Stores are now awash with wood and bark chips. Besides the usual supply available at nurseries and garden centres, clean white bags of chips are also neatly stacked in front of hardware stores, supermarket, even convenience stores.
These piles of chips are feeding our springtime urge to spruce things up. Yet the benefit of chips can be more than just cosmetic.
Spread on top of the soil, chips break the impact of raindrops so that soil stays in place rather than washes away. Chips also are an effective insulator, protecting shallow roots from the heat of summer sun. In keeping the soil cool, chips slow evaporation of water from the soil so it stays more moist.
All the chips now on sale are testimonial to the fact that last year’s chips have gone away, decomposed. That’s not a bad thing, though, for decomposition releases plant nutrients and enriches the soil with humus.
Chips don’t need help
Some people spread a weed barrier of black plastic or landscape “fabric” over the ground, then top it with a thin layer of chips. Used in this manner, chips are purely cosmetic, their only function being to hide the ugly material underneath.
Besides depriving the soil of some of the benefits of chips, spreading chips over a permanent weed barrier leads to other problems. For instance, the barrier gets very messy if you ever want to move plants around. And it’s not really that good at permanently thwarting weeds, which start to creep into the chip layer on top of the fabric.
Worst of all is when the alleged weed barrier inevitably begins to peek through as the chip layer slides around. Then even the cosmetic benefit is lost.
Rather than using a non-decomposable weed barrier, pile chips right on top of bare soil or, if weeds are present, on top of paper or newspaper mulch, which eventually decomposes.
Chips don’t need bags
Some gardeners have the notion that chips sold in bags are superior to those made from locally chipped trees. One fear is that termites would infest wood other than cedar, which is often the wood source for bagged chips.
Termites feed on a variety of cellulose sources, including old roots, twigs and other material in and on the ground; a mulch of chips contributes insignificantly to the existing smorgasbord.
How about diseases spreading from those chipped, dead trees to the plants under which you spread the chips? This should not be a problem because most fungi that attack living wood cannot survive on dead wood, so would expire in the chips.
Fungi also are picky in just whom they will attack. So even if you spread chips from a diseased pine tree beneath your maple tree, your maple won’t get sick unless the disease survives in the dead chips; is capable of infecting maple as well as pine; and has conditions conducive to disease spread. You might as well worry about being hit by lightning on a sunny day.