Mulch Mania: Building a foundation for a low-maintenance garden

A temporary alternative to natural ground cover

Good or bad, we all remember the gardens of our childhood.

I remember dry, barren earth that literally turned to sand when you held it in your hands. It was the 1960s and the only plants that grew in the front gardens were traditional purple iris.

Not that my parents didn’t try. They turned over the soil religiously revealing the darker damp soil for a few hours until the sun baked it again.

It’s hard to imagine a worse recipe for building high-quality, healthy soil. But they toiled on, sometimes adding peat moss or top soil. The ending was always the same. Dry, bleached and baked sandy soil.

The missing ingredient was, of course, mulch. I am sure it was available at that time, but it certainly wasn’t piled up in bags at every building supply, grocery and nursery store.

A natural mulch of fallen leaves is not only beautiful, but acts like a cover for plants, insect and small animals throughout the winter months.

Today, cedar mulch is so common in our area, it’s hard to believe there are any cedar trees still standing.

Organic mulch is commonly made from bark or wood chippings, but it can also be made of grass clippings or pine needles (a popular choice in parts of the United States,) to name just a few.

Non-organic mulch is another option and another blog post but includes stone such as pea gravel, aggregates and man-made substances.

Cedar mulch is a forest byproduct made from the shredded wood of cedar trees. Compared to pine mulch, the inherent nature of cedar makes it a longer-lasting mulch in the garden.

The benefits of mulch far outweigh any argument for not using it. Not only is cedar mulch attractive, whether you choose natural-, black-, brown- or red-coloured, it has a pleasant smell for the first few weeks it is put down, helps unify the garden and better shows off the plant foliage.

Despite its obvious benefits, it’s still not unusual to see uncovered, baked earth on my daily walks, usually accompanied by the homeowners on their hands and knees pulling weeds or, God forbid, turning the soil over so they can enjoy a few hours of dark soil before the sun comes out to bake it beige again.

Mulch is the perfect backdrop for the foliage of this Pagoda dogwood, while it protects and insulates the soil below. Over time it breaks down and adds a woodsy organic material to the soil.

In many ways, mulch actually takes the place of a living ground cover.

And, although bark mulch is a great beginning to amending your soil an creating a more woodsy soild, it’s best not to consider it the finished product.

In a woodland garden, a native and natural ground cover such as wild geraniums, bunchberry or ferns are a more desirable alternative than organic mulch, but there are plenty of situations where a ground cover is not feasible at the time.

That’s where an organic mulch truly shines.

Without going into all the benefits of heavily mulching your gardens, let’s examine just a few of the reasons mulch should be high on your list when you are building your Woodland garden.

Water retention: By shading the soil with a thick layer of mulch (ideally 3 inches or more), evaporation, both from the sun and wind, is minimized.

It also helps to regulate the temperature of the soil further reducing water evaporation and giving the plants a layer of insulation that helps keep the plants’ roots cool in the summer and warm in winter.

Wood mulch is used here to cover the ground around woodland plants including bee balm and ferns.

It is important to note, however, that mulch can also act as a barrier that makes getting sufficient water to your plants’ roots more difficult. It is much more water-efficient to target the plants individually either through a drip system or by hand watering them individually.

Deep watering a plant by leaving the hose dripping at its roots for several hours will allow the water to dive deep into the ground rather than getting locked into the mulch layer or just licking the top inch of the soil.

If your garden is properly mulched, you need to water less often but when you do water, ensure you are deep watering and targeting the plants’ roots.

One of the often overlooked benefits of mulch is that it helps prevent water runoff by trapping the moisture and moving it slowly to the soil below.

During a major storm, for example, water that might traditionally just run off in one direction, flooding one area and leaving another area more or less dry, will be better constrained to the general area it fell on. The result, a more evenly irrigated garden that will retain the moisture much longer than barren earth – possibly days or even weeks.

Weed Inhibition: Everyone is striving for a low-maintenance garden. Mulch is the key ingredient to achieving that end. But, let’s not kid ourselves it can’t perform miracles, especially if it is spread too thinly over the soil.

We’ve all seen it. A layer of mulch so thin that you can see the soil through it. Using large pieces of bark rather than the shredded bark, is often the biggest culprit here.

Unlike the shredded mulch, or pine needles, the bark pieces are too large to properly cover the soil and the resulting gaps make it too easy for seeds to find their way to the soil. (If you really love the look of the larger bark pieces, consider using the shredded mulch as your primary covering and top dress with the larger pieces.)

if the ground is not covered properly, once the weed seeds germinate, pulling them out brings more soil to the surface and before you know it, your garden is covered in weeds.

Here is a good example of natural wood mulch being used to cover the ground while our native virginia creeper gets a chance to establish itself as a living ground cover or mulch.

The key is to block light from reaching the soil to keep the seeds from germinating.

Some seeds will germinate right in the mulch but without proper soil they are either not long-lived or easily removed because it is near impossible for them to get properly rooted in the bark medium.

Also, if you water your individual plants rather than a general watering of the entire garden, the weeds’ roots often eventually are starved of water and die off. This is especially true following a wet spring. Weeds from the previous year will sprout in the damp mulch left by snow cover, but as the mulch dries out, the seedling roots will often die off.

A common complaint against the use of cedar mulch in the garden is that it can deplete the amount of nitrogen in the soil. While this can be true, it is not something most homeowners should be worried about.

What is more worrying is the practise of piling mulch around trees and plants in a volcanic mound that is almost guaranteed to kill the plant over time.

I often see it done by unknowing city workers who like to pile mulch up the tree’s trunk as high as possible thinking they are conserving water. Do not fall into this trap. Roots of trees and plants do not benefit from mulch touching them in any way.

Keep the mulch away from the plants and, instead, create a bowl of mulch around the tree trunks or plants where the sides can hold the water or at least slow its runoff from around the plant or tree. The bowl should be larger according to the size of the tree or plant and can actually extend out to the drip line of a young tree or plant.