It’s almost my daughter’s birthday and lilacs are a part of that very sweet memory. They were in full bloom the day she was born and everyone that came to welcome her brought a big, sweet, lavender bouquet. The fragrance of lilacs never fails to make me smile.
It just wouldn’t be spring in Idaho without the wonderful fragrance and beautiful purple flowered shrubs of Syringa vulgaris, the botanical name of the common lilac. (Our state flower is not really a Syringa ( lilac), our state flower is Philadelphus lewisii,(mock orange) but that’s a story for another day).
Lilacs were grown in European gardens in the sixteenth century and are still one of the most popular shrubs that we plant in our gardens today. The fragrant flowers can be single or double and come in colors ranging from white to all shades of purple, pink and now even yellow. The flowers bloom from early to late spring, depending on the variety, but always after the leaves have formed.
The climate of the Treasure Valley is perfect for growing lilacs. They bloom best in areas with chilly winters and a slightly alkaline soil. Once established, they are fairly drought tolerant. They don’t tolerate wet feet so make sure they have good drainage. A wet environment encourages a bacterial blight which will likely kill the plant.
Most lilacs bloom on wood formed the previous year and they set buds for the following year very shortly after they finishes blooming. With that in mind, it’s important to prune lilacs (and other early spring blooming shrubs) right after they finish blooming. If you prune your lilacs after July or in early spring before they bloom, you’ll be cutting off the flower buds and you’ll loose a season’s worth of flowers.
Prune lilacs short enough to be able to enjoy the flowers. Some lilacs can grow 15- 20 feet tall with the flowers at the ends of the branches. Unless you keep them pruned to a reasonable height, the flowers will be up by your roof for the squirrels to enjoy. Cut back the stems after flowering and encourage young shoots that come up by removing some of the older stems every few years.
Older lilacs can be rejuvenated by thinning out a third of the old stems every year or so until the old branches have been replaced by young, productive stems. Lilacs can also be trained into a single stem, tree type lilac. One of the prettiest trunks I’ve ever seen is an old tree-type lilac at the Depart of Lands building on State Street. I have no idea how old it is, but the trunk is absolutely gorgeous.
Lilacs are a pretty durable shrub. They seem to thrive on neglect. Prune after flowering, don’t over water, don’t over fertilize, cut a bouquet and bring the flowers inside. Breathe in the fragrance. Ahhhh, lilac memories. I hope you find some this spring.