyond, and has put energy and dedication into practicing, experimenting, and teaching.  Another generous guy.

Carl Cathcart

Carl Cathcart

Carl Cathcart, Consulting Arborist, has provided encouragement and still more information to me from the day we met at the Nonset Farm workshop.  He alerted me to the Cavicchio’s root-washing experiment, he talks up my writing to other arborists, and his encouragement is what got me writing about this stuff in the first place.

In July, Matt and Mike transplanted a number of very large trees for a project in Wellesley, MA.  They (and the homeowner, contractor, and landscape architect) kindly allowed me and a colleague to videotape the moving of two forty-foot high London Plane trees.  Editing of over six hours of videotape is underway now, and I’m hopeful that I’ll have a decent film this fall that Matt and Mike can do some voiceover comments on (not possible on site — air-tools are incredibly loud!).    When we’re done, it should give a fairly comprehensive look at how this method works for transplanting significant trees.  (And I bet Carl’s going to talk it up…)

For all these reasons, I offer my sincerest thanks to Mike, Matt, and Carl.  They are models of generosity, and I couldn’t be more grateful.

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Air spade tree transplanting.  Warning:  Long post, tons of photos.

Probably the biggest draw of the Elm Bank workshop on September 10, 2009, was Mike Furgal’s moving of a 6″ caliper elm hybrid.  Mike first developed the method of air-tool bare-root transplanting in 2004, and has been working on it since, moving ornamental specimens and canopy trees with great success.  The biggest tree he has moved was a 21″ caliper, 50′ high mulberry (it was the owner’s choice), in November 2008; this past July he worked on Matt Foti’s project of moving several large trees, including the five 40′ high London plane trees showcased in posts on www.takingplace.net.

(To find those posts, click on the link in the last sentence, and then click on the ‘Plants’ link in Categories listed on the right side of the page.  All posts related to air-tool transplanting will pop up; the links for the London plane project are dated July 29, July 31, August 3, and August 7.  Browse among earlier ‘Plants’ posts for more articles on bare-root transplanting.)

So Mike has lots of experience with this work, and continues to think about the best ways — for the trees and for the crews — to move trees.  He made a number of observations in his Elm Bank talk about air-tool transplanting:

1.  The larger the tree, the more cost-effective the bare-root move is.

2.  Bare-root transplanting lets roots settle immediately into the soil on the new site.  With no root ball/surrounding soil interface to impede moisture saturation or interrupt moisture flow, the roots are able to adapt right away and start growing.  As a result, watering and aftercare are also easier and more effective.

3.  The greater the depth of good quality soil, the more apt roots are to grow down as well as out.

4.  Arborists and landscape architects MUST stress the need for sustained aftercare once a tree has been bare-root transplanted.  One year of attentive watering is good, but two, three, four, or even five years is better.

5.  Mike asked “Do we arborists plant trees or do we install them?”  When you install a B&B tree, he suggested, you dig a hole, put the tree in the ground, backfill, and water.  When you plant a tree, you remove the wire basket, remove the burlap and twine, possibly break up the soil mass, spread the roots out to promote outward growth, and water sufficiently for the next couple of years for the tree to root into its home.  ‘Installing’ a tree makes the tree simply a product, a commodity that can (and may have to be) replaced.  ‘Planting’ a tree recognizes and attends to the needs of this living organism, and promotes its good health and sustained long life.

6.  Air tools dry out root surfaces — pre-watering of the root mass and soil around a tree to be moved helps the tree hydrate and maintain turgor pressure during the transplant operation.  Mike suggested that trees may have a greater tolerance for short-term root drying than is commonly assumed, and urged the audience to observe what happens to the roots of trees they may move bare-root, and how those trees react to the process.

7.  When you use an air tool to excavate a tree for transplanting, dig your soil trench in sections, and dig it deep enough (measured in feet, not inches) to hold quite a bit of blown out soil, thus minimizing the number of times it needs to be emptied.  Mike pointed out that it’s necessary to consider how best to move the excess soil around; it’s important to plan the job at the outset, including how to access the plant(s) to be moved, how to avoid plants to remain, and where to stockpile the blown-out soil.

8.  The bare-root process can allow arborists use lighter equipment (depending on tree size, of course) than may be necessary for B&B trees.  A 2000-pound mini-excavator can pick up a six-inch elm, while to move that same tree B&B would require a large backhoe or front-end loader.

9.  The more fibrous a tree’s root system, the less likely it is to need cabling after a bare-root transplant.  A root mass’s size, the nature of its rooting, and the relationship between those factors and the tree’s size will also factor into the decision to cable a newly-planted bare-root tree.

Mike had blown soil out from around the roots of the Elm Bank elm the day before the workshop, and kept them covered until the workshop demonstrations began.

Healthy elm tree, soil blown off its roots, ready to be moved.

Healthy elm tree, soil blown off its roots, ready to be moved.

Closeup of the roots.  This root mass measured 14 feet across at its widest.  Roots have been pigtailed -- that is, tied together and lifted to keep them from breaking during the air-tool process and move.

Closeup of the roots. This root mass measured 14 feet across at its widest. Roots have been pigtailed -- that is, tied together and lifted to keep them from breaking during the air-tool excavation and move.

Dingo used to move the tree, whose new location was about fifty feet away from where it originally stood.

Dingo used to move the tree, whose new location was about fifty feet away from where it originally stood.

Mike Furgal and his assistant planning their course of action.  Note the tagline leading out from the canopy; it will be used to stabilize the tree during the move and backfill operation.

Mike Furgal and his assistant planning their course of action. Note the tagline leading out from the canopy; it will be used to stabilize the tree during the move and backfill operation.

Mike directs the Dingo forks under the root plate while his assistant holds the trunk stable.  Note the heavy burlap padding both on the Dingo and on the tree trunk.

Mike directs the Dingo forks under the root plate while his assistant holds the trunk stable. Note the heavy burlap padding both on the Dingo and on the tree trunk.

Lifting the tree.  Trunk padding rests on Dingo padding; tagline helps the trunk and canopy remain steady.

Lifting the tree. Trunk padding rests on Dingo padding; tagline helps the trunk and canopy remain steady.

Beginning to move the tree requires that it sit firmly on the forks, and remain balanced through the move.

Beginning to move the tree requires that it sit firmly on the forks, and remain balanced through the move.

Cutting the last few anchored roots, and any roots broken in the process.  Loppers work best; be sure they are sharp enough to make clean cuts (a set of root-pruning tools is useful, as cutting dirty roots with top-growth tools will ruin their blades quickly).

Cutting the last few anchored roots, and any roots broken in the process. Loppers work best; be sure they are sharp enough to make clean cuts (a set of root-pruning tools is useful, as cutting dirty roots with top-growth tools will ruin their blades quickly).

Moving the elm up its soil ramp and out of its plant bed; an attending arborist jumps in to help the roots past this thriving pine.

Moving the elm up its soil ramp and out of its plant bed; an attending arborist jumps in to help the roots past this thriving pine.

Elm tree on the move.  Stabilizing the trunk and moving slowly keeps the job safe.

Elm tree on the move. Stabilizing the trunk and moving slowly keeps the job safe.

Big canopy.  This year's growing season was moist and fairly cool, leading to lots of topgrowth and long twig extension.

Big canopy. This year's growing season was moist and fairly cool, leading to lots of topgrowth and long twig extension.

Mike steers the Dingo to the crater he has dug.  It is relatively shallow, to match the elm root mass depth, and wide (though not wide enough at first -- a couple of trenches had to be dug beyond the crater at the last minute to some extra-long roots).

Mike steers the Dingo to the crater he has dug. It is relatively shallow, to match the elm root mass depth, and wide (though not wide enough at first -- a couple of trenches had to be dug beyond the crater at the last minute to some extra-long roots).

Lowering the elm into its crater.

Lowering the elm into its crater.

Whoa!  A moment of excitement, when tree weight and crater's-edge sloped combined to tip the Dingo on its tracks.

Whoa! A moment of excitement, when tree weight and crater's-edge slope combined to tip the Dingo on its tracks.

The Iwo Jima shot.  A team of volunteers ran in to right the tree.

The Iwo Jima shot. A team of volunteers ran in to right the tree.

Holding the tree upright once the Dingo forks have been pulled out.

Holding the tree upright once the Dingo forks have been pulled out.

Again, holding the tree upright.  The pigtails now get cut open and roots spread out radially from the trunk.

Again, holding the tree upright. The pigtails now get cut open and roots spread out radially from the trunk.

Freeing the roots, beginning to dig in backfill, and watering to make a soil slurry that will eliminate air pockets and help anchor the spread-out root plate.

Freeing the roots, beginning to dig in backfill, and watering to make a soil slurry that will eliminate air pockets and help anchor the spread-out root plate.

With the tree in its new location, burlap padding the trunk may be removed.

With the tree in its new location, burlap padding the trunk may be removed.

Digging in the root mass.  It's important to pack the soil directly under the tree's trunk, to eliminate air holes and ensure against settling of the tree lower in its hole over time.

Digging in the root mass. It's important to pack the soil directly under the tree's trunk, to eliminate air holes and ensure against settling of the tree lower in its hole over time.

Big canopy on this tree, with a root mass to match.

Big canopy on this tree, with a root mass to match.

A bucket on the Dingo shakes backfill -- the native soil onsite in this case -- into the crater as workers wield shovels and a hose.

A bucket on the Dingo shakes backfill -- the native soil onsite in this case -- into the crater as workers wield shovels and a hose.

Trunk flare, placed in the proper relationship to finish grade.  Note the cut root ends; clean cuts with sharp tools let the wounds heal quickly.

Trunk flare, placed in the proper relationship to finish grade. Note the cut root ends; clean cuts with sharp tools let the wounds heal quickly.

More backfill, more water, and someone still holds the tagline for safety.  The Dingo never drives over the root mass, but drops soil onto it from outside.

More backfill, more water, and someone still holds the tagline for safety. The Dingo never drives over the root mass, but drops soil onto it from outside the planting hole.

Still more water, as the backfilling continues.

Still more water, as the backfilling continues.

Building the well wall, as water continues to flow.

Building the well wall, as water continues to flow.

Six-inch caliper elm tree in its new location.  Some wilt is evident -- likely because the tree was excavated the day before and the roots had been exposed through the course of the several-hours long workshop.

Six-inch caliper elm tree in its new location. Some wilt is evident -- likely because the tree was excavated the day before and the roots had been exposed through the course of the several-hours long workshop. The tagline finally lies slack. Two to four inches of mulch will next be added, and kept away from the trunk.

Demonstrating arborist at this station:

Mike Furgal, Furgal’s Tree and Landscape, Northborough, MA

Air spade tree transplanting

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Dave Leonard from Lexington, KY, manned the root forensics station at the September 10 MAA air-tool workshop at Elm Bank.  He used an Air Knife to excavate the root ball of a 4″ caliper red maple that was showing signs of decline.

Turf provided the only competition for this tree, but it was showing dieback and early fall color at the MAA workshop.

Turf provided the only competition for this tree, but it was showing dieback and early fall color at the MAA workshop. Dave Leonard excavated at its base to take a look at its rooting habit for possible problems.

With soil blown away from the original root ball, it was clear that the tree’s planting had initiated some problems — parts of the wire basket appeared at the edges of the root ball, and cut root ends had sent out an explosion of fibrous roots that turned back toward the trunk.

Root ends cut during the tree's digging in the nursery sent out masses of fibrous roots, quite a few of which turned back toward the trunk.  The interface between root ball soil and surrounding soil can inhibit root growth into the surrounding soil; removing burlap, removing the wire basket, and breaking up the root ball soil, particularly at the ball's perimeter, can help promote the spread of new roots.

Root ends cut during the tree's digging in the nursery sent out masses of fibrous roots, quite a few of which turned back toward the trunk. The interface between root ball soil and surrounding soil can inhibit root growth into the surrounding soil; removing burlap, removing the wire basket, and breaking up the root ball soil, particularly at the ball's perimeter, can help promote the spread of new roots. Note the soil line some inches up the trunk flare; removing soil above the trunk flare will also benefit the tree and lessen its stress.

Dave cut away the roots that he could not redirect outward, and trimmed off the roots that had begun to circle the trunk flare’s base, which would otherwise eventually girdle the trunk and major anchor roots.  Some of these roots were the beginnings of a secondary root system put out by the tree in response to its stress.

Removing the worst of the inward-growing and circling roots improves the tree's chances for survival.

Removing the worst of the inward-growing and circling roots improves the tree's chances for survival.

After excavating the root ball, Dave intended to continue to blow soil out away from the root ball, creating a shallow crater  out at least to the tree’s dripline.  Removing turf from that zone would eliminate plant competition for soil moisture; the addition of 2-4″ of mulch (kept away from the trunk) would help the soil retain moisture and an even temperature, add organics to it over time, and lessen the chance of soil compaction that inhibits soil/air gas exchange.

Dave said that he would also consider lifting the tree a few inches, to bring its trunk flare into a better relationship with surrounding grade.  This tree had been in the ground for a couple of years; Dave suggested that tree lifting might be worth doing within two to four years of planting, but could be detrimental to the tree after that.  (The window of opportunity for lifting a tree would be a lot wider if an air tool were used, rather than a Bobcat or excavator, as the tree could be bare-rooted and set back in place with relatively little stress from the process.)

Demonstrating arborist at this station:

Dave Leonard, Dave Leonard Consulting Arborist, Inc., Lexington, KY

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At the MAA Elm Bank workshop on September 10, 2009, Matt Foti demonstrated how to address root problems at the time of planting.  He had a fairly large collection of trunk-and-root masses to illustrate his points, and used them to show how girdling roots, secondary root systems, and J-rooted systems can develop as a result of poor planting or growing practices.

Matt first showed a couple of forest saplings he had pulled early in the day to illustrate how a naturally-seeded tree’s roots grow.  The sapling’s roots were evenly spaced around its stem, and extended out a distance relatively equivalent to the distance its topgrowth extended from the stem.

This little forest-grown white pine has a clean, evenly spaced root system.

This little forest-grown white pine has a clean, evenly spaced root system.

He then pointed to a couple of nursery-grown trees whose rooting problems had become evident after several years.

These root systems have been cut in the digging process.  In an attempt to regrow roots, the foreground tree has sent out a secondary root system, several of which are beginning to girdle other roots.  Kept too long in a burlapped ball or in a container, roots will often turn back in to the ball, making effective planting and long-term growth problematic.

These root systems have been cut in the digging process. In an attempt to regrow roots, the foreground tree has sent out a secondary root system, several of which are beginning to girdle other roots. Kept too long in a burlapped ball or in a container, roots will often turn back in to the ball, making effective planting and long-term growth problematic.

Shrubs as well as trees are susceptible to root problems; Matt dismantled an Ilex verticillata root mass to illustrate how he treats roots bound in a container or in burlap before planting.

Fibrous roots hold together in a near solid mass right out of the container.

Fibrous roots hold together in a near solid mass right out of the container.

Using a three-pronged fork to untangle the root mass.  For a bigger shrub or small tree, a machete or pitchfork may work well to loosen soil and reorient roots.

Using a three-pronged fork to untangle the root mass. For a bigger shrub or small tree, a machete or pitchfork may work well to loosen soil and reorient roots.

Ilex verticillata root mass, now ready for planting.

Ilex verticillata root mass, now ready for planting.

Soil can present another problem for nursery-dug B&B trees.  Clay soils make sturdy root balls, which can be useful for shipping, but not so great for root growth.

This pair of trees have root masses encased in rock-hard clay soils.  Note the solid clumps of clay in the foreground, and root growth only on top of the root ball -- these roots found it impossible to grow into and through this soil.  Breaking up the soil in a root ball like this before planting promotes the tree's future health; leaving this kind of root ball intact almost guarantees tree stress and decline.

This pair of trees have root masses encased in rock-hard clay soils. Note the solid clumps of clay in the foreground, and root growth only on top of the root ball -- these roots found it impossible to grow into and through this soil. Breaking up the soil in a root ball like this before planting promotes the tree's future health; leaving this kind of root ball intact almost guarantees tree stress and decline.

Closeup of rock-hard clay root ball, broken apart (fairly violently) for demonstration purposes.

Closeup of rock-hard clay root ball, broken apart (fairly violently) for demonstration purposes.

Another example of a dense clay root ball that constricted root growth to the tree's great detriment.  Soil had also been piled up around this tree's trunk flare, further challenging its ability to live.  Tough conditions for a tree to grow in.

Another example of a dense clay root ball that constricted root growth to the tree's great detriment. Soil had also been piled up around this tree's trunk flare, further challenging its ability to live. Tough conditions for a tree to grow in...

The point of these illustrations was to show how necessary it is, when planting a tree or shrub, to work with the root ball before covering it with soil.  Removing wire baskets, removing burlap, loosening or removing the soil, untangling roots as best as possible, pruning roots when necessary — all these tactics make up a strategy for promoting real tree growth.  Bare-root techniques have shown that a great deal of the work that arborists do these days is remedial — that is, is work intended to remedy poor growing, digging, or planting practices.  With the knowledge arborists now have of how root issues so obviously affect plant health, it only makes sense to attend to those issues early on, to avoid greater problems later.

Demonstrating arborist at this station:

Matt Foti, Matthew R. Foti Landscape and Tree Service, Inc., Lexington, MA

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Matt Foti took these photos from last week’s big transplant project, and they illustrate some useful points.

Air-tool excavation is a very messy process, and it bears mentioning again that eye, ear, head, and face protection are really necessary.  Mike Furgal is wearing a face mask here; a respirator would give him even greater lung protection.  Blowing a good sandy loam is one thing; when pebbles and small rocks show up in the soil they become missiles, so long sleeves and pants should also be worn.

Air-tool excavation is a very messy process, and it bears mentioning again that eye, ear, head, and face protection are really necessary. Mike Furgal is wearing a face mask here; a respirator would give him even greater lung protection. Blowing a good sandy loam is one thing; when pebbles and small rocks show up in the soil they become missiles, so long sleeves and pants should also be worn.

Here is what a well-tied tree looks like in transit.  Note how the roots have been carefully pigtailed, and tiebacks to the tree's trunk are done neatly and professionally, to preserve the roots during excavation and the move.

Here is what a well-tied tree looks like in transit. Note how the roots have been carefully pigtailed, and tiebacks to the tree's trunk are done neatly and professionally, to preserve the roots during excavation and the move.

This project took place in late July, during a week of 85-degree heat.  Leaf turgor pressure was maintained throughout by the trees themselves (aided with some in-process watering).

This project took place in late July, during a week of 85-degree heat. Leaf turgor pressure was maintained throughout by the trees themselves (aided with some in-process watering).

Keeping the pigtails neat from the start makes unbundling and spreading the roots fairly easy.  The tree is now resting in the crater dug for its new home; the crew will unbundle and spread the roots out radially, pack soil underneath them to help level the tree, and backfill, water, and mulch the transplant.  Using a forklift allows the arborists to look under the root plate and gauge its bottom profile, which helps in shaping the floor of the planting crater.

Keeping the pigtails neat from the start makes unbundling and spreading the roots fairly easy. The tree is now resting in the crater dug for its new home; the crew will unbundle and spread the roots out radially, pack soil underneath them to help level the tree, and backfill, water, and mulch the transplant. Using a forklift allows the arborists to look under the root plate and gauge its bottom profile, which helps in shaping the floor of the planting crater.

Project arborists:

Matthew R. Foti Landscape and Tree Service, Concord, MA

Furgal’s Tree and Landscape, Northborough, MA

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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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Tom Ryan*, my first landscape architecture mentor, and I have discussed the desirability of specifying that the trees and shrubs we design into a site be planted bare root whenever possible.   As long as the roots can be kept moist — something now entirely possible with the use of hydrogels — most nursery-grown plants fare better, are more apt to be planted in a way that promotes their future health, and are less expensive than B&B plants. And we all know that healthier plants mean more long-lived designs….

Nina Bassuk and the Urban Horticulture Institute at Cornell have put up on the web an outstanding illustrated tutorial on how to plant shrubs and trees bare root.

One of the challenges for landscape architects is to get more nurseries to offer bare-root plants for sale. Currently, balled-and-burlapped and container-grown are the most available kinds of woody plants in the nursery-to-contractor trade. Like any business, nurseries respond to demand.

Years ago, I was having a casual chat with the president of a local nursery and garden center, and asking why plant selections were limited to a number of fairly standard species and cultivars (I had recently assembled a plant list that specified some more unusual species than his large nursery carried). He told me that his nursery responded to demand; without greater demand for more variety, his business stuck with the standard choices. If more contractors were to bring him more complex lists, his nursery would be happy to accommodate them. It’s a bit of a chicken and egg argument — but essentially it means that continued and persistent demand will get results.

If landscape architects, through our planting choices and plant specifications, possess the ability to influence nursery offerings, then why shouldn’t we also be able to influence the method with which those offerings are packaged? With a greater understanding of the benefits of bare-root plants, perhaps more of us will start to specify bare-root plants, and so create the demand for nurseries to meet. It’s an idea worth exploring.

If you have had experience specifying bare-root plants for a project, we’d love it if you would write in and tell us about it.

Chionanthus retusus, Swan Point Cemetery

Chionanthus retusus, Swan Point Cemetery

*This September Tom will be named a Fellow of the American Society of Landscape Architects — a great honor for any landscape architect, and one that he fully deserves.

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