Spring is the time to tackle your ornamental and native grasses. Grasses begin to grow at varying times depending upon the Genus. They grow and flower and produce the seed heads that remain attractive in summer, fall, and have become an important design element in the winter landscape as well.
In spring, before new growth begins, cut all of your grasses down to just a few inches above the ground - you want to remove all of last year's foliage to allow the new growth to emerge from the crowns.
Cool season grasses (like Karl Foerster reed grass) will start to grow right away, and the warm season grasses (like Switch Grasses or Flame Grasses) will not show signs of life sometimes until June, so just be patient as the soil needs to warm up more until you will see growth. If your grass clumps have gotten too large across, they should be divided to keep them vigorous and healthy. Spring is a good time to divide your grass clumps. Just remember, It is important to cut the old foliage before the new blades begin to emerge.