Cut the hydrangeas in mid-morning before the blossoms dehydrate in the heat of the midday sun. Use shears to make a clean cut, and leave at least a 6-inch stem on each blossom.
Pull all the leaves from each stem. Leaves that sit inside water die and can cause a whole bloom to wilt or droop prematurely.
Fill a vase with lukewarm, 110-degree Fahrenheit water. The stems absorb warm water more readily, making them less prone to drooping.
Dissolve a commercial flower preservative in the vase's water. The preservative supplies nutrients for the hydrangeas and prevents bacteria from attacking the blooms and causing them to wilt.
Cut off the bottom inch of each stem at a 45-degree angle. Hold a stem underwater as you cut it so air bubbles don't enter and weaken the stem.
Adjust the water level in the vase if necessary. Make the water level sit just beneath the hydrangea blossoms. Arrange the flowers so the petals aren't submerged in the water.
Change the vase's water every two days or sooner if it becomes discolored or cloudy. Fresh water helps to keep hydrangea blossoms perky and healthy.