In Florida, the timing for cutting back fountain grass (Pennisetum) varies depending on your specific location within the state. In southern and coastal regions with milder winters, it's typically done in late winter or early spring, around February or March. In central and northern Florida, where occasional freezes are possible, it's advisable to wait until late winter or very early spring, around March. These timings strike a balance between protecting the grass from potential frost and preparing it for new growth in the upcoming season. However, local microclimates and weather patterns can influence the exact timing, so observation of the grass and local conditions is key.