Carnation bouquets can live for several weeks even after being cut. Like any other flower, carnations will last even longer with proper care. To keep cut carnations looking beautiful for up to three weeks, provide them with a healthy environment and keep flowers out of direct sunlight and away from heat sources or cold drafts, recommends the Society of American Florists.

Water

Flowers continue to need water even after they are cut. Room temperature water is easier for flowers to absorb. Cut carnations can continue to look fresh for two to three weeks in distilled water, which has a low mineral content. Avoid using either hard or softened water, since both contain dissolved minerals, which can be harmful for cut flowers. Fill the flower vase with clean distilled water at least every other day.

Cutting Stems

Place carnation stems under water and cut at a 45-degree angle, taking off an inch or two from the bottom of the stems. If you don’t re-cut the stems before placing the carnations in water, the flowers will wilt after just a few days. To keep carnations looking fresh longer, submerge cut stems in at least 3 to 4 inches of water. You may find it easier to cut the stems under running tap water before placing the flowers in a water-filled vase. Cutting the stems while they are under water prevents air from getting into the stems. Remove any leaves from the part of the stems below the waterline; this can help prevent bacteria from breeding. Re-cut the stems each time you change the water.

Eliminating Bacteria

Clean the flower vase thoroughly to protect against the growth of bacteria. Wash the vase in hot soapy water and rinse. Add 1/4 tsp. household bleach per quart of water. The bleach destroys bacteria, helping to keep the water clear. If you don’t add an antibacterial agent to the water, bacteria and fungi feed on the sap that leaks from cut flower stems. As bacteria multiply, they clog the openings of the tubes in the stem. This prevents water from getting to the flower. You can also place an aspirin tablet and a copper penny in the bottom of the vase. The aspirin works as an acidifier, while the penny acts as a fungicide to keep the water from getting cloudy. Make sure the penny is made of copper and not simply copper-coated.

pH Level

To help maintain the pH level of the water, add 2 tbsp. lemon juice or vinegar as an acidifier. Either white or apple cider vinegar will do. Acid helps water move up the flower’s cut stem more easily so that the leaves won’t wilt. If you use bleach as a bactericide, don’t use vinegar as an acidifier. Mixing the two can produce toxic vapors. In fact, avoid mixing any ingredients together before adding to the water. Instead, add each ingredient to the water separately.

Nutrients

Feed cut carnations by adding table sugar or lemon-lime soda to the water. Use 1 tbsp. sugar or mix 1 part lemon-lime soda with 3 parts water. Do not use diet sodas since these do not contain sugar — the main nutrient your flower bouquets need to stay healthy. Sugar is similar to the natural nutrients flowers get from the soil and will help your carnations last longer.