Mulching A Vermont Landscape
Spring is upon us here in the Champlain Valley and even with the snow on Tuesday the grass is greening and trees are beginning to break bud. Spring brings the landscapers out of hibernation and crews are out all over town cleaning-up from a long winter and helping the landscape wake-up into the warmer weather. The number one thing in Chittenden County we see landscapers doing right now is mulching. Mulching is an exceptionally helpful enhancement you can make to your landscape in performed correctly—sadly many mulch jobs are “dump and run” and cause more detriment to the landscape than good. Why do we mulch? If you asked most homeowners they would tell you we mulch for aesthetic reasons—which is a reason, but it is not the primary reason. Mulch reduces soil erosion from rain drop action. The layer of mulch absorbs the impact of falling rain drops and helps keep drops from displacing soil into runoff. Mulch regulates soil temperature—keeping the soil cooler in the heat of summer, and protecting plants in the deep freeze of winter. Mulch also helps regulate soil moisture and reduces evaporation—the layer of mulch keeps the water in the soil from evaporating. Mulch can, under traffic situations (walking paths) help reduce soil compaction as it provides a cushion. As mulch breaks down it adds organic material to the soil which in turn aids in improving soil capacity for nutrients as well as water management. In nature plants self-mulch using a duff layer generated from cast off years of leaf and needle litter. This leads to the next point—what makes a good mulch. Mother Nature uses leaves and needles—in the south, harvesters collect long needles from long needle pines and bale them. These needles are uniform and mostly clean of other organic debris and make an easy to spread mulch for a diversity of plant types. They break down well and really enhance the quality of the garden soil. Sadly pine needles are not commercially available in the northeast. In north western Vermont we typically use bark mulch, wood chip mulch, compost, or stone as mulch. They all have a place in the built landscape. Bark Mulch—hands down the most prevalent and popular mulch in Vermont. It is made from the bark of softwood trees shredded and ground to a uniform size. Typical “flavors” are hemlock bark mulch, pine-spruce bark mulch, and aged bark mulch. Great uniform product with a higher carbon to nitrogen ratio (higher C:N requires more nitrogen or more time to break down—to high C:N ratio can rob soil N away from plants). Perfect for mulching trees, shrubs, and acceptable for perennials. Wood Chip Mulch—least expensive mulch per unit. It is made from chipping up trees and limbs both hardwoods and softwoods. It can be high un-uniform containing all different sizes and shapes of chips and can contain shredded leaves and needles. It has the highest C:N ratio and can last for a very long time. Because of the C:N ratio and how well it can shed water this mulch has an excellent ability to suppress weeds. It also has a great ability for cushioning and is perfect for woodland walking paths and (if “clean” enough) excellent for underneath children’s playgrounds Compost—for most people this does not come to mind as a mulch, but it is!! It is made from biodegraded lawn and leaf debris and also can contain biodegraded animal manures. It has the lowest C:N ratio and can act like a light fertilizer for some plants. It does not prevent weeds as well as the others, but has great water management abilities. This is the best choice “mulch” for annual and perennial flower installations-particularly at establishment.
Stone mulch—definitely has more of an institutional feel, but can be a great low maintenance choice for commercial and some residential applications. Stone mulch requires fabric so that the stone doesn’t slowly get absorbed into the soil over time. It has great weed prevention and does help manage water loss and erosion. In addition to fabric stone mulch usually requires edging to keep the stones separated from the turf. This is a better choice for shrubs and trees in larger bed spaces in sites where maintenance is difficult. Stone has the highest labor cost at installation.
We’ve learned a little about what we mulch with, let’s discuss elements of how to mulch. Preparation is key—throwing down the mulch is the fun part, but preparation is what separates the professionals from the amateurs.
-Scrape out un-decomposed mulch from the beds. This is primarily the wood portion of the bark mulch mix. Mulch that is too deep can smother plants. Mulch that covers root flares and trunks of trees causes stem girdling roots and trunk rot. TREES BURRIED TOO DEEPLY IS RAMPANT. ALMOST ALL MULCH JOBS LOCALLY HAVE THE MULCH TOO DEEP AROUND TREES. Trees are an investment that grow and appreciate with time. Saving a few bucks on a cheap landscape maintenance provider who dumps and runs with the mulch can cost a fortune in tree removal and replacement down the road.
-Spade edge the beds. Putting a well-defined cut in the turf 3”-6” deep makes a nice definition between lawn and bed space and if maintained skillfully can keep grass from creeping into mulch beds. Clean up all of the edging debris—don’t bury sod chunks and edging swill under the mulch.
–Install a 2”-3” layer of mulch, being careful to not cover plant stems or root flares.
Mulching doesn’t simply involve dumping mulch into the beds every year. It takes thoughtful and skillful preparation to insure that your mulch is providing positive benefits and not short changing your long term investment.