Root Washing

 Root washing- should you do it?

By Kim Willis These articles are copyrighted and may not be copied or used without the permission of the author.

Many garden professionals are now advocating that all the soil be washed off the roots of trees and shrubs that you purchase in pots or that are balled and burlapped.  When you remove the soil, you can see the root system and correct any problems or if the plant ‘s roots are in horrible shape, you can return it for a refund- sometimes.  Some experts think removing the soil around the roots helps plants adjust more quickly to the new soil they will be planted into.

To root wash all you do is remove pots or burlap and use a hose to gently wash away all the soil. If you can’t use a hose, you can sometimes use buckets of water or set the plants roots in a tub off water and swish it gently.  It can take a little work to get all the soil out if the plant is badly pot bound.

 After the soil is washed away you can untangle the roots, clip off badly circling roots, and spread the roots out. (See the section below about helping roots grow right.)  Keep the roots damp as you work on them. Washing the roots doesn’t usually damage them much, so don’t worry about that.  And roots can withstand a bit of pruning without harm too. 

If you root wash, you must be prepared to plant the tree or shrub immediately after the soil is washed away and problems corrected.  You can’t leave it sitting in the open air where the roots will dry out.  If you are planting several trees at once you could wrap the washed roots in wet cloth or paper for an hour or so.  Keep them out of the wind and sun until planted.

I am not totally swayed by the root washing theory, at least for all plants.  If I remove the pot or burlap and there are few roots on the outside of the root ball, I remove a bit of potting soil at the top until I uncover the top horizontal root to find the correct planting depth and leave it at that. Sometimes a gentle shake or thump will dislodge enough soil so the roots can be seen. If soil crumbles away from the roots and I can spread them easily horizontally I will plant those trees without washing the roots.

If you remove a tree or shrub from a pot or burlap and you see that the rootball is very root bound and there appears to be circling roots, then it’s a good idea to wash off the soil and examine the root structure.  For very expensive trees or shrubs a careful root washing might be a good precaution.

If you wash the roots and the plant has badly circling roots, the worse case scenario, you may want to take it back to where you purchased it for a refund/replacement.  The plant will probably not survive if planted like this. However, some places may not accept a plant back that’s been root washed and is out of the container.  That’s wrong, but it’s a hard thing to challenge. 

 

Helping roots grow right

 

When planting trees never wrap a root around the hole- spread it out horizontally.  If it’s really too long, trim it off to fit the hole, but never spiral it around the hole.  When you see those roots that have circled the pot as described above, they must be loosened before replacing soil.   If you can loosen them with your fingers and spread them out that’s a sign the circling wasn’t too advanced.   Good nurseries either root trim or repot trees to keep them from getting root bound.

If the roots are thickly layered at the bottom of the pot or root ball or around the sides you’ll need to trim them.  If it’s just at the bottom, trim off the circling roots, making a slice across the bottom an inch or so deep.  Then slightly flare out the remaining soil and roots.  If roots are really circled heavily up the side of the pot make several cuts length wise through the roots, as well as trimming the bottom, and hope for the best.

Roots that are circling when planted will probably continue to spiral around the main root or trunk.  This may eventually kill the tree by choking off the supply of water and food, sometimes years after planting. 

Spread roots sideways in the planting hole, except for any central main root.   Don’t squish all the roots down vertically into the hole.   Any larger roots that are broken can be trimmed.

Refill with what you removed

You’ll see the signs advising you to buy amendments and the sales staff may try to convince you, but don’t buy peat or topsoil or anything else to add to the planting soil as you plant your tree.  Research has shown that trees establish better if the hole is refilled with what you took out.  After all, that is the soil that the tree will be living in after the roots grow through your small amended area.  It is easier for the tree to adapt to new conditions if it starts right away and it doesn’t have to re-adjust its root system when it grows through the amendments and into the surrounding soil.

 Holes filled with “good stuff” may hold too much moisture next to roots, especially if you throw a bag of peat into heavy clay soil.  The roots sit in water and rot.  And trees may not extend their roots quickly into surrounding soil if it’s easier to grow roots inside an amended area.  This can lead to circling roots, with the tree being strangled or to a poorly established root system that can’t support the tree in a wind storm or through a drought.

You can add a little slow release fertilizer to the soil you are going to backfill with.  Don’t throw it in the hole, mix it into the soil you removed and then refill the hole.