Trim these conifers when they are actively growing by Bert Cregg Length: 04:44Length: 4:44Pines (Pinus spp. and cvs.), whether they are trees or shrubs, should be pruned during active shoot growth because this will allow sufficient time for the shoot to produce a new set of buds for next year’s growth. The current year’s new shoots, or "candles," can be cut with hand pruners or pinched off to the desired length. Learn how to prune evergreen pines in this video with Bert Cregg, an associate professor in the horticulture and forestry departments at Michigan State University. View the discussion thread.