Much to learn about mulching
Updated 11:22 am, Friday, May 3, 2013
Spring has sprung in all her glory, and with that comes our gardener's need to mulch something. But before you jump on that mulch wagon, there's a thing or two you should know about mulching.
Mulching is not a new concept; Mother Nature has been perfecting it since the very first leaf and pine needle fell to the ground. If in doubt, just look at the ground in the woods; the layers of leaves and needles that have fallen over the years have matted together to create a very effective natural mulch.
We can learn a huge lesson from nature here: For starters there are very few weeds poking up between the trees, and if you were to scuff down, even during a dry period you'd notice the soil beneath is both cool and moist. That, my friends, is exactly what an effective mulch is supposed to do: Limit weed growth, keep the soil temperature modified and help the soil retain moisture.
Ah, but there's more nature tossed in for good measure; As the leaves and needles decay, they add to the organic matter of the soil, and this organic matter is used by the plants for nutrients year after year and by the soil to improve its moisture-holding capacity.
Another benefit is erosion control. On hillsides, that mat of last year's leaves is protecting the soil surface from the impact of raindrops and allowing water to slowly filter downward, which reduces runoff and improves water absorption, benefiting both the plants and the soil.
Studies have shown that mulching our beds can reduce summer soil temperatures up to 13 degrees, reduce the time it takes to weed by at least two-thirds and retain double the soil moisture retention of an un-mulched area. In plant language, cooler soil temperatures allow for better root function and higher soil moisture keeps plants hydrated while reducing the need to water. The reduced weeding time goes without saying in our busy lives.
There are bagged and bulk, chipped and shredded bark mulches; many types of bark mulch come in colors, such as red or jet black. Most, if not all, are now dyed using natural products or vegetable dyes, which have no adverse effects on your plant's health. However, if in doubt, ask before you buy; the seller should know.
If using wood chip mulch, its origin is important. You do not want one that includes shredded or chipped pressure-treated wood products. Wood chips available through municipalities and utility companies are typically hard and soft wood trees simply chipped up, old Christmas trees, pruned trees from under power lines. Again, asking never hurt anyone.
Before applying mulch, clear the soil of all weeds, or they will simply grow up through. If mulching a landscape bed, consider laying a fabric weed mat over the top of the soil, then applying the mulch on top, to help deter seeds from germinating between the mulch and soil layer. Perennial beds and areas where ground covers are grown should only be mulched; do not apply fabric, as it will interfere with their spread.
Rule of thumb: Mulch should never be applied thicker than 3 inches. Always taper it inward toward the stems, canes or trunk. Never mound it up around the shrub's stems or tree's trunk so it looks like a volcano. The plant "breathes" through its trunk, canes and stems. When mulch is mounded up around it, the plant suffocates. If in doubt, look at the top of a tree mulched in this manner come summer, and see how much thinner its canopy is.
To freshen existing mulch, simply rake it and re-grade. In doing so, you will also expose any weed seeds that landed on top and are trying to germinate. If you want to freshen the mulch by applying new and already have the recommended 3-inch depth, work the old mulch into the soil, so it can decompose. Rake the surface smooth and then mulch.