In a large family of undeniably stunning flowering plants, dendrobium orchids produce some showstopper blooms. One of a smaller group of orchids that are suitable for vase arrangements, dendrobiums grow long, slim and strong stems that hold multiple long-lived blooms. With proper conditioning and scrupulous care, cut dendrobium orchid stems can last up to two weeks in a vase.
Select a vase or container, and make sure that it is very clean and harboring no bacteria from previous arrangements. Fill the container with tepid tap water to the halfway point. Add cut-flower food or preservative, and stir with your hand or swirl to dissolve.
Make a fresh 45-degree angle cut on each dendrobium stem while holding the stem underwater in a full sink. Cut to the length that suits your arrangement and container. Err on the side of cutting less off the stem, as you will be making subsequent cuts in coming days to recondition the flowers and preserve the bloom.
Place the orchids in the vase to your liking. Ensure that no foliage or flowers fall below the water line, as this can introduce bacteria to the water and shorten the life of the flowers considerably. Place the arrangement in a cool spot protected from drafts and bright sunlight. Steer clear of areas near fireplaces, gas ranges and ripening fruit, as the gases emitted from these items can kill the flowers fairly rapidly.
Recut and condition the orchids every two or three days by pouring out the old water, rinsing the vase, and refilling it with fresh tepid water and flower food. Cut the stems underwater once more at a 45-degree angle, and place them back into the clean vase water immediately. When you run out of commercial floral food, simply use a teaspoon of sugar and two drops of household bleach for every gallon of fresh tepid water. This solution will feed the flowers and inhibit bacterial growth.