All About Mulching: Types, Techniques, and When Not to Mulch

What Mulch Does

Modifies soil microclimate: conserves moisture, suppresses weeds, prevents erosion, buffers temperature swings.

Ideal Mulch Traits

Light, permeable to water/air, dense enough to block weeds.

Categories

• Organic: shredded bark, leaves, straw, grass clippings, peat moss. Cool soil, add nutrients.
• Mineral: gravel, crushed stone. Cool soil, permanent.
• Synthetic: plastic, geotextiles. Warm soil, excellent weed control.

Application Rules

1. 3–5 in. depth (more for coarse).
2. Keep away from stems/crowns.
3. Water after applying.
4. Trees/shrubs: 5–10 in. clearance from trunk.

Specific Materials

• Grass clippings: break down fast, add N. Avoid if herbicide-treated.
• Sawdust: low N, acidic—mix with compost; keep off alkaline-loving plants.
• Industrial by-products: brewery hops, mushroom compost, sawmill shavings.
• Compost: best mulch. Mix with coarse material for “living mulch.”
• Manure: well-rotted, blended with straw/clippings.
• Black plastic: lay first, cut X-slits, add side drainage slits.
• Mulch-mowing: shred leaves weekly with mower—free, builds soil.

When NOT to Mulch

• Seedlings in wet soil (damping-off risk).
• Waterlogged spring beds (crown rot).
• Low-lying, chronically wet areas.

Bottom Line

Mulch protects roots summer and winter, keeps soil loose, eliminates weeding, saves water. The single best garden habit.