Tips for Beginners
Old Field, New York
Reprinted from the New York Chapter newsletter, Oct.-Nov. 2005
While gardeners differ in opinion on the finer points of rhododendron culture, it is universally accepted that root bound container grown plants benefit dramatically if their root systems are disturbed before planting. We differ in opinion on the finer points, and I am aware of several methods to accomplish this end. Perhaps the most dramatic is that used by a member of the Tappan Zee Chapter who removes the plant from the container, lifts it as high as she can over her head and drops it onto a hard surface. I would like to share another method that is essentially based on the natural root growth pattern of rhododendrons and azaleas. As anyone who has moved a field grown plant of this type knows, the root system is wide and shallow. The width usually extends to the outer edge of the plant’s drip line and the depths usually 3 to 5 inches. Container grown plants develop root systems that essentially fill the container in which they’re grown, invariably deeper than wide. This pot configuration derives from economic factors and other considerations associated with commercial growing.
Before planting a container grown root bound specimen, I remove the bottom third of the root ball by making a horizontal cut with a hand-pruning saw. This first step eliminates deep roots that will not support plant growth in the ground and creates a general proportion consistent with natural root growth habit—wide and shallow, admittedly, not as wide as one might like. With the same pruning saw, I make diagonal cuts around the diameter of what remains of the root ball. If there is a well-defined root mass at what I call the shoulder of the root ball, upper/outer edge, I remove it with a box cutter.
Having prepared a plant in this manner can sometimes diminish root mass to a point that the plant should be supported with a thin garden stake tied to a sturdy upper branch for stability. This is more important in plants that are taller in form than low mounding varieties. I have always experienced sufficient root growth the first full year after planting to remove the stake. More importantly, this planting method accelerates normal root growth and acclimation to garden growing conditions. By the way, use an old pruning saw if you employ this method, as cutting through potting medium will ruin the blade and render the tool useless except as noted above.