In early spring, one of the first shrubs that I trim are my Firepower Nandinas.
By trimming them drastically, new growth emerges with a blast of new colors each spring and my plants never get leggy or show any winter damage. This is what they looked like before I retrieved my shears from the garage.
You can use a pair of pruners or sharp garden shears and remove all the growth except 4-6″ above the ground. Yes, all that will be left are woody stalks, but if you fertilize them generously with Professional Nursery Formula plant food, bright colorful foliage will emerge in 3-4 weeks.
My nandinas never show any signs of winter damage, they never get leggy, and the foliage is always attractive.
This is what they look like after I have finished my pruning.
This is what my Nandina Firepower looked like on April 23rd.