Nellie Stevens holly has a natural pyramidal shape, so if left alone, it requires very little maintenance or pruning. However, many people prefer a neat sheared look, which requires regular pruning to maintain. There are several considerations to think about when planning when to prune Nellie Stevens holly. Hollies bloom on old wood, but hollies are not grown for their flowers. The berries, which develop in the fall and persist through the winter, are what people want to see. As long as you don’t prune too much of the old branches and only shear the new growth, the berries should grow just fine. Avoid pruning too late in the season, because it could trigger new growth that won’t have time to harden off before cold weather.