Let’s start by learning a bit about what determines when flowers can and cannot blossom. Plants flower when there is a change in their environment that makes it necessary for the plant to produce seeds within a particular time frame.
Lilacs can bloom in the fall, but they rarely do so. Flowers usually bloom when they sense the days getting longer, but the days shorten during the fall, so lilacs close during this time of the year. However, prolonged exposure to artificial light can counter this behavior.
The change that triggers flowering is usually longer days. For example, as the spring season arrives and days get longer, plants know that they have a limited window of time before the growing season ends to reproduce themselves. We call this signal photoperiod sensitive because plants react differently depending on how much light they receive each day (how many hours of daylight there are). In temperate climates, seasons are very distinct because of significant changes in the number of hours of light, the amount of rainfall, and the average temperature. These environmental differences affect plants’ flowering times by triggering photoperiod-sensitive mechanisms that initiate flowering.
Changing seasons also represent a change in plants. Plants usually grow rooted (immobile) in one spot throughout their lifetime, but sometimes they need to move or respond to an external stimulus such as a predator attack. This is when growth regulators can play a role in their development: these chemical messengers help a plant adapt by changing its appearance. When leaves start turning yellow for fall, growth regulators are usually involved because they play essential roles in this process known as abscission. In other words, these chemicals trigger leaf drop from trees.
Let’s come back to the lilac flower. You may think that flowers bloom in spring or summer, but not fall. Can you guess why? We told you there were lots of external factors involved in plants flowering! Depending on which part of North America you live in, environmental conditions can vary drastically during different seasons, sometimes influencing plants differently than expected. For example, lilacs are one type of plant that blossoms earlier than expected in some North America because the weather is warmer and drier in the summer months.
Suppose these environmental changes cause a more extended photoperiod. In that case, two critical things happen: (1) plant growth is reduced due to the lack of rainfall and higher temperatures, and (2) specific growth regulators accumulate to play their role in abscising leaves. This results in flowers blooming earlier than expected.
How late can lilacs bloom? An Illustrative Narrative
Thandiwe takes a deep breath of the lilac-scented spring air and settles back onto her towel. The light is fading but, if she closes her eyes, she’s almost able to convince herself that her radio is playing some forgotten song by James Brown or Billie Holiday instead of the accursed birdsong recording it currently has on loop. She allows herself a small smile as she thinks about how much cheaper it would be to buy music for this month but then remembers that anything more than basic food rations would have to come out of their monthly cycling stipend – money that, by now, is usually already earmarked for the following month’s rent. And besides, anything that costs money has to come out of the housekeeping budget – and even if she was allowed to keep personal cash (which she isn’t), it’s not like this month would be a good time to splurge anyway.
It looks like rain later tonight; Sthandiwe can smell the hint of moisture in the air over the more pedestrian scents of mud and cow dung from the farm across from their campsite. She’d spent half an hour earlier on her hands and knees after coming back from her run through town, using a stick to help scratch another tally mark into what had been an ample enough space between two flat rocks to use as a tally mark, but is now more of a dangerously slanted line.
The rain was the only good thing she had been able to think about on her run through town. She hadn’t been running at full pelt; it’s not that kind of jog – the kind where you push your limits until your lungs burn and you can barely feel your feet crunching into the earth. It was, she thinks as she rubs at her sore calves, more like the kind of jog where you’re running just fast enough to keep ahead of your thoughts, which is why it had taken almost half an hour to make it back from town; jogging and picking up the other essentials on the way home – toilet paper (it was out again), stamps (the post office had also run out) and food (which included another jar of peanut butter and a bottle of red wine). Maybe tonight, she would feel inspired enough by those ingredients to cook something that resembled a meal.
What time of year do lilacs flower?
Lilacs are flowers that grow on trees. They can be found in the spring, summer, and fall seasons. The only thing that changes is what type of tree they are growing on. For example, if you find lilac flowers in the summer season, they may be growing on a dogwood tree instead of an apple tree or another kind of tree. Lilacs flower in these seasons because there is more sunlight during those times, allowing them to blossom.
Can lilacs bloom all year?
The short answer is no, and they can’t. But the way they grow leaves little to be desired for some people who like their outside landscaping to look like a rainbow. In spring, you see only the purple and pink colors in the flowers as those are the first blooms to appear on a stem. It’s not until later in the summer that the white flowers start blooming, but many people are getting sick of seeing purple everywhere by then.
This phenological change has to do with how different plants bloom and grow at various times throughout the year. During spring, lilacs grow new leaves and stems, along with their flowers for that growing season. Every plant has a specific time frame when they flower because it takes energy to put on new growth. By summer, most plants have reached maturity, so there’s no need to spend more energy making new growth parts or putting out flowers. The older leaves die off after producing seeds that will later be distributed elsewhere by wind or animals. It’s during this second phase where the flowers change from purple to pink and white.
What do you do with lilacs in the fall?
It’s not crazy to think you might want to be rid of those pretty lilacs come fall, but before you rake them up and toss them in the dumpster, consider these six ideas.
Six things to do with lilacs in the fall – After flowering, cut back a shrub-type species once all blooms have dropped off. This removes dead flower parts and encourages fresh growth for next year.
Trim back the foliage after bloom – Either clip or pull – use gloves! – if your bushes are looking messy, again encouraging healthy new growth for blooming next spring. If you have a trouble-maker among your lilac plants, remove it from the rest of the group, so they don’t cross-pollinate and form seed.
Invigorate lilacs with a fruit tree fertilizer – Rake and remove all dropped blooms and foliage, then fertilize (at least four weeks before the first of September) to get bushes off to a good start next year. You can also use manure or compost for this purpose if you prefer not to buy anything.
Decorate with bags of blossoms – If you like, gather up your lilac clippings and stuff them into paper (not plastic) yard waste bags for an earth-friendly fall decorating idea. Add some color by mixing in maple or poplar leaves; tie or staple the top closed before leaving them on the curb on collection day.
Make cut flowers – Cut lilacs when they are almost ready to open, leaving about 4 inches of stem. Strip off leaves that will fall below the water line in a vase or bucket, then fill with lukewarm water and enjoy.
Lilac spritzer – Make your lilac perfume by filling a spray bottle with no more than one part vodka to nine parts water, then gently shake so the alcohol mixes evenly with the water. Spray lightly on clothing or linens for an intoxicating scent.
Lilacs are spring-flowering shrubs that can be found in many different varieties and colors. These perennial plants increase in the late winter, reaching an average height of 4-5 feet with a spread of 3-4 feet in 2 years when planted from the young bare rootstock. The best time to plant lilacs is when they are dormant, which runs through April for most areas of North America.
Conclusion
Unfortunately, if they were forced to bloom during the fall, it would completely ruin their blooming cycle for next year; instead, all their energy will go toward forming new growth points for next year’s before their dormancy period sets in. You will get to enjoy your lilac for many years to come. Give them the proper planting and care that they need to thrive.
