Q. I recently transplanted some huckleberry bushes. In the process it was necessary to cut the large taproot. Do I need to prune back the foliage? If so how much? Donald Bishop – University Place, WA
A. This can be explained using the concepts “supply & demand”. As any plant grows, both the shoots and the roots maintain equilibrium of supply & demand. The roots are supplying water, minerals and nutrients to the shoots and leaves (that in turn become suppliers of sugars generated from photosynthesis – to themselves, flowers fruits and the roots – but I digress). Roots at any given time have just enough capacity to supply the leaves the water and nutrients they need. It is not “cost effective” for the plant to maintain more capacity. If you remove some of the existing capacity the supply is diminished. A percentage of root system is always lost during transplanting. So the demand for water and nutrients from the would be greater than the supply. Different plants respond differently when this happens. Some wilt in an effort to reduce demand. Others slow down non-critical functions like flower or fruit production. One solution as you aluded to, is to prune back some of the foliage (shoots) to decrease the demand. When possible this is a good solution. You will have to estimate the percentage of root loss and remove the equivalent roots. Not an exact science by any means but plants will adjust as long as you are in the ballpark.