When I began making this new garden, I was able to get large quantities of bagged leaves and grass clippings free, so I used them to smother the lawn and to mulch around new plants. This year, I found a source of cheap wood chips, so I am employing them when mulch is needed.
Mulching with the wood chips this spring has prompted two “ahas.”
First, though a mulch of leaves creates great soil filled with worms and other beneficials, I’m noticing that leaf mulch tends to become dry and hot at the surface during Boise’s hot summer months, when lack of moisture drastically slows decomposition, whereas a layer of wood chips keeps a noticeably cooler surface temperature and retains more moisture at the soil surface. Plants that are struggling in sunny areas of my new garden (even those with a deep mulch of leaves) have perked up when I added a layer of wood chips.
This is different from my gardening experiences in Minnesota. There, mulching with leaves ensures cool, moist woodland conditions; they are the best materials for mulching trees and shrubs and their ground layer companions. Wood chips also keep the soil cool and moist, but don’t provide the nutrient boost given by leaves as they decompose.
My second “aha” is that I relax when a bed is mulched with wood chips. Is it that the wood chips are finer grained and more uniform than the widely varying “dinosaur poop” look of the bagged leaves? Is it that they smell fresh like a forest, rather than the mildewy or downright putrid smell when some of the leaves & grass clippings are released from their bags? Or am I responding to subtle signals of the plants, which are less stressed when mulched with wood chips?
Along with these ahas comes the not-new thought that, though I am a big fan of mulching, I view it as a temporary step in my garden’s evolution. Eventually, I’d like to achieve coverage of all bare ground with vertical layers of plants. Living mulch.