The objective of this study was to com pare the effect of nonwoven fabrics used for growth acceleration in lettuce on the efficacy and selectivity of pendimethalin herbicide at varying application rates. Small plot experiments were conducted with head lettuce in Prague, Czech Republic during 2011–2013. Herbicide efficacy was higher in plots covered by nonwoven fabric, but selectivity was influenced negatively. Nonwoven fabric cover increased the efficacy of pendimethalin applied at rates of 600 and 1200gha−1. The highest efficacy was recorded against Chenopodium album (96–100%) and Amaranthus retroflexus (>90%). Efficacy against Echinochloa crus-galli ranged between 85% and 100%, against Solanum physalifolium between 77% and 100%, and against Mercurialis annua between 72% and 99%. Selectivity of pendimethalin to lettuce was lower in 2014, when intensive precipitation was recorded during the growing season. Lettuce injury (15–27%) was recorded on plots covered by nonwoven fabric treated by pendimethalin at a rate of 1200gha−1. The effect of pendimethalin on lettuce yield was not significant. Changes in photosynthesis rates can be assigned more to the effect of fabric coverage than to that of pendimethalin. The values obtained were affected both by the density of stomata as well as their distribution on leaves, and these vary in response to environmental conditions.