Springtime! The most dangerous time of year for tree health. Not snow and ice, not wind, not even precipitation extremes cause as much damage to young trees as lawnmowers. The amount of stress will depending on the species, subsequent weather conditions and extent of the wound but it is unlikely it will ever have the same vigor that it had before the mower-attack. The tree may even become hazardous later in life as a result of our carelessness.
Readjusting to the capabilities of our mowers and of our skills in getting as close as possible without nicking the bark is an annual effort for those who care about their investment in their trees.
The good news is that it is not necessary. Appropriate mulching around our trees makes it unnecessary to mow or trim close to the trunks and now is the second best time to mulch (last week was the best time).
One method is to remove all the grass around the tree trunk to a radius of about two feet. More is better - some professionals recommend extending mulch to the drip-line of the tree but this may be unrealistic for older trees even though it would cut down mowing-time!
An alternate method that is easier and possibly more effective than removing the grass is to determine the area you want the mulch to occupy and then use corrugated cardboard or 3-5 sheets of newspaper to cover the grass in that area. Make sure there are no gaps which would allow grass to grow. Once the cardboard/newspaper cover is in place, put down an organic mulch (rather than stone which can become overly warm) such as cocoa hulls, hardwood or pine bark. Might want to consider that rather than being a by-product as it used to be, cypress mulch is now more often derived from trees harvested for that purpose. There is no reason other than taste to use dyed mulch and the dyes can be messy to work with.
The mulch should be placed 2-3" thick over the cover. If put on any thicker the roots may not get the oxygen they need which will encourage new roots to grow above the original ones which leads to the perched tree look and also to girdling roots neither of which is good for the tree.
Mulch should not touch the trunk - rather than coming up around the trunk uniformly, leave a space (a 'doughnut') of about two inches all the way around. This is too often ignored by planters who apparently believe it looks tidier. Mulch against the trunk can lead to fungal or insect problems.
There! a neat looking circle of mulch which will make it unnecessary for mowers to get close to the trunk because grass will not grow through the underlayment of cardboard or newspaper and mulch layer. A side benefit is that moisture will not evaporate from the soil which might allow the root ball of younger trees to dry out and could increase the chance of survival during a drought period.
Trees in Camp Tupper were mulched using this method when Barbra Garverick, Rhea Bockhorst and Ken Morrison who are all Marietta Tree Commissioners worked with Marietta College students on Community Service Day in March.
As for any wound caused by a mower, research has shown it will heal better in the presence of oxygen than under any wound dressing we might slather on in a fit of guilt.
If you want to have mulch with additional benefits that is all natural and home grown, collect the seed balls from under a sweetgum tree. This mulch over the same underlayment will deter slugs and cats from visiting the mulch. And the price is right! I don't know of anyone who would object to their sweetgum balls being removed.
Marilyn Ortt of 701 Colegate Drive, Marietta, is a member of the Marietta City Tree Commission. Our Earth appears on alternate weeks in the weekend edition.
