I purchased 3 varieties of Lilacs about 2 1/2 years ago from Lowe's. They were in 2 gallon containers, but appeared to be fairly established and healthy. I understand that lilacs can take 3-4 years before really taking off, but I'm concerned about the plants. All planting conditions/light conditions are good, but they have not gotten any taller since planting (only about 1 1/2 ft) and no buds appeared this spring. Is there hope for them?? Should I be pruning them even though there are only 1 or 2 branches on each plant?