Lilacs

Many lilac flower clusters on the plant with the sky behind
Common lilac, Syringa vulgaris

Lilacs are extremely popular and one of the most fragrant flowers to bloom in spring. And since they grow as big sturdy shrubs they’re a highly useful landscape essential. They make nice specimen plants (for spring) and beautiful fragrant hedge plants.

The flowers, which are one of my top five fragrant flowers, make excellent cut flowers for a bouquet. They’re not very long-lasting but if you harvest, condition, and maintain them correctly you’ll get the best vase life possible, which is at least 5 days. Worth it for having that fragrance in your home!

Another benefit to the landscape is that they are almost completely deer resistant! At most you may get a few nibbles depending on their dietary needs at the time.

There are several species of lilac and many, many varieties available. The original common lilac species, Syringa vulgaris, comes from Eastern Europe.  Other species, S. oblata and S. protolaciniata come from China.

There are even reblooming varieties that blooms a second time on the new growth produced through  the summer. One’s called Bloomerang lilac, it’s a shorter variety to 4-6 ft. tall and wide.

What Lilac Flowers are Like

Lilacs bloom sometime in mid-spring, depending on where you live and the variety you have.

The flowers form pyramidal or conical clusters. Each individual flower is a short tube with 4 petal-like lobes that flare outward. Some hybrids have double flowers giving each little flower 8 or even more petals for a very full appearance.

The flowers attract and feed hummingbirds, butterflies, and other pollinators.

All the different varieties of lilac offer flowers in different colors and shades from traditional lilac to white, ivory, and a whole range of purples and pinks. Some even have markings like striped edges.

Each variety has a different fragrance. So if the fragrance is what you’re most after, you need to purchase your lilacs when they’re in bloom or after you have sampled a variety of flowers to get what you most like.

My tip? I think the best is the common lilac. While different varieties can smell differently they also have different fragrance intensity. I feel the common lilac is both intense and a perfect fragrance, capturing high and low notes with a bit of a tangy citrus. It’s also what I grew up with, that may sway me.

Dark purple lilac flowers with white edging on the petals
'Sensation' lilac, one of many varieties that offer different fragrances and flower features.

What the Plants are Like

Lilacs are deciduous. To use them as a screen, the best performance will be in the late spring -fall season.

The common lilac, Syringa vulgaris, grows up to 20 ft. tall, if allowed. It can be maintained at a lower height, to around 12-15 ft. tall or less. Other varieties offer various sizes to help them fit into smaller spaces or to work as smaller shrubs and hedges, such as ‘Miss Kim’ which grows to 8-9 ft. and ‘Dwarf Korean Lilac’ which grows to 4-5 ft. tall.

Lilacs spread by suckers. When you plant one it will spread wider each year, so be prepared for that. You can dig the suckers out and replant them if you like.

Lilacs are fairly long-lived, lasting 25 – 50 years or more if well cared for.

How to Grow Lilacs

Zones: 3-7, with some varieties bred to perform well in zone 2 and some to flower well in zone 9; full sun.

Lilacs need enough winter chill to bloom well, just like fruit trees need a certain amount of winter chill to bloom. So a Los Angeles area botanic garden, Descanso Gardens, bred some varieties to bloom in their warm climate. They’re called the Descanso Lilacs.

Lilacs are quite easy to grow. They need soil with good drainage. Use an organic flower fertilizer on the surface of the soil and mulch with a good compost and wood chips to increase soil fertility and conserve moisture.

Water deeply but infrequently. The roots like to dry out between waterings.

Do not keep soil too wet. Do not plant where there will be a lawn underneath, it will be too much water.

Lilacs can be troubled with powdery mildew. It’s not too serious because the bloom is over when they’re susceptible. But it is unsightly. They need good sun and good air circulation to help keep it at bay. Six hour of sun is necessary.

Pruning: Best bloom is achieved with proper pruning.  And the best time to prune is after they bloom.

Lilacs bloom on second year wood. That means flower buds grow on new wood this year and bloom next year. So after your lilac has finished blooming, prune the flowering branch to a pair of leaves. This removes the spent blooms and allows two branches to grow and develop flower buds during the summer, where there was one.

This pruning produces more flowers and keeps the overall height of the plant to where you want it. It you don’t prune back your flowers will be higher and higher on the shrub…to where you won’t smell them anymore 🙁 . If you need or want to prune back hard, you’ll have fewer blooms for a couple of years.

For the repeat bloomers, prune late in the dormant season. Cut the previous year’s growth to various lengths. And once the plant is established, make a yearly habit of cutting out a few of the oldest stems. 

Common lilac flower cluster
Common lilac (Syringa vulgaris) flower cluster.

How to Harvest Lilacs

Cut your lilac flowers well before they’re fully open. Cut them in the early morning or in the evening coolness.

Since lilacs are woody and the flowers are on woody stems the flowers you’ll use a different method of harvesting your lilac flowers. You want to maximize the ability of water to travel up into the woody stem.

Choose a spot to cut at a node of leaves on the branch. Cut the stem at an angle. This makes a longer exposed area of the water carrying vessels to absorb water. Next, take your nice sharp clippers and carefully make a slit in the middle of the cut end and cut up about an inch or two. This will expose more of the water carrying vessels to absorb water.

Plunge the stem immediately into water, preferably warm. Let the flowers condition in a cool dark place for several hours before arranging.

If you see any hint of wilting, retrim the stem in the same way. Your lilac bouquet should last 3-5 days or more with your careful harvesting method.

My Favorite Varieties

While I think there are many nice, fragrant lilacs, my favorite remains the common one, Syringa vulgaris. I love the simplicity of the flowers, no extra frills, and to me it still beats all the other fragrances.

Sources of Lilacs

Go to your local nursery to test what different varieties smell like. The common lilac may be hard to find. Here are a few online sources:

NatureHills.com   

Arbor Day Foundation

PlantingTree.com

BrighterBlooms.com

The top three offer bare-root plants, which are perfect for fall or winter planting, as well as potted plants to plant anytime.

Flowers to Go with Lilacs

Sun-loving perennials for the foreground that don’t want too much water:

Yarrow

Echinacea

Perennial sunflower