Are you fertilizing these plants? Too much nitrogen will favor leaf formation over flowers. Do not fertilize. They do like soil with a pH of 6.0 to 7.5, though. Do a soil test—even a simple one—and see if the pH is within the range.

As you suggest, this is not usually a problem. So the solution provided by the Cornell U coop extension may seem like an odd answer but here goes: prune it. (Have you ever prune it?) Specifically, the coop ext says, You can prune overgrown lilacs (if relatively healthy) down to the base of the plant in late winter/early spring. This action will force new vigorous growth and put you back on the road to having a beautiful, properly proportioned shrub. Blooms may be sacrificed for two to three years while the shrub is reestablishing itself. Once rejuvenated, maintenance pruning should be performed on an annual basis.

This sounds severe, but promising, if you can wait for the regrowth. You might also consult the nursery you purchased it from (or any nursery) to see what they recommend.

There are some general standards re distance; lilacs that 8 to 10 feet from water and sewer lines should be fine.

Lilac roots will probably not break intact pipes, but they could be drawn to pipes that leak.

For more information you could contact your town inspector or a nursery person.

Morning glory roots shouldn’t be an issue for lilacs, since the lilac roots will reach much deeper than the morning glories. Plus, morning glories are annuals, meaning they die back at the end of the growing season and will no longer be a competitor to the lilac.

The best time to prune is after the bloom passes. See above also (repeated here for expediency):

• If your lilac is old and in really bad shape, remove one-third of the oldest canes (down to the ground) in year one, half of the remaining old wood in year two, and the rest of the old wood in year three. Another option for old lilacs is to chop the whole thing back to about 6 or 8 inches high. It sounds drastic, but lilacs are very hardy. The downside to this option is that it takes a few years to grow back. The upside is less work and more reward, as the lilac will grow back bursting with blooms. 
• It must be recognized that severe pruning results in the loss of blooms for one to three years. For these reasons, a wise pruning program aims to avoid severe and drastic cuts by giving the bushes annual attention.

If you are referring to the flowers, yes, you can do that.

Most of our helpful input is above on this page. Consider the suggestions for compost in spring and well-rotted manure after bloom and other care tips. Great grandmother would be happy with your success.

Hi Denise,

Red-tinged leaves can be a sign of a nutrient deficiency. The exact nutrient that the plant is lacking is hard to identify, so a good cure-all is to amend the soil with aged compost. We hope this helps!

Lilacs need chilling hours during the winter so they’re not meant for most Southern climates, whether in the ground or a container. It’s not to say it can’t be done but most lilacs require over two thousand hours of temperatures below 45 degrees F. in order to bloom. They need the cold to set the buds for next year’s bloom. We’d suggest asking your local nurseries about varieties that have low-chilling requirements. From what we read, some lilacs that don’t need as much chilling are: ‘Lavender Lady’, ‘Blue Boy’, ‘Dark Knight’, ‘Miss Kim’, ‘Betsy Ross’ or ‘White Angel’ (‘Angel White’) lilac. Lilacs need a neutral soil so you’ll probably need to add lime.

Planting a lilac shrub in a container is doable but not recommended. Lilacs grow best when their roots are free to spread out. As you said, lilacs can’t tolerate acidic soil, and the same goes for soil in pots. Most commercial potting soils contain at least some pH lowering peat moss. So you’ll need to add 1 cup of dolomite lime to every 2 cubic feet of potting soil. Also, note that lilacs can’t overwinter inside. They need those chilling hours and must go outside.

Better yet, look for a similar plant that thrives naturally in Georgia such as Syringa laciniata (cut leaf lilac).

Generally, it’s not recommended to start lilacs from seed—it may be 3–4 years until they start flowering, assuming they are growing in optimal conditions. As for your small plants, they may produce blooms in another 2–3 years, or sooner if you’re lucky and they’re happy. 

There are a few lilac shrubs that are deep purple, though we wouldn’t say they’re close to black.  Search online for: Syringa x hyacinthiflora ‘Dark Night,’ Syringa vulgaris ‘Arch McKean,’ and Syringa vulgaris “Yankee Doodle”

If you’re looking for a similar bush with deep purple, almost black flowers, search online for Buddleja davidii ‘Black Knight.’ It’s a butterfly bush but fits your description.

Hi Emily,

Cutting lilac flowers now will not affect next year’s blooms. Those buds will form in the summer.