Planting and Growing Lilac Bushes

Just continue to remove any dead wood and prune out the oldest canes each year. If this doesn't work, you could try more serious pruning as discussed on this page. In terms of suckers, here is more detail:  If your lilac grew on its own roots, it is not "required" to remove the suckers but know that they wll grow into new branches which will flower in a few years. It depends on what you envision for your property. It's only the grafted lilac that requires removal of suckers. If you leave the suckers from below the grafting, the suckers will overtake the graft.

Young lilacs generally take time to bloom. Most flower after 3 or 4 years though some take longer. Some tips: Prune at the right time as lilacs bud off old wood and you may be removing the flowers. Prune 2 or 3 weeks after the time when they would have flowered. It's good that you have sun. Give them slightly alkaline soil (pH 6-7) as too much acid can affect blooming.  Don't give lilacs too much nitrogen fertilizer which encourages lush leaves at the expense of blooms. Hope this helps!

Hi, Alex, Every year we receive letters from people who are disappointed that their lilacs bloomed sparely. Sometimes older lilacs need a big prune, but if you prune lilacs back extensively, it may also take a number of years before they bloom again. They should produce flowers in time, but it could take one to three years, sometimes longer. See pruning section above.
Fertilizer is rarely the answer to a plant that isn't blooming. Lilacs are not heavy feeders; if your soil is fertile, that is usually fine. Amending with manure or organic matter is helpful; the only "rule" with lilacs is to avoid fertilizer with excess nitrogen which causes leaf growth at the expense of bloom.
Moisture isn't usually related to lack of blooms; it's associated with plants' roots and how well they thrive. Lilacs do best in well-drained soil.
You did not do anything wrong. It's OK to prune extensively. For older plants that need complete renovation, we often prune with a foot of the ground. However, it must be recognized that severe pruning results in the loss of blooms the following year(s).

Hi Lori, We do get lots of questions from southern readers who would like to grow lilacs (just as northerns would like to grow tropical flowers!). Lilacs simply don't thrive in warm climates. It's not just the Sun; lilacs need a long period of winter chill in order to bloom well. A good substitute for lilacs in the South is lilac chaste tree (Vitex agnus-castus).  If you find a lilac that blooms well in your region, we'd love to know! There are always new experiments. 

Hi Sarah, There are many reasons why the lilac may not have established well. For example:
Did you plant in the spring before the buds starting to unfold?
Did you plant too deep? You wan to set lilacs 2 or 3 inches deeper than it grew in the nursery.
Did you get a soil test? (Lilacs aren't picky but they don't like acidic soil).
Is the soil fertile? Did you add in compost?
Does the soil drain well? Lilacs hate "wet feet" and you don't want the roots to rot. 
Did you water it in -- and keep the soil moist (not wet) for the first 3 to 4 weeks? 
Do you have mulch around the lilac--if so remove! 
Lilacs do naturally send out roots to survive.
You may wish to get a sample to your cooperative extension because there are many reasons why the lilac may not be doing well. Normally, they transplant well (assuming it was healthy when you planted it!).