The dataset supports a larger study that examined the impacts of three tackifiers (guar, psyllium, and polyacrylamide) on growth of two dryland mosses (Bryum argenteum and Syntrichia ruralis). Moss fragments were grown in petri dishes and subjected to individual tackifiers in one of three possible concentrations (0.5x, 1x, or 2x) of the respective manufacturer's recommended application rate. Distilled water was used as a control treatment, giving a total of ten treatments (nine tackifier-concentration combinations and a water control). Bryum fragments were watered four times daily for six weeks and Syntrichia fragments were watered twice daily for five weeks, after which the experiments were concluded. Shoot length, shoot number, gemma presence, protonema presence, bound sand mass, and moss organic matter mass were all measured at the end of the experiments. This dataset reports mass adjustment ratios (average non-moss organic matter mass in milligrams per 1 milligram of bound sand mass) that were used to subtract non-moss organic matter mass from total organic matter mass measurements, ultimately calculating moss organic matter mass per fragment at the end of the experiment. Total organic matter mass was determined by placing fragments and attached substrate in a furnace and burning off organic matter. The post-furnace weight was subtracted from the pre-furnace weight to calculate total organic matter mass, with the remaining weight representing the bound sand mass. A separate experiment was performed without moss fragments, but with tackifier and sand, and subjected to the same furnace process to determine the proportion of total organic matter mass made up of sand organic matter and tackifier. Bryum and Syntrichia were grown on different sand types, which were composed of different amounts of organic matter and resulted in different adjustment ratios for Bryum and Syntrichia experiments.