Although not essential to most plant species, silica plays an important role in the protection of plants against different types of stress. In monocots, the main role of silica is protection against herbivores. Although the mechanisms are not fully understood yet, it is clear that silica discourages the grazing of herbivores. Hence, high silica concentrations are unwanted in forage crops and grasses that are grown as a feed for ruminants. In this paper, we explored the possibilities to select forage grasses with a low silica concentration. In a yield trial comparing five forage grass species under cutting management, we found the highest and lowest silica concentrations respectively in tall fescue (Festuca arundinacea Schreb.) (0.7% averaged over all cuts) and perennial ryegrass (Lolium perenne L.) (0.35% averaged over all cuts). We found a negative effect of the silica concentration on digestibility of the organic mass (DOM). This effect was particularly strong in the first cut: − 4.9% points DOM per 0.1% points in silica concentration. In a screening of tall fescue nurseries for silica concentration, a range between 0.05% and 1.57% was found and there was a weak negative correlation between DOM and silica concentration. Based on a progeny test, a narrow sense heritability for silica concentration of 0.78 was calculated. Given the presence of both variation and a high heritability, selection for lower silica concentrations in tall fescue is promising. The simultaneous selection for DOM and low silica content offers good perspectives to improve the feeding quality of tall fescue.