Gardening glossary
Mulch
Mulch is any material — organic or inorganic — laid over the soil surface around plants. A good 2-4 inch layer does four things at once: it slows evaporation, blocks weed seeds from sprouting, buffers soil temperature against heat spikes and cold snaps, and reduces soil splash that spreads fungal disease onto leaves.
Organic mulches are the workhorse choice for most beds: shredded bark, wood chips, straw, pine needles, cocoa hulls, leaf mold, and grass clippings. They break down over a season or two, feeding earthworms and microbes and adding organic matter to the soil underneath. The trade-off is you'll top them up every year.
Inorganic mulches — gravel, pebbles, landscape fabric, rubber chips — last longer but contribute nothing to soil biology. Gravel works well for Mediterranean herbs and succulents that hate damp crowns; landscape fabric belongs only under hardscape, not in planting beds where it suffocates roots over time.
How to mulch correctly: - Pull mulch back 2-3 inches from stems and tree trunks. "Volcano mulching" against bark invites rot and rodents. - Apply after the soil has warmed in spring (cold, wet mulch in early spring delays warming for heat-loving crops). - Water the bed first, then mulch — you're locking moisture in, not keeping it out. - For vegetable rows, straw or shredded leaves are cheap and easy to rake aside at season's end.
Avoid fresh wood chips dug into the soil — they temporarily tie up nitrogen as they decompose. On the surface, that's a non-issue. Around hungry plants like tomatoes or roses, top-dress with compost first, then cover with mulch.