The Miracle of Mulch

I believe that 90 percent of our gardening success is rooted in proper ground preparation. Without a doubt mulch is a major part of that. Mulching is so beneficial and serves so many different purposes that it is hard not to make it my number one garden rule.

Studies have shown that mulching reduces evaporation from the soil by 10 to 50 percent. Evaporation can be particularly high in hot, dry and windy conditions, but can be a problem in all gardens. Mulch keeps moisture in the soil so there is much less lost to evaporation. Mulch can also help if too much water or rain is a problem. It will improve poorly draining soil over time, and you can plant directly into some organic mulches rather than in the soil, so your plants don’t have wet feet during a rainy spell.

Insulation for your garden

The “insulating” effect of mulch is often overlooked even by experienced gardeners, yet it can be a real lifesaver for your plants, particularly shallow rooted perennials.

A layer of mulch keeps the soil cooler on hot days and warmer on cool days, meaning more gradual shifts in soil temperature. Mulch also minimizes freeze-and-thaw cycles, in which the frozen ground thaws, absorbs moisture from melted snow or rain, and then freezes again in a cold snap. The refrozen earth is now filled with ice crystals, causing the ground to heave, forcing plants out of the soil or exposing roots.

As spring rolls around, moist mulch will delay the warming of the ground. This may sound counterproductive, but it can save plants from coming out of dormancy too soon, just as one last late spring freeze hits. In summer, mulch can keep the ground cooler by as much as 6° C (11° F). This is particularly useful in very sunny, hot spots in the garden where high soil temperatures can damage the roots, especially of shallow-rooted or newly planted plants. Alternatively, dark organic mulches warm up the soil. In spring, this gives plants a quicker start and, in summer, it will benefit vegetables as well as plants in cool spots in the garden.

Shredded bark mulch

My favourite mulch is shredded pine or cedar bark.

Apply six to eight centimeters (two to three inches) of this all natural mulch over the surface of the soil in any part of your garden. It knits together when dry, isn’t washed or blown away and it smothers weeds very effectively. Once spread, the fibres knit together, forming a blanket that stays in place but still allows water to percolate through. After two to four years, it will begin to break down, adding valuable organic matter to the soil. At this time, you simply spread another layer over the bed.

An even and thick layer of mulch will help to reduce weeds in the garden. It allows your garden plants to compete with weeds and makes it easier to remove those weeds which do appear.  Mulching can reduce weeding by up to 95% in the first year.

Heard enough? Fact is, it does not matter what growing zone in Canada you live in, mulching provides many benefits. Perhaps the main one is providing you with more time to do the things you enjoy, whatever they may be.

Keep your knees dirty!

Mark

Mark Cullen appears on Canada AM every Wednesday morning at 8:40.  He is the Lawn and Garden expert for Home Hardware.  Sign up for his free monthly newsletter at www.markcullen.com.