Trees should not be "Thinned"
It will not help the grass grow beneath the tree canopy
Grass does not grow well in the shade of large trees; that is a fact. The canopies of healthy mature trees provide important shade, but interior foliage should never be removed to increase light penetration to the soil below. The growth of your grass is being hindered by a lack of moisture and the tree roots. Mulch is recommended under tree canopies because it looks nice, eliminates the need to mow, reduces water loss, and adds organic nutrients that benefit the tree.
Thinning the Canopy Causes Tree Decline
- When the inside of a tree is stripped of foliage, the weight increases on the ends of those branches. This type of pruning is referred to as lion-tailing and creates a whip effect that makes limbs more likely to snap in strong winds.
- Interior bark may be sunburned when the harsh summer rays blast it after the foliage has been removed.
- Removing too much live foliage will reduce the tree's photosynthetic potential and reduce its ability to feed itself.
- Thinning the tree may cause it to panic and rapidly produce epicormic sprouting. Rapid growth depletes carbohydrate reserves, leaving the tree unable to defend against insects and disease.
So What Is Proper Pruning?
Certified arborists follow science-based guidelines that focus on the long-term health of the tree. Not all trees require routine or repeated pruning. The growth habit of a tree is written in its genetics, but influenced by its environment and available space. Pruning work should have a clearly defined goal that improves tree structure or health. In some circumstances, pruning must occur to eliminate clashes with surrounding structures or to reduce risk. Although common, pruning a tree to shape it and make its appearance more aesthetically pleasing can be detrimental.
Pruning should include:
Removal of dead, damaged, broken, or diseased branches
Proper cuts which promote compartmentalization (healing)
Preservation of the natural form and growth habit
Retention of the inner branches and foliage
Proper pruning leaves a tree looking untouched and natural. Pruning should always have a purpose.
Never allow someone to thin, clear out the inside, or lion-tail your healthy tree. All these terms are red flags. Modern arboriculture has moved far beyond those outdated practices.