By Lois Scott, Master Gardener

Let’s talk root flares on trees.  The root flare is the part of the tree where the trunk turns into the roots and the root flare needs to be at the soil surface. 

People are often counseled that plants should be planted in the ground at the same level they were planted in the pot.  In my tree and shrub planting experience I have usually found the root flare submerged in the potting medium.  If I planted at this same level, it would mean their roots would be buried too deeply.  Roots need oxygen and when they don’t get enough, they are not efficient at taking up water or nutrients which thereby starves the rest of the plant.  Some trees can struggle along for a number of years but extra soil on top of fine roots can mean an early death sentence for your tree.  It gives some truth to the adage “plant it high it won’t die, plant it low, it won’t grow”.

When I bring home a woody plant, I like to get the potting medium off the roots by root washing the root ball.  Root washing is a process very well described by Dr. Linda Chalker-Scott.  https://gardenprofessors.com/why-root-washing-is-important-an-illustrated-cautionary-tale/  It is helpful to have a dormant plant (although I don’t always practice what I preach) and to do this on a cool day in the shade.  I put the root ball in my wheelbarrow and use the hose to rinse/blast the potting medium off.   Sometimes this can take quite a while!  Then I look at the root ball to establish where the root flare is and to also check for and remove problematic circling and adventitious roots (roots that grow from non-root plant tissues such as stems).  When planting I backfill with the soil removed from the planting hole and mulch with a wood chip mulch.  It is best not to mulch with sheet mulching like cardboard or paper and never, never, never with landscape fabric.

Providing the best planting situation for your new tree or shrub will hopefully promote the best growth possible.

Resource

Chalker-Scott, L.  How Plants Work (2015).  Timber Press Inc, Portland, Oregon.

All photos by Lois Scott