Mulching with Aggregate

Rocks, gravel - Some homeowners use inorganic mulch materials such as gravel, pebbles, lava rock, or crushed rock. They may seem like as good of a choice as mulch, since they will not decompose. They do not require annual replacement but pose some potential drawbacks. Be certain the material is compatible with the overall landscape design. They are well suited for a rock garden, herb garden, or Japanese design but may not be appropriate for a perennial flowerbed or a foundation planting.

In addition to the extra time it takes to apply these materials, some consideration should be given to problems associated with replanting shrubs or removal of these mulch materials. Keep in mind that organic matter will over time fill the voids of the rocks, which will be an opportunity for weeds to germinate. Unlike mulch, aggregate adds no nutrients to your soil and will tend to compact it, too much compaction will make it difficult for your plants to root out.

Light coloured materials will reflect sunlight and cause the temperature around the plants to be warmer. Rock mulch absorbs heat during the day and releases the heat at night thus increasing water loss. Avoid using rock mulch around plants that might not grow well under these conditions.

A border of some type should be applied to keep the material in place; otherwise you may end-up with rocks in the lawn or on the driveway and sidewalk. When leaves and other debris fall into rock mulches, they could be difficult to remove.