Once you cut a sunflower, they will wilt and die if they are not properly cared for. Whether you grow your own sunflowers, or you purchased them from a florist, you should place them in water as soon as possible to keep them alive. Sunflowers are available year round and usually will last about seven to 15 days once cut, if properly tended to.
Turn your faucet on to cold water and hold your sunflower's stems under the running water.
Trim the end of each your sunflower's stems a 1/2 inch from the end, using trimming shears or a sharp knife, while the stems remain under the cold water.
Pluck off any foliage that will be submerged into the water once your sunflowers are placed into a vase.
Place your sunflowers into a vase that is large enough to hold them.
Measure a 1/2 tsp. of sugar and combine it with a quart of cold water. Stir the mixture until the sugar dissolves. If you have floral preservatives you may skip this step and use them as a replacement for this mixture.
Pour the mixture into the vase and then fill the remainder of the vase with cold water until it is close to the top of the vase.
Repeat this process every three days.