The objective was to evaluate the effect of intervals of irrigation frequency (water deficit) in the development of cover crops. The experiment was conducted in a greenhouse at the experimental campus of the Federal University of Piaui (UFPI) in Bom Jesus-PI in the period between June to August 2011, on soil classified as Typic Dystrophic - Lad. The experimental design was randomized blocks in factorial scheme 5 x 4, with factors consisting of 5 cover crops (Brachiaria brizantha cv. Piata; Mucuna aterrima; Pennisetum glaucum cv. ADR-500; P. glaucum cv. ADR 8010; Brachiaria brizantha cv. Marandu), and 4 intervals of irrigation frequency (2, 4, 6 and 8 days), with 4 replications. Cover crops were significantly affected in their development, with reductions in biomass above 50% when subjected to the interval of irrigation frequency to 8 days. The P. glaucum cv. ADR-500 has potential to overcome the water deficit conditions during the off season in the Cerrado of Piaui. Key words: Brachiaria, Pennisetum glaucum cv. ADR-500, no-tillage.