Dahlias are the flower we get the most questions about, and the most complaints about. People buy them, put them in a vase, and two days later the heads are drooping. It is not the flowers' fault. It is almost always a handling issue, and most of it is fixable.
Cut them in the morning, not the afternoon ¶
Dahlias cut in the morning, when the stems are still full of water from the cool night, last significantly longer than those cut in the afternoon heat. If you are cutting from your own garden, do it before 9am and put the stems straight into a bucket of cool water. If you are buying from us, we cut to order in the morning and the stems go straight into our cold store at 2 degrees Celsius before delivery.
The boiling water trick is real ¶
Dahlia stems have a milky sap that can block the water uptake channel. The fix is to dip the bottom two centimetres of each stem in boiling water for about 20 seconds before putting them in a vase. It sounds alarming but it works. The heat seals the sap and opens the channel. We do this in the studio for every dahlia stem we process.
Change the water every day ¶
This is the one people skip. Dahlias are heavy drinkers and the water goes cloudy fast. Change it every day, recut the stems at an angle each time, and keep the vase out of direct sunlight and away from fruit bowls. Ethylene gas from ripening fruit shortens the life of cut flowers noticeably.
Cold nights help ¶
If you have a cool room or a conservatory that drops below 15 degrees at night, move the arrangement there overnight. The cold slows the metabolism of the flower and adds a day or two to the vase life. This is essentially what our cold store does, just at a more extreme temperature.
When to give up ¶
A dahlia head that has gone soft at the base of the petals is done. Pull it out of the arrangement rather than leaving it, because decaying flowers release ethylene and speed up the decline of everything around them. The remaining stems will last longer without it.
With the right handling, dahlias from a good grower should last five to seven days in a home vase. If yours are consistently failing before that, the issue is almost always the water temperature or the stem cut. Come and talk to us at the studio if you want to go deeper.