Living mulch suppresses weeds and conserves soil moisture.
A good hunch A person has checked it against its sources. If you skip this, it still grows, just less well. The planner suggests it.
How it works
A living cover keeps a leaf canopy over the ground. It intercepts light at the soil surface, so weed seedlings are shaded out before they establish, and it slows surface evaporation, so the soil holds more water. In a Three Sisters planting this is the squash's role. Its broad leaves shade the bed.
The evidence
Evidence: checked against 2 sources in the research-based literature.
The 2 sources
Studies show that mulch reduces evaporation from the soil surface and helps soil hold water.
The large, prickly squash leaves shade the soil, preventing weed growth
Plant teams that rest on it
- Carrot, chive and lettuce
- Melon Sisters
- Melon Sisters (small bed)
- Milpa
- Sweet-potato milpa
- Sweet-potato milpa (small bed)
- Three Sisters
- Three Sisters (small bed)
- Tomatillo pair
- Tomatillo pair (small bed)
Folklore it answers
Read next
- Do plants really affect their neighbors? Allelopathy, living mulch, and what the evidence supportsSome plants do change the ground for the ones beside them, and one will kill your tomatoes. The real effects look nothing like the companion chart.
- Controlling weeds, and the weed folklore that failsTwo habits beat everything: never let a weed set seed, and keep the soil covered. The mulch depths, the shallow hoe, the vinegar myth, and the weeds you plant yourself.
How this rule has changed
Every change is dated, newest first. The full record, with each reason, is in the data download.
- Sources updated
- Wording made clearer
- Sources updated
- A person read the sources and confirmed it
- Added to the rules
Plan a bed with Carrot, chive and lettuce ›
Companion planting charts encode real relationships. · What can I plant now?
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Cite this page
Milpa Gardens. “Living mulch suppresses weeds and conserves soil moisture.” Evidence grade: A good hunch. https://milpa.garden/rules/living-mulch-suppresses-weeds-conserves-soil-moisture/
A garden planner built on graded evidence. Every claim states its evidence grade and links its sources on the page. Cite it with the grade, and add the date you read it.
Report a problem with this claim
How we grade evidence
- Well established
- The rule names its mechanism and is settled, by sources a person has read and checked or by plain arithmetic and geometry.
- Promising
- The mechanism is named and the literature backs it. A few questions are still open.
- A good hunch
- Plausible by its mechanism, but field studies are thin, so treat it as a lean.
- Contested
- The evidence points both ways, or no study has tested it, so the planner does not enforce it.
- Refuted
- The claim did not survive its sources. It is kept so the folklore can be answered.