Your Valentine's Day bouquet will last a little longer if you use a preservative. To survive, flowers need three ingredients: carbohydrates, biocides, and acidifiers. Carbohydrates are necessary for cell metabolism; biocides combat bacteria and maintain plant health; acidifiers adjust the pH of water to facilitate and increase water uptake. Home mixes can be as effective as commercial preservatives. Try this easy-to-make recipe.

1 teaspoon sugar
1 teaspoon household bleach
2 teaspoons lemon or lime juice
1 quart lukewarm water

Read more about caring for your cut flowers in our guide to cut-flower care.