Sealing cut after trimming large shrub
Should the cut branch of a large shrub be sealed after cutting? After trimming an old rose of Sharon (Diana) my gardener sealed the cut of the thick branches with a black substance. I was so surprised. Should the cuts be sealed? Is this ok?
No pruning paint or sealer is recommended as it can interfere with the healing process. Tree protect themselves from decay organisms through a process called compartmentalization and callus tissue is part of that defense mechanism.
Here is our publication on pruning and more information on large branch pruning. Do not cut the branch flush with the trunk, thus removing the collar. The collar is an area of natural shedding that contains chemically protective tissue that encourages rapid healing. http://extension.umd.edu/sites/extension.umd.edu/files/_docs/programs/hgic/HGIC_Pubs/TreesandShrubs/...