Question
Hi there,  I bought two small lilac buxhes two1/2 years ago and niether have flowered at all.  Any suggestions?  

Answer
The lilac may not be blooming because it is getting too much shade or nitrogen-rich fertilizer. You might be able to stimulate it to set flower buds by driving a straightedge spade into the ground around the edge of the spread of the foliage. Do that in about six places. This mildly shocks the plant into a reproductive cycle.

There are several reasons lilacs don't bloom. The most common problem is a lack of sunlight. In order to bloom, lilac bushes need at least 6 hours of sun per day. If your lawn (or your neighbor's lawn near your lilacs) is frequently fertilized, your lilacs may also be getting too much nitrogen. Nitrogen promotes lush foliage, while inhibiting flowering. When planted in decent soil, lilacs usually do just fine without fertilizing. If they need it, use a fertilizer with a high ratio of nitrogen (second number) and apply it in the early spring. Organic sources include bone meal and fish emulsion. Incorrect pruning is another common problem. Pruning should be done no later than mid summer (July) or you risk cutting off next years flowers. You may have also planted your lilacs too deeply. If you think this might be the case, pull back some of the soil so the tops of the roots are slightly exposed. Also, you don't mention what type of lilacs you're growing. Common lilacs need cold winters in order to set their flower buds, but these same cold winters can kill the buds of less hardy varieties. Finally, lilacs prefer slightly alkaline soil (pH 6 to 7). Having your soil tested is the only way to know whether or not it's too acidic.