We returned to the test site 19 days after establishing the plastic-covered area. During the trial, we checked the site occasionally for excessive heat, plant damage, or a moldy odor. We did not notice a moldy smell.
Condensation was visible on the underside of the plastic during most visits. The site received approximately 1.24 inches of rainfall during the treatment period. The surrounding compacted soil appeared to lose surface moisture relatively quickly, while the soil beneath the plastic appeared to remain moist for much longer periods.
During the trial, the average daily high temperature was approximately 75°F and the average daily low was approximately 50°F. Despite these generally moderate temperatures, the uncovered area showed little visible germination. The covered area developed a much denser stand.
The plastic treatment was the known intentional difference between the two areas. However, the plastic may have affected moisture retention, soil temperature, humidity, evaporation, airflow, and light. These individual effects were not measured separately.
Observations
The uncovered comparison area had very little visible germination, while the area beneath the plastic developed a visibly dense stand. Condensation was frequently present beneath the plastic, and the covered soil appeared to remain moist longer than the uncovered soil.
The result shows a strong association between the plastic treatment and improved germination. This trial did not isolate which part of the microclimate change produced the improvement.
Actions Taken
Removed the plastic sheet after 19 days so we could monitor whether the newly established grass continued growing under normal uncovered conditions.
Next Step
Photograph and compare the former covered area with the adjacent uncovered ground during the following weeks and months. Document whether the initial establishment advantage remains visible.