Hi! I’m looking for the best mulch for my flower beds, in terms of keeping moisture in, weeds out and keeping the soil healthy. Mostly I have shrubs, i.e. Annabelle and Peegee hydrangeas, emerald cedars, lilacs, bleeding hearts, hostas, ferns. I have both sunny and shade areas. In the past I’ve used Nincompoop, which I love because it’s an organic mulch that looks like top soil. It’s expensive and hard to find, and not available in Toronto. Last year I used black cedar mulch, which is affordable. Do I need to mulch every year? Should I put compost down before adding the mulch?


Thank you for contacting the Toronto Master Gardener.

There is a difference between compost and mulch. Compost is nutrient rich and full of life that improves the soil and feeds roots. Mulch on the other hand is used to keep consistent moisture and keep weeds down. It insulates the soil,helps prevent erosion and helps protects your tender plants during the winter. You cannot use mulch in place of compost however you can use compost as you have done in place of mulch.

The benefit of using compost, as mulch is it is nutrient rich, and as it rains or snows it will leach nutrients into your soil and beneficial bacteria into your soil naturally (without tilling). In my own garden I tend to use compost as mulch since my garden is quite large this saves me time from applying both compost then mulch. If you decide to apply both compost and mulch, the compost should be applied first then the mulch. There are different types of mulch and depending on the type you purchase will determine how often it needs to be applied.

Composted cedar is relatively inexpensive and is quite popular. Natural shredded cedar mulch decays into the soil after a couple of gardening seasons. Since natural cedar decays into the soil after a couple of gardening seasons, you may consider working both the compost and mulch into the soil followed by a new layer of mulch.

Composted pine bark mulch is processed from pine bark and is usually composted for two years. Like cedar mulch, this mulch decays very slowly and has a long beautiful lasting natural brown colour. Over time as the material decays and becomes incorporated into the soil it will improve the soils ability to retain moisture along with increasing the organic content of the soil.

If you property contains a large number of trees you might consider using leaf mulch next fall.Leaves contain around 80% of the tree’s nutrients including carbon, potassium, and phosphorus. Before adding leaves to your garden bed be sure to shred your leaves. Whole leaves can pack together and make a fairly solid mat which rain cannot penetrate. If you don’t own a leaf shredder run them over with a lawnmower a few times. This link provides a list of mulches listing the pros and cons of each.

You can apply mulch once the soil has warmed up and dried up from the winter. Make sure to weed the area before applying 4-5cm of mulch. As always when applying mulch, ensure the mulch does not touch the crown or stems of your plants to avoid rot caused bu the moisture-retentive quality of the mulch. Leave approximately 2.5cm around the plant.

In my experience, if you add compost and mulch every year your beds will become higher than the lawn, which sometimes leads to water, run off.

Happy mulching!