Tree Care Fact or Fiction

Marianne C. Ophardt
Washington State University Cooperative Extension
Area Extension Agent  

Fact or Fiction? Newly planted trees should be firmly staked to keep them from falling over in the wind. 

Fiction... for most trees planted by home gardeners.  Trees that were growing in containers or were dug with an adequate size root ball don’t need staking... unless they’re being planted on steep slopes or in windy areas.  However, bare root trees frequently require staking while the roots are becoming established. 

If a tree must be staked for stability, it should be done the right way.  When trees are staked correctly, the staking allows for a swaying movement of the trunk all the way down to the ground.  Improper staking leads to taller trees with thinner trunks, less taper to the trunk, and a smaller root system.  Bad staking can cause physical injury to the bark.  Trees that have been poorly staked with the staking supports left on too long are more likely to break over in the wind after the stakes are removed.

The correct way to stake a tree is to place the stakes as low as possible on the trunk and no higher than 2/3 the height of the tree.  Use flexible materials to tie the tree to the stake. Do not use wire! Insure that the trunk can move back and forth all the way to the ground.  Staking should never be left on any longer than needed.  It should be removed when the tree roots have grown and become established, never leaving it on more than one growing season.

Fact or Fiction?  When pruning large limbs off a tree, it’s important to cover the wound left on the tree with pruning paint or a wound dressing.

Fiction.  Pruning paint can actually deter a tree wound from healing.  It’s preferable for the wound made by the pruning cut to dry out, allowing the cambium at the edge of the wound to produce callus tissue and eventually close over the wound.  Pruning paint or wound dressing has been found to slow or inhibit the process.

Fact or Fiction?  Wounds made to the base of trees by mowers or weed eaters can lead to the death of the tree.

Fact. Damage caused to the base of trees by careless mower operators or weed trimmers is a serious problem that often leads to the death of a tree. The problem isn’t usually caused by a small, one time “oops” wound.  Major wounds that damage more than 50 per cent of the circumference of the tree seriously injure and weaken it, but it’s the repeated small wounds that can be the most deadly.  If these repeated injuries end up “girdling” or encircling the tree at the same point on the trunk, the tree will die. 

You often see problems with “mower blight” or “weed trimmer blight” in commercial landscapes and parks where grass is allowed to grow up to the trunk of a tree.  Repeated hits over time lead to the swollen tissues around the base of the tree where it flares outward.  This swollen tissue is wound tissue that has formed from repeated wounding.  The trees may also be thinning or dying back from the top down as a result of the injury and girdling.

To avoid problems from  “mower blight” or “weed trimmer blight”, mulch trees with bark or wood chips. The mulch helps control weeds, decreasing competition for water and nutrients, as well as decreasing the potential of mower or trimmer damage.  Research has shown that wood chip mulch can almost double plant growth the first few years after a tree is planted.  Use coarse textured organic mulches applied in a two to four-inch layer around the base of the tree, preferably the diameter of the planting hole or greater.

However, a layer of mulch greater than four inches deep or mulch placed directly next to the trunk can lead to problems.  Keep the mulch about four to six inches away from base of the trunk and don’t let the mulch become any deeper than four inches.

Fact or Fiction?  You can kill a tree by covering over troublesome tree roots that have “popped up” in the lawn with a layer of topsoil, even if the soil is only a few inches deep.

Fact.  Even a few inches of soil applied over tree roots can lead to serious problems and the gradual death of a tree.  This additional soil reduces the amount of oxygen reaching the roots and essentially suffocates the tree.  The amount of damage caused by filling in over tree roots varies with the type of tree, its age, and its health.  The scope of the damage also varies with the amount and type of fill.  Damage is not immediately evident.  It may only show up months or even several years after filling.

Fact or Fiction ?: The best time for planting a tree is in early spring before it leafs out. 

Fact... and fiction.  Horticulturists seem to disagree about the ideal time for planting trees.  Their recommendations vary from region to region.  The reason for this apparent disagreement seems to stem from regional differences in climate and available soil moisture. 

In some regions of the country, such as Western Washington, natural precipitation and subsequent soil moisture is most plentiful during the late fall and winter.  Because of more moderate conditions during the winter and plentiful soil moisture, root growth is possible ...making fall planting ideal on the west side of the mountains.  In the northeastern part of the country, soils during the winter are cold and root growth is minimal. Early spring planting, once the soil thaws, is best in these areas.

In our region it’s difficult for me to say with certainty whether spring or fall is the best time for planting, but I lean towards fall for planting.  However, trees and shrubs planted in the fall must be provided with adequate soil moisture, especially during mild fall and winter months.  A close second-best time to plant trees and shrubs is in the very early spring. The soil must also be kept moist to provide for root growth.  That’s the problem with fall planting and early spring planting in our region.  The best time for planting seems to be when many gardeners don’t have irrigation water available.  The solution is to water the trees with a hose.  Don’t wait until irrigation water is available.