What About Mulching?

Monday, October 17, 2011

We use mulch to keep down weeds, retain soil moisture, and provide a pleasing background in the spaces between plants. An organic mulch will also add needed organic matter to the soil as it breaks down over time.

The best mulches are shredded or chopped bark. The bark is a by-product of lumber production; cutting down an entire tree to grind it up into mulch doesn’t make environmental sense.

A mulch of stones or pebbles can be very attractive and is useful right next to a building, where an organic mulch would give termites a place to nest against the wall. When thinking about stone mulches, however, remember that leaves and weeds will have to be removed faithfully to keep a groomed appearance. Shredded rubber mulches are made from recycled tires, but they do not add organic matter to the soil, and there are reports that if a fire ever gets started in a rubber mulch it can be very difficult to put out. Use with caution.



Photo caption: bad mulching

In choosing mulch materials, keep in mind that you want people to admire your design and your plants, not your mulch. A natural-colored mulch will disappear into the background, while one of those brightly dyed mulches will compete for attention.

In mulching it’s not a case of “more is better”. Any more than an inch or two encourages plants to root into the surface mulch rather than reaching down into the ground for water. The mulch “volcanoes” you see around young trees are a crying shame. The pile of mulch keeps moisture against the trunk of the tree, helping fungi invade and promoting rot. Mice and voles will make a home there in the winter and dine on the bark. The tree’s roots will grow upward into the mulch, and in a few years the damage to the tree will be painfully evident – and impossible to fix. Instead, when you put down the couple of inches of mulch, pull it several inches away from the stems of all trees and shrubs.


Photo caption: an example of bad mulching


By guest blogger, Jessica Milstead. Jessica has been a Charles County Master Gardener since 2002 and is certified to elevate gardens and landscapes for their adherence to Bay-Wise principles.

Photos (courtesy of Master Gardener Marge LaMar) show a crape myrtle with a light blanket of mulch over the whole area (good!) and a poor lonely tree with mulch piled high around the trunk (very sad!) The cartoon is fun, but it has those volcanoes that should be forbidden.