Until recently, I wasn’t a big mulcher. I was confused by how to apply it in our small, densely planted space. I was daunted by the prospect of stockpiling large amounts of organic matter each year. I made a few attempts, but didn’t really get it.
Until this summer. With our current stage 3 watering restrictions, we’ve had to find ways to get by with less irrigation. Now, I’m a mulching convert, singing the praises of this highly beneficial practice.
Mulching is the application of a layer of protective material on top of the soil. What that material is made of can vary greatly, from straw to compost to plastic. In all cases, mulch acts much like the fiberglass insulation in a house, keeping your garden cool in the summer, warm in the winter, adding nutrients and preventing water from escaping.
The few rainy days we’ve had recently won’t be enough to solve B.C’s current drought. We need to continue to do everything possible to reduce our water use at home and in the garden. Mulch is one of our most powerful tools to achieve this. By slowing the process of evaporation, a well-mulched garden requires far less watering than a non-mulched garden. In my experiments at home, our mulched beds can get by with a thorough hand-watering only once every few days. Bare soil dries out far more quickly.
Straw is one of the most commonly-used mulch materials on sustainable farms. It’s attractive and easy to spread around plants. In a rural environment, straw is easy to come by. In the city, however, it can difficult to find, costly, and require transporting by car.
As urban gardeners, we often need to be crafty and use non-traditional methods that are appropriate for a city scale. When it comes to mulch, there are a number of options that can be found easily and for free. Layers of hand-torn newspaper or cardboard are an effective option. The inks used these days are generally safe, and newsprint comes without the danger of pesticide residue presented by some straw. Leaves are another good choice. I’ve been known to surreptitiously rake my neighbour’s lawns in the fall in order to save up materials. Just avoid oak and walnut leaves, which contain chemicals that slow the growth of other plants.
One of my favourite mulch materials this year has been compost. Pea plants that have stopped producing, the midribs of kale leaves, carrot tops — all of it gets chopped up with clippers and spread on my soil, as long as it’s free of pests and diseases.
Mulch is used extensively on sustainable farms, where there is plenty of space and easy access to materials like straw. But how does that translate to an urban situation? After some trial and error, here’s what works for me.
HOW TO MULCH YOUR VEGETABLE GARDEN
- Apply at least a couple of inches of mulch, the more the better, anywhere you see bare soil. The mulch should be too thick to see through.
- Avoid smothering your crops by leaving a bit of space around the stem or crown of each plant.
- Mulch is highly attractive to woodbugs. Although most woodbugs are helpful decomposers, they can sometimes munch on tender young seedlings. For this reason, I like to wait a week before mulching around newly transplanted crops.
- Mulch can be used with all plants, but is especially effective with big summer and fall crops like kale, tomatoes and squash. I generally don’t use mulch around delicate and densely planted spring greens, like mustards, radishes, scallions and arugula. It’s just too hard to find the space around those tiny plants, and during the wet spring months, mulch can be a potential hiding spot for slugs.
- Mulch is most effective when used in raised beds, but go ahead and experiment with using it in pots.
- In addition to saving water, mulch does wonders to prevent weeds, and can be used in the winter to warm the soil.