From Garden Talk with Doug – Mulching by Doug Hensel
Now that spring has arrived there is a lot of mulching going on by homeowners and by landscape firms. Unfortunately, I observe too many improper mulching habits.
Mulching, whether with pine bark, hardwood, or pine needles can be a great value to shrubs and trees when done correctly. Some benefits of proper mulching are:
There are some problems associated by over mulching your beds. Repeated or deep application of mulch does not allow shrub or tree roots to get enough oxygen and breath. Without oxygen, root growth declines which can lead to plant failure. If your mulch is piled in a “volcano” shape high up on the trunk, it decreases and kills the inner bark and roots can no longer receive food from the leaves. Remember to keep the bark dry and roots moist, and deep layers of mulch against the trunk provides a perfect habitat for pests.
The proper amount of mulch at any one time is 2 – 4 inches. If a fresh look is desired each season, take some of the old mulch away before adding a new layer to reach the 2 – 4″ depth.
Remember, mulch out, not up!