Mulch
Also known as: ground cover mulch
Mulch is any material spread over the soil surface to retain moisture, suppress weeds, moderate soil temperature and reduce erosion. Common organic mulches include bark, wood chips and shredded wood.
In simple terms
Mulch is the layer you spread on top of soil around plants. It keeps moisture in, blocks weeds, and protects roots from heat and cold — and it makes beds look finished.
In depth
Mulches divide into organic (bark, wood chips, shredded wood, straw) and inorganic (rock, rubber). Organic mulch breaks down over time, feeding the soil but needing periodic replenishment; inorganic mulch is permanent but does not improve soil. A 2–3 inch layer is the sweet spot: enough to block light and hold moisture, but not so deep it suffocates roots. Keep mulch a few inches back from trunks and stems to prevent rot. In hot, dry summers, mulch dramatically cuts irrigation needs by slowing evaporation.
Why it matters
Mulch is the highest-impact, lowest-cost thing you can do for plant health and water savings — it can cut soil evaporation substantially during the region’s long dry summers.
Common mistakes
- Piling mulch against trunks ("volcano mulching"), which traps moisture and causes rot.
- Spreading too thin (weeds break through) or too thick (roots suffocate).
Examples & uses
- Around trees, shrubs and in planting beds.
- Weed suppression in low-maintenance areas.
- Moisture retention for vegetable gardens.