Should I Mulch Around Trees?
If you have a naturalized landscape with established trees, there is no reason to mulch around them. Fall leaf or needle drop is natural mulch. If you have a more manicured landscape, it is a good idea to mulch around trees, but care must be taken to keep the mulch away from the trunk of the trees. So called “mulch volcanoes,” wherein mulch is piled around the trunk of the tree, can have long term detrimental effects as it can become waterlogged, compact, harbor rodents and introduce pathogens.
When to Mulch
Mulch is used for aesthetic purposes, to retain moisture and nutrients, slow weeds, and to protect root systems. If you are mulching to protect plants from winter freezes, apply mulch in the fall. Otherwise, mulch should be applied in the spring. Of course timing is everything. Wait as long as possible to mulch in the spring. Allow the ground to warm and dry out somewhat before applying mulch. Mulch applied too early in the season inhibits soil warming and can also foster disease while compacting soil, lessening aeration. There is no reason to remove mulch in the spring, provided it is organic. Organic mulch breaks down and is then incorporated into the soil adding valuable nutrients. You should however loosen up the old mulch to allow for air flow and water penetration. If you have completely covered a plant with mulch as winter protection, do remove mulch covering the plant. When exactly to apply mulch depends on your location. Your local extension office can assist you with spring mulching tips for your area although mid to late spring is generally idea. Delay applying mulch until May or June if the weather has been particularly cool and wet.
How to Mulch
How to mulch depends upon the type of mulch used and the plant. If you are using bark to enhance the landscape, a scant inch or two (2.5-5 cm.) is sufficient. Otherwise a depth of 2-2.5 inches (5-6.3 cm.) of mulch is sufficient for weed control, moisture retention and root protection. Applying more than this amount can lead to water logged soil, compaction, diseases and rodent infestation. Especially at risk are plants with shallow root systems such as azaleas, rhododendrons, most conifers and especially yews and taxus varieties.
