Spring is well underway here in New England and all throughout local neighborhoods and businesses many landscapers are out applying a fresh layer of mulch to the landscape. Nate asked me to write a short piece on mulching and why it is a good investment for your landscape.
Why do we mulch Landscapes?
1. CosmeticsAfter the long New England winter we are all eager to see a fresh addition of color to the landscape. Even if you are mulching with black mulch or compost the fresh new material adds a nice new level of definition to the garden. Couple that with a fresh new spade edge and everything looks all crisp, fresh, clean, and ready for the new season.
2. Sound HorticultureIn native systems, plants self mulch with layers of leaf litter and sloughed off tree bark. Over time this discarded organic material forms a duff layer that is a perfect, organically enhanced, root zone for the plants. In addition to providing and storing nutrients, the duff layer helps protect the roots from climactic extremes both hot and cold. Mulching in the landscape serves much of the same purpose, but because how our cultured landscape relates to structures, walkways etc. We cannot allow the continuous accumulation of mulch and/or organic debris. This is important because a good mulching contractor will pull off the layer of least decomposed mulch to help the planting sustain a “duff” layer of about 2"-4". Good mulch installers also do not use weed fabric as this inhibits the mulch’s ability to amend the soil. Wood or compost mulches over weed fabric are simply cosmetic in nature.
What Makes Good Mulch?I should discuss at this point what makes good mulch. The most popular are wood mulches, rock mulches, pine straw, and compost. Each mulch has its place and its pros and cons. In New England, most prefer the wood bark mulches—particularly those made of hemlock bark or pine bark. One thing to remember with wood based (bark) mulches is that adding wood to the soil severely adjusts the carbon-nitrogen ratio heavily in favor of the carbon. The decomposing wood robs nitrogen from the plants—if you repeatedly mulch with very woody mulches supplemental fertilizer is necessary to combat this removal of nutrients. Rock mulches are nice because if installed correctly they are more or less permanent. You do need to lay weed fabric under stone to prevent the stone from just sinking into the mud and being lost. With rock mulch, however, you lose the soil amending aspect of organic mulches. Rock mulch also creates difficulty with adding to or changing a garden. Pine straw is hugely popular in the southern US. It is inexpensive and spreads quickly. It is tremendously positive for gardens and landscapes and does not have a high carbon to nitrogen ratio making it easier on stored nutrients than wood mulches.
Compost is common "mulch" here in northern Vermont particularly for perennial gardens. It contains nutrients and does a wonderful job enhancing the soil. You do have to be careful because compost can contain weed seeds and it also provides a very hospitable environment for weeds to germinate.
3. Water ManagementMulch is important for your landscape plants as it helps prevent soil moisture loss. We are living in a changing climate and one of the results is more drastic weather events. We are seeing longer periods of rain followed by extended periods of drought. Our average precipitation is remaining constant, but we are receiving more of the precipitation in fewer rainfall/snowfall events. Mulch plays an important role in preventing soil erosion (dispersing the energy of falling raindrops) and helping hold moisture at the plants’ root-zone.
Landscaping with mulch is critical in this ever-changing climate.