Killing Grass Naturally for a Gravel Yard: Plastic, Cardboard, or Just Gravel?

You want to convert a California lawn to gravel without chemicals. Two sheet-mulching methods: cardboard + mulch, or black plastic (+ mulch?). Questions: why mulch over plastic? How to know when grass is dead? Do you cut dead grass before laying weed barrier? Why kill grass first if you’re putting down a barrier anyway?

Black Plastic vs. Cardboard

• Black plastic (6 mil UV-resistant) blocks light, heats soil, kills grass/weeds in 4–8 weeks in summer. Mulch on top holds plastic down, reduces UV degradation, and looks better.
• Cardboard + mulch decomposes, feeding soil biology. Slower (3–6 months) but builds soil health.

How to Tell It’s Dead

Grass is dead when blades are brown, brittle, and roots pull up easily with no white, firm tissue. Dig a few test spots.

Do You Need to Remove Dead Sod?

If you lay a quality woven landscape fabric (not plastic sheeting) and 2–3 inches of gravel, you can leave dead sod in place—it becomes organic matter. The fabric blocks light; gravel protects fabric. Weed seeds will still blow in, so spot-treat emergents with glyphosate.

Simpler Approach

Mow low, lay fabric, gravel. Skip the kill step if you accept occasional breakthrough weeds. But killing first reduces long-term maintenance.