Mulch is one of those garden tasks that looks simple, and mostly is. But there's a short list of things people get wrong that can quietly undo all the good work. If you've ever wondered whether you're doing it right, or you're mulching for the first time this season, here's what actually matters.
What is mulch?
Mulch is any material spread over the surface of your soil to protect it and improve growing conditions underneath. It acts as a barrier between your soil and the elements, holding in moisture, keeping roots cooler in hot weather, suppressing weeds, and breaking down over time to feed your garden naturally.
There are several types of mulch, but cedar is by far the most popular choice for Ottawa/Gatineau and the Valley gardens. Its natural oils help resist insects and decay, it breaks down slowly adding organic matter to your soil, and it holds its colour longer than most alternatives.
Why cedar mulch works so well
Cedar mulch does a few things better than most alternatives. Its natural oils act as a mild insect deterrent; it breaks down slowly, so you're topping it up rather than fully replacing it; it holds its colour longer than plain wood chips; and it has a clean, pleasant smell that doesn't overpower your garden.
We carry two options at Mountainview:
- Natural Shredded Cedar Mulch — the classic choice, blends naturally into garden beds and works with any planting style
- Black Shredded Cedar Mulch — the same cedar, dyed for a bold, high-contrast look that makes plants pop
Both are available by the cubic yard bag or cubic yard load, depending on how much ground you're covering.
When to mulch in Ottawa/Gatineau & the Valley
The ideal window is mid to late spring, once the soil has had a chance to warm up. Mulching too early traps cold soil and slows down plant growth.
That said, if you're reading this in July and haven't mulched yet, it's not too late. Mulching in early summer still gives your garden real protection through the hottest weeks of the year, when moisture loss and weed pressure are at their peak. The window is longer than most people think.
How to mulch properly, the right way
Getting mulch down right comes down to a few key details:
- Weed first. Pull any existing weeds before you mulch. Mulch suppresses new weeds from germinating, but it won't kill what's already there. It'll just hide it.
- Aim for 2-3 inches deep. This is the sweet spot. Too shallow and you lose the weed suppression and moisture retention benefits. Too deep and you risk trapping excess moisture at the soil surface, which can lead to rot.
- Keep it away from stems and trunks. This is the most common mistake. Mulch piled against plant stems or tree trunks, sometimes called "volcano mulching", traps moisture against the bark and creates conditions for rot and disease. Leave a gap of at least 2-4 inches around the base of every plant.
- Don't bury your edging. Keep mulch contained to the bed. Spreading it across lawn edges creates a messy look and makes maintenance harder.
- Refresh, don't always replace. Cedar mulch breaks down slowly. In most cases you can top up an existing layer rather than removing everything and starting over. Rake the old layer to loosen it up before adding new mulch on top.
Mulch hacks worth knowing
A few things that make a real difference without much extra effort:
- Water before you mulch. If your soil is dry, give it a good soak beforehand — the day before is ideal, but right before works too. Mulch locks in whatever moisture is already there; starting with dry soil means you're trapping a deficit.
- Layer compost underneath. For beds that need a boost, spread a thin layer of compost directly on the soil before mulching. The mulch holds it in place and slows evaporation while the compost works its way down.
- Go thicker in vegetable gardens. Between rows, you can go up to 10 cm. Foot traffic compacts mulch faster here, and the extra depth helps with the heavier watering demands of vegetables.
Frequently asked questions about mulch
How often should I add to my cedar mulch?
Cedar breaks down slowly. In most Ottawa/Gatineau and the Valley gardens, a top-up every one to two seasons is enough. If the layer has compressed below 1-2 inches, it's time to refresh.
Can mulch attract pests?
Cedar's natural oils make it one of the more pest-resistant mulch options available. As with any mulch, keeping it away from your home's foundation and plant stems reduces any risk further.
Is it better to mulch in spring or fall?
Both have value. Spring mulching conserves moisture and suppresses weeds through the growing season. Fall mulching insulates roots through winter and breaks down to feed your soil by spring. If you can only do one, spring is the higher-impact choice.
How much mulch do I need?
Measure the length and width of your bed in feet, multiply them together, and then divide by 100 to estimate the cubic yards needed at a 2-3 inch depth. When in doubt, round up. Leftover mulch can always be used elsewhere.
What's the difference between natural and black cedar mulch?
Both are shredded cedar with the same functional properties. The difference is purely visual — black cedar is dyed for a bolder, more defined look in garden beds.
Every lawn and garden project is a little different, and we like it that way. If you're not sure how much mulch you need or which type fits your space, our team is happy to help. Just reach out. And if you're picking up mulch this season, don't forget that we carry everything else your garden might need too: compost, topsoil, grass seed, and our new all-natural Acti-Sol fertilizer, because healthy gardens start with healthy soil.
