Dahlia Dynamics
I hear the same questions over and over again: “What am I doing wrong???” and “How do I get my dahlias to have a longer vase life? They are dead in only 2-3 days.”
Dahlias are easy to fall in love with, so it’s distressing if they don’t last as long as you want. You read about all kinds of solutions that may make a slight difference. Often, I think “doing something” just gives you a sense of control; that if you get it just right, you succeed.
But let’s go back to the driving factors
The Real World
First off, you need to understand the differences between the shapes of dahlias & bloom sizes because they are critical to the potential vase-life.
Tight Petaled Ball Dahlia
Large 8” Laciated Decorative Dahlia - CAL
4” informal decorative - Sweet Natalie
Most dahlias fall into one of three main groups: the decorative, the cactus, and the ball form (but there are 17 recognized groups). https://gardenerspath.com/plants/flowers/dahlia-types/
Decorative dahlias have flat, broad petals that are sometimes wavy. The Café au Lait is a decorative dahlia. They will lose moisture quickly.
Cactus dahlias have spiky blooms. The petals are rolled and pointed. They hold onto their moisture better.
Ball dahlias are obviously ball-shaped. The smallest ball dahlias are called pompons. Very tight form is longlasting.
WHY the difference in Life Span?
It boils down to transpiration, otherwise known as water loss from the bloom petals.
Tiny tight petals lose water slowly while large laciniated dahlias lose large amounts of moisture through their long, loose petals. The larger they are the quicker they dry out (die).
Harvested at the same “stage” of life you can get a pretty consistent vase life between dahlias by their shape & bloom size. Smaller, tighter petals conserve moisture while large blooms with fringed petals lose moisture.
For longer vase life you would choose smaller ball varieties; then larger ball-shaped blooms, formal, informal, and waterlily shapes.
The shortest lifespan are the big dramatic guys. With best management practices & proper harvesting, 4-5 days would be the max. I’d pick the smaller blooms of the drama queens to get the best longevity. That is why the drama queens are called “event flowers” not typically used in arrangments where you need them to last at least a week.
HARVEST when?
Ah, the gotcha question. WHEN should I harvest to get the longest useful life?
Almost gone…
pollen is developing
Look at FRONT first! (not the back), look at the center of the dahlia.
The central area where the pollen becomes visible. When that shows up, Times Up. The flower bloom’s job in life is to produce pollen and once that happens it shuts down. The bloom may look gorgeous but nature can’t be thwarted. You might get a day or two (ok for a same-day event) but after that it is toast.
Center completly blown out with pollen (Froggie is pest patrolling!)
Looking at the BACK of a bloom can tell you if it’s getting close to its demise if you see the petals curling back to the stem-bloom connection. If I’m deadheading and just beginning to see the start of pollen development, I check the back of the bloom. If it hasn’t started curling back I know I can still get useful life from the bloom for an event.
TECHNIQUES for longevity
You have heard it said for all flowers.
Harvest in the early morning, the cool of the day.
I suggest you water the plant base well the night before so they get a good drink.
Cut into cool /room temperature water, preferably with hydration solution* added, with stems stripped of leaves that would be below the water line.
Move fairly quickly to a shaded cool location, for at least 3-4 hours, so it can hydrate. It didn’t know it was going to get chopped from its water source so it needs a good long drink.
Recut stems at a 45-degree angle, and put them in water with flower food, when ready to design. (Flower food has a bit more sugar to help the bloom live longer and maintain its color).
Change the water/solution every 3rd day.
NO, I don’t burn, boil, or heat the stems for longer life. (if you do, I’d love to see the results of a comparison test, but I’ve not found it useful)
Hydration Solution has a tiny amount of bleach to kill bacteria brought into the water by the stems, Citric Acid (lemon juice) to reduce the pH of the water, down from 7 to 3-4pH and a small amount of sugar (carbohydrates).
Flower Food is the same thing except more sugar to help maintain the bloom.
Hydration Solution in a T-Bag (just drop it in the bucket)
https://thegardenersworkshop.com/product/cut-flower-holding-solution-t-bags/
Yes, Your water quality does make a difference.
If you can test with pH papers /strips (at garden nurseries) you can get a good idea of your pH but city water is usually around pH of 7. Stems take up water most effectively at a pH of 3-4. (Thus the reason for citric acid is to make the water more acidic.)
Make sure you don’t have treated water (fluoride, heavily chlorinated). Some people use distilled water, or let their water rest for 24 hours (to release chlorine). Hearing how lead pipes are leaching lead into our water I need to research if that affects the bloom vase-life!
FYI: Dahlias were imported by Europeans to Europe from Central America (2-3 varieties). The indigenous population used them in many ways; tubers as a food source, medicine, and the stems as water containers, to carry water. They were huge stems! Not our tiny guys that we see today.
From those 2-3 varieties, thousands of variations have been developed by breeders. 57,000 registered named dahlias so far.
SPECIFICS: Technically there are over 42 specific cultivars (and thousands of variations). We won’t go there but if you want the details here is the the link to the American Dahlia Society (ADS). https://www.dahlia.org/guide/form.html
