It steals nitrogen away from plants. Blanket the perennial beds with a two-inch covering, but keep the mulch away from the stems of the plants. You get these bigger pieces when the lumber is cut with a plane. Sawdust should not be worked into the rose beds because it steals nitrogen from the plants. Spread a two-inch layer of sawdust and keep the mulch a few inches away from the trunk of the bush.
Pine needles make an excellent mulch because they are porous and moderately acid.
Check at area parks or ask your neighbors who have pines to share their needles. Layer a two-inch covering of pine needles out to the drip line of the tree. The mulch should be at least a half-foot away from the trunk. Next week, when you cut again, spread another one-inch layer. I spread the leaves two or three inches thick, and it's a wonderful mulch that breaks down over the winter months.