This study was conducted to evaluate the effect of pruning frequency and fertilization on yield, digestibility, and mortality of two varieties of king grass (Pennisetum purpureum), green and purple. The experiment used was a randomized block design with a split-plot arrangement and six repetitions. In the sub-subplot a pruning frequencies of 10, 14 or 17 weeks in 25 m² were assigned. In the statistical analysis performed for biomass yield no difference was found between the two varieties, but there was difference between fertilization levels and between pruning frequencies, the more productive being 17 weeks. There was increased mortality of plants when not fertilized due to high intensity pruning in the first 10 weeks. For the in vitro digestibility of dry matter differences, differences were found between varieties and between pruning frequencies with values of 75.3 %, 72.2 % and 72.4 % for pruning at 10, 14 and 17 weeks, respectively, with the 10 week frequency different from the others.