The best time to prune lilac is late spring -- immediately after they finish blooming. If you prune them later in the growing season or during winter, you'll remove flower buds and decrease the amount of spring bloom.
Lowes sells the 4 to 6 round PVC pipe with holes already drilled. Purchase an end cap, fill with rock, soil, and plant. You can put these in the center of a very large pot to stabilize, and add amazing height and color to a container that has trailing plants (no end cap or rock needed if you are placing in a container) LOVE THIS!! MOAR FLOWERS! crafts-and-diy