When determining which garden mulch or landscape mulch is best suited for your landscaping needs, there are many factors to consider. The question can best be tackled by presenting the various garden mulches or landscaping mulches separately, but judging each based on the same criteria.
Before beginning, first take a look at a preliminary question that many landscaping enthusiasts have: How does landscape mulch affect soil pH? More specifically, does any garden mulch lower soil pH, as many have long suspected?
Soil pH and Landscape Mulch
The composition of your soil pH has a hefty impact on plant health. Since garden mulch could influence that composition as it decomposes, it’s understandable that people have often expressed concern over how garden mulch selection impacts soil pH.
The most widely held view at present seems to be that garden mulch has little impact on soil pH. For instance, while oak-leaf garden mulch may be acidic when fresh, most experts now say that it becomes more and more alkaline as it decomposes. Furthermore, it is now generally thought that garden mulch composed of pine needles lowers soil pH to only a negligible degree, if at all.
With the question of the potential impact of garden mulch on soil pH out of the way, you should now reflect on some other issues surrounding garden mulch selection—some of which are quantifiable, others of which boil down to personal landscaping preferences.
You will have to prioritize in order to make a decision, since garden mulch that scores high in one category might perform miserably in another. Two obvious uses of garden mulch to which the reader will find little or no reference in this article are weed suppression and erosion control. They have been omitted for a simple reason: Any garden mulch employed properly will cut down on weeds and erosion. These are the two constants in this discussion.
Uses of Landscape Mulch
The uses of landscape mulch are not limited to weed control. Among the other uses of landscape mulch is as an agent to control erosion. Landscape mulch applied in the fall keeps the severe weather conditions of winter from eroding your soil and robbing it of valuable nutrients.
By insulating the frozen soil from the sun’s rays on that odd mild day in the winter, you’ll help your plants maintain the protective state of dormancy that they’re in. As a bonus, when the landscape mulch decomposes, it will release valuable nutrients into your soil.
Landscape mulch also improves moisture-retention in the soil, cutting down on your water bill in the summer.
Quick Notes about Landscape Mulch
"Insulation value in summer" is judged by the degree to which the garden mulch can keep the soil beneath cool and moist. A successful summer insulator will both reduce the need for watering and protect roots against extreme heat.
The consideration of whether or not the garden mulch needs to be removed in spring is grounded in the fact that heavy organic garden mulches can smother emerging spring plants. This is obviously less of a factor, however, for plants that remain alive aboveground, throughout the winter.
Even plants that remain aboveground can profit from having the soil around their roots warmed by the spring sun, a process facilitated by the temporary removal of the garden mulch. In the case of plastic sheet mulch, this factor is irrelevant, since holes are poked through the material to provide access for the plants.
"Nourishment and aeration afforded to underlying soil by decomposition" is one of the criteria used in the following pages to compare the various landscape mulches. However, do not be fooled by the word "nourishment" into thinking that compost and garden mulch are synonymous.