Eastolivia demonstrates this hack in her TikTok video. Start by cleaning the stems of your dahlias, especially below the water-line. Next, take a clean pair of shears and cuts the stems at a 45 degree angle below the water-line. Grab a clean vase and line it with paper towels to protect the petals from steam. You’re going to add a couple of inches of boiling water to your paper-lined vase. The hot water is thought to disrupt bacteria and extend the life of your dahlias. Finally, just wait for this water to cool to room temperature, and once it has cooled, take a new vase, add fresh water and a little flower food, and then add in your beautiful dahlias.

Gaumond suggests that hot water may be effective in killing bacteria or unclog the stems of a fresh cut flower, allowing them to absorb water more effectively. However, he doesn’t recommend using boiling water because of the risk of shock to the flower that could lead to a rapid loss of petals and wilting. Instead, he advises that warm water is better than cold. We recommend cutting garden flowers in the morning or early evening when the stalks are filled with water, and use warm water between 80° and 110°F. This is because there is more oxygen present in cold water that can cause air bubbles to form in the stems of your flowers, and this will block their water absorption.

Source: housedigest.com