Root Washing – An Excellent Way To Plant Trees

Containerized plants and planting problems;

Containerized trees allow planting just about any time of the year in these parts.  But one of the most frequent, and disappointing, discoveries for us is finding them planted incorrectly.  Trees fail quickly when planted too deep, or from the circling or girdling roots commonly found in containerized plants.  That’s any plant grown in a container regardless of size including grow bags.

Balled and burlapped plants;

Balled and burlapped, (b&b) and grow bag plants nearly always come with excess soil piled around the trunk (stem) and are sometimes tagged to plant it at the nursery depth.  Trouble is most people don’t know what the nursery depth is.  Without completely removing the burlap and ties and excess soil around the stem and inspecting the roots, there can be no way of knowing if there is a problem or how deep to plant.   The same problem exists for potted plants, especially older, larger caliper trees.  So the soil should be removed from the roots before planting and the best way is to wash it off completely.

Root washing;

Root washing allows identification of the first primary roots so the correct planting depth can be determined.  It also eliminates the soil interface problem.  Planting in different soil than the plants were grown in creates the interface problem.  Plants must grow roots into the surrounding planting soil to survive but often they “choose” not to and they usually die.  Poorly rooted plants should be rejected and returned.  There is no reason to wait to plant containerized plants as they can be washed in full leaf, even in bloom, as this Royal Raindrop Crabapple was.  This tree came in a grow bag.

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April in full bloom

Soaking the roots overnight or longer in water loosens the nursery soil and allows for easy soil removal with a gentle spray from a garden hose.  A wheel barrow or plastic drum works well for this step so you can dump excess water.

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Root Pruning;

With the soil gone, inspection and root pruning is next.  Any root that is totally brown when scratched with a fingernail is dead and should be pruned off.   If there is any mold or decay on the stem or roots the plants should be rejected. Any dead or “J” roots (shown below on the left) at the bottom or sides of the root mass should be pruned back with sharp tools.  Any adventitious roots (small roots on the stem above the first primary root in the picture below on the right) growing above the first primary roots, should be pruned off .  The primary roots create a flare, that’s the ideal depth to plant, so the flare is visible.

diagram2Planting;

Planting hole size and shape is very important.  A shallow, wide dish shaped hole is the shape needed.  The hole should be no deeper than the bottom of the root mass (the root plate) and at least three times the width of the root mass.  The root plate should set on firm soil so the first primary roots are slightly above the finished grade.   If needed, create a small mound under the stem for support as shown.  This root system resembled a upturned water glass when washed, hence the mound.

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Notice the root pruning that was done before planting, all of the circling roots and adventitious roots are gone.  The correct planting depth would be at the root flare with the first root attachments visible.

Backfilling and temporary anchoring;

Backfilling with a soil*/water slurry and gloved hands places soil in and around all the roots, this is a vital step.  It may take more than one session with the hose and soil so if need be, let the water drain down and go at it again to make sure there is root to soil contact.  Constant moisture is critical to survival with this technique, so the soil should not dry out more than an 1” deep on the surface before watering again.

If the tree moves too easily when planting, there may be a need for temporary, loose anchoring but not usually with this method.  The soil to root contact makes a secure enough anchor for the tree to develop normally unless the root system is minimal or severe pruning was needed.  Rigid anchoring from several points will limit the trees ability to grow a supportive root system, so loose is the word if needed at all.  Anchoring was not needed for this tree.

* It’s best to plant in soil you expect the tree to grow in for the rest of its life. We don’t recommend amendments in most cases.  If your soil appears unfit, we’d be glad to visit and analyze the soil before you plant. Consulting fees would apply.

Results;

This is the same tree one year later Untitled-7

and today 4/30/13.

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As you can see, it is a real knockout now. Remember, it was root washed and planted in full bloom, and watered frequently during the first summer.  It was treated with our SuperRoots Bio-Fertilizer at planting and on an annual basis.

Jim Flott and Dr. Linda Chalker-Scott root washing a grow bag tree at an ISA workshop.

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Grower/Certified Aroborist Jim Barborinas at an International Assoc. of Arboriculture field day explains the grow bag container system.

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The roots grow through the bag into the soil and are removed when the bag is removed leaving a knob where new roots grow from. Jim recommends removing the grow bag completely before planting.

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A grow bag tree prepared to ship.

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This grow bag tree was chosen to root wash. All the soil is removed with a garden hose first, then the adventitious roots on the stem above the primary roots and a “J” root were pruned off, shown below.rw9

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Jim Flott begins root washing.

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Jim showing where the first primary root is located.

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Ready to plant.

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Dr. Linda Chalker-Scott, WSU Research, holds the tree while Jim adds water and uses his gloved hands to distribute the soil slurry into the root ball. Notice the tape on the stem showing where the soil line was in the grow bag before root washing and the dish shape of the planting hole.

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Mixing soil and water until all the roots are covered and the voids are all filled. Notice the first primary root visible above the finished grade and how much soil was removed from the stem in washing. Had the tree been planted without root washing, that soil may not have been removed and the tree would have planted too deep.

Unwashed B & B and grow bag trees are heavy and will subside in loosely compacted soils, further complicating the planting depth problem. Washed trees weigh very little and are not typically subject to subsidence problems.

It is imperative that the soil doesn’t dry out for the first growing season for any transplanted tree, particularly those that have been root washed.

Poor Planting Failures

This planting of over 70 Giant Sequoias started to fail within a few years of planting.

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Air spading by Consulting Arborist Rob Lloyd revealed the grow bag still intact and the girdling roots strangling this tree. The damage is too far advanced to repair by root pruning so all the trees were removed.

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The effects of the girdling roots caused by improper planting are telling. All the trees were planted with the bags just turned down about 1/3 but left intact on the other 2/3 of the root ball.

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The classic “bottle butt”, evidence of girdling roots.

Removing the grow bags and redirecting the roots at planting may have saved these trees, but there were deeper problems that would have gone unnoticed had they not been root washed.  Root washing these trees and planting correctly would have cost much less than estimated cost of removal and replacement of $50,000-$60,000 +, to say nothing of the heartache the owner felt watching them decline and fail.