What is mulch?
Mulch is material that is put over exposed soil as a protective covering. Mulch can be applied over your garden beds and around plants, shrubs and trees.
Why only approved plants and permeable mulch?
Using permeable materials, such as bark nuggets and wood chips, for mulch in home landscape design helps to conserve water, prevent flooding, erosion and stormwater pollution, control weed growth, moderate soil temperature, and improve overall soil quality.
Likewise, using drought-tolerant and native plants in landscape design aids in water conservation, lower maintenance, supports biodiversity and prevents stormwater pollution.
Why use mulch?
- Conserve water – mulch slows evaporation and helps soil retain moisture, which means watering less often.
- Prevents flooding – by improving soil’s ability to retain moisture, mulch also helps prevent floods during heavy rainfall events.
- Prevents erosion and stormwater pollution – mulch helps protect your topsoil from being washed away by rain and wind. This also helps prevent your topsoil from being washed into storm drains and polluting the river.
- Control weed growth - mulch deprives weed seeds of light to help keep them from sprouting and gaining energy to push through the mulch
- Moderate soil temperature – mulch insulates the soil - and therefore your plants - from extreme hot and cold
- Improves soil quality – over time mulch materials such as cardboard, grass clippings, leaves and wood chips will break down and add to soil structure, thereby helping to reduce compaction, retain moisture and provide necessary nutrients to plants
How to use mulch
- Though you can apply mulch anytime, a good time to apply new mulch in the spring when ground has thawed but isn’t waterlogged.
- Weed beds thoroughly before applying mulch; putting mulch over existing weeds won’t necessarily smother them. If you know the space is filled with weed seeds or perennial roots, cover it with a layer of plain cardboard, newspaper or biodegradable fabric and top it with more visually appealing mulch.
- Apply between two and four inches of mulch. You need that much to get the benefits, but more than four inches can deprive soil of oxygen, which is bad for your plants’ roots and for the beneficial microbes living in the soil.
- Keep mulch at least three inches away from the base of any plant, shrub or tree. “Mulch volcanoes” around the bases can lead to problems with insect and rodent infestation, and excess build-up of material and moisture around the base of the plant which can lead to tree trunk and plant crown rot.
- Turn decayed mulch into the soil with a tool like a garden weasel or a pitchfork before reapplying new mulch to avoid compaction and build soil.
- Replenish mulch as needed to keep it between two and four inches deep.
- Dampen the mulch if it is at risk of blowing away.
- Ensure that mulch is not installed close to the street or alley way. Mulch may run off during heavy rainfall or wind events, entering and clogging storm drains and polluting the Red Deer River.