It just seems to ache when dahlias—those exuberant, generous stars of late summer—stand tall but withhold their flowers. Many gardeners across the country watched sturdy stems and healthy leaves rise, only to wait in vain for buds that seem reluctant to open. This season, nature has placed unexpected constraints on dahlias, and understanding why requires looking closely at the weather’s extremes.
Heat Holding Them Back
Dahlias are not lovers of oppressive heat. When daytime highs creep toward ninety degrees and nights remain warm, the plant’s energy shifts inward. Growth slows, flower buds stall, and the plant appears to be saving itself for gentler times. Instead of bursting into bloom, dahlias conserve their strength, surviving but not indulging us with the abundance we expect.
Cold’s Quiet Delay
Cold can be just as paralyzing. Temperatures in the mid-40s, especially early or late in the season, can stunt dahlia development. Buds that might otherwise unfurl pause instead, as though waiting for a signal that the world is once again safe. The rhythm of growth is slowed, and flowering is postponed. In our region, we experienced this both in Spring and in August, just after a spell of high heat.
The Weight of Water
In some regions, flash flooding brought another challenge. Saturated soils suffocated roots, displacing oxygen and stressing the plants. Even brief inundations can cause root damage that later shows up in a lack of vigor aboveground. Excess water washes away nutrients and interrupts the delicate balance dahlias require to transition from foliage to bloom.
A Season Out of Balance
Taken together, heat waves, unexpected cold snaps, and erratic rainfall form a patchwork of stress. Dahlias, though resilient, are also sensitive. They prefer moderation. Their refusal to bloom this year in many gardens is not a mystery of genetics or carelessness but a testament to how finely tuned they are to the environment.
What to Take Away
The absence of flowers is a reminder: dahlias bloom not only because of what we do in the garden, but because of the season’s willingness to meet them halfway. Some years that balance falters. Yet even in restraint, dahlias teach patience. Their pause, however frustrating, connects us more deeply to the rhythms and unpredictabilities of nature.

We’re just starting to see the effects of changing climate indicators. More on the horizon for dahlias unfortunately.
Yes indeed. I was so disappointed. BUT now at the end of September they are all blooming. Amazing! Thank you for explaining. Our Summer was hot and very humid. And dry. But wow what a change the last couple of weeks!
Here in Asheville we had the oppressive heat and night time temps of 75…AND then it cooled down about 3 weeks ago and I am sure I heard a cheer from the dahlias as they began putting out a whole new set of buds which are giving me abundant blooms to bring everywhere I go these days!
I was assured to read this. We are in Central PA, we plant approx 350 tubers yearly. Everything you explained is exactly what we experienced! Thank you!
So glad to know that my dahlias not performing well this season- was a fault of nature not my nurture— It was a heartbreaking Dahlia season for me since many of my pricey new tubers did not make it— now do I rebuy? or just stay with the survivors of this season for next spring Despite all the money I lost the disappointment of not seeing my favorite Dahlias bloom is worse! Never thought I would even ponder giving up on Dahlias!