Horticultural Myths
There have been several changes over the last 25 to 30 years involving some of the planting and
_____1. Dig a hole twice as wide and 1 and a half times as deep.
_____2. After planting B&B and especially bareroots plants, remove one third to one half of the top to
compensate for the root loss; to balance the top with the roots.
_____3. Always use pruning paints and wound dressings to seal and aid healing.
4. Make flush cuts when cutting branches from a tree trunk. Once the wound heals, no one will
know a limb had been there.
_____5. It is a good idea to mix some peat moss or other similar organic material into the back fill
when planting.
All are false. Do you know why these were changed?
1. Don’t dig a planting hole deeper than necessary when planting.
It was formerly suggested to dig a hole twice as wide and 1 and a half times as deep. The reason was
so that the new roots would have an easier time growing through loosen soil. It was noticed, however,
that the root systems would settle too much into the loosen soil; causing an unthrifty plant, slow
growth, root loss and death in severe cases.
2. Don’t perform compensatory pruning when planting; don’t remove one third to one half of a plant’s
top when planting; only remove broken branches.
It was assumed earlier to be logical to remove one third to one half of a plant’s top to help balance the
top with the roots, because bareroot and balled and burlapped plants loose a high percentage of their
roots during the harvest. It was later proven that a plant needs as much foliage as possible in order to
replace lost roots. Photosynthesis is required to produce roots and occurs in foliage.
3. Do not use pruning paints and wound dressings.
Pruning paints and wound dressings have since been proven to be ineffective or harmful. It was finally
realized that no earlier research had ever been performed. We were operating on assumption.
4. When cutting branches from the trunk, do not make flush cuts, leave the branch collar.
Research by
Alex Shigo and others discovered that the branch collar contained the cells required to close the wound
following branch removal. Flush cuts remove most of the branch collar and most of the regenerating
cells. The new recommendation is to leave the branch collar or shoulder to facilitate healing. This does
not mean a stub.
5. Soil amendments are generally not required when planting into individual holes within the
landscape.
Recent research found that soil amendments may encourage roots to stay within the amended area, and
not venture out into the native soil. The exception would be an extremely heavy clay soil that is poorly
drained or a droughty soil. To incorporate amendments into an entire bed is okay.
Mark Halcomb
University of Tennessee Agriculture Extension
Area Nursery Specialist
Comm/Consumer Hort./Holly Uses at Xmas Dec, 1999
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