How and when to trim your trees

When is the right time to trim your trees?

There's an old saying about trimming trees:
"It's OK to trim anytime the saw is sharp"

When it comes to taking out dead or broken branches that saying may be true, however, when it comes to flowering trees:

"Timing is everything"

Flowering Dogwood
Trimming this dogwood in late summer or fall would
have removed most of these spring blossoms!

Flowers formed on "old wood"
Flowering trees won't bloom if they are trimmed after flower buds are "set."  The safest rule of thumb is to only trim flowering trees during the 30-day period right after they bloom.

Don't risk pruning off the flower show
you've waited an entire year to see!


Other kinds of "timing" for tree trimming
There are other trees that shouldn't be pruned certain times of the year, due to disease and insect prevalence: 

  • OAKS (Quercus sp.) - It's generally recommended that Oaks not be trimmed from April through October since this will make them more susceptible to Oak Wilt disease. 

  • DOGWOODS (Cornus sp.) - Dogwoods trimmed in April or May are more likely to attract the dogwood borer; an insect that bores into the trunk and severely damages the vascular system.

  • MAPLES (Acer sp.) - Maples are known as "bleeders".  This means they will drip from pruning wounds if they are cut in seasons when the leaves are off, but they aren't fully dormant.   Recent university research has shown that "bleeding" doesn't really hurt the tree.  However, if you want to prune without bleeding, a Maple must be pruned when it is fully dormant; Mid-Winter -or- Spring/Summer when it is fully leafed out.

Trimming a Japanese Maple



This sort of tree "topping" has many detrimental results.... permanent structural damage to the tree, profuse sprout production, and possible tree death. Note the weak, fast growing, upright sprouts on the Maple shown below that was 'topped' years earlier.

New growth on a Silver Maple that was previously topped

The right Place to trim trees

The biggest pruning mistake we see are branches cut in the wrong place.  Most amateurs tend to leave too much of a "stub" when they remove a branch.  The problem is, once this stub dies off, it creates a perfect entry point for insects and disease pathogens.
Trees don't regenerate tissue the same way human beings do.  While our skin acts to replace itself, trees grow new tissue around their wounds in a process known as "compartmentalization".   If a tree can compartmentalize an old pruning wound, it has a much better chance of survival.  Also, efforts should be made not to create wounds on tree trunks with lawn mowers and other machinery.  Destructive fungi are opportunists!
Trees have a natural defense system built into the swollen area known as the "collar" where the branch meets the trunk.  It is important to make a "flush cut" close to the trunk, without removing the collar.  The proper cut is made just beyond the collar, not leaving a stub, but leaving the swollen area intact.

tree branch collar
DON'T leave a stub, but DO leave the 'collar' at the base of a branch, since a tree has natural defenses there. Always make 'clean cuts.'

The first step in removing a branch is getting the weight off:

  • Go out a foot or two from the trunk and first make an undercut 1/3 of the way up from the bottom of the branch.   If you go too far, your saw will get pinched.

  • Then make your second cut all the way through the branch from the top side of the branch, just an inch or two outward from your first cut.

  • The branch should then fall away without tearing bark back to the trunk.  Maples always want to tear.

  • Safety - Never attempt tree work that should be done by a professional.  Trees can wound or kill in the blink of an eye!

  • A few safety TIPS:

    • Never cut or trim trees from a ladder. This is asking for trouble!

    • Tie-in to a tree at least two places:
      1) With an approved safety line through a strong crotch higher up in the tree -and-
      2) With the strap on your professional tree saddle

    • Follow recommendations for properly "notching" a tree trunk when you are cutting down a tree.  Kickback will kill!  A friend's father was killed when a locust tree kicked back in his face.  And he was an experienced woodsman.

    • Take an approved course in chain saw practices and safety, and apply what you learn.  Chain saws cut like "a knife through butter" when they contact skin!  Loggers wear special pants lined with Kevlar and other materials to protect their legs from chain saws.

    • Wear a hardhat and eye protection (also wear ear protection with chain saws).   Consider other safety equipment and advice as well.

Pine "Candles"
Shearing the new growth on pines in June
keeps the tree shapely and dense

white pines

Trimming makes a BIG difference
in the size of a tree years later!
Above: White Pines sheared every year
Below: White Pine without any trimming.
White pines grow 3 feet per year!

Naturally growing White Pine


Construction Damage to Trees

Deer resistant flower bulbs

Fertilizer burn on lawns


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