Flower Cents

Scene showing materials from Flower Cents activity

Can adding a penny to a vase of flowers help them stay fresh longer? Find out by trying this at-home experiment!

Grades: 3rd and up

Materials: Flowers (freshly picked or purchased); 2 glass cups, jars, or vases; water; 1 penny from before 1981; toothpaste; Flower Cents Activity Worksheet (PDF); 1 penny from after 1982 (optional)

Time: Set up 10-15 minutes; experiment runs over 7 days


Did you know that copper naturally kills bacteria? Since pennies are made from copper, we think putting a penny in your flower’s water might keep them fresh. Luckily, it is pretty easy for us to test out this theory!

  1. Check the date on your penny. Make sure it is from the year 1981 or older. Pennies from before 1981 have more copper content.
  2. Prepare your coin. Use a small bit of toothpaste to clean your coin. Rub the toothpaste on the coin and let it sit for 3 minutes before rinsing.
  3. Trim your flowers. With an adult’s help, cut the flowers to fit the 2 cups, jars, or vases.
  4. Fill the 2 containers with about an inch of water. Make sure the same amount of water is present in each container.
  5. Place flowers in each container. Remember, we need to have two different containers holding flowers to perform our experiment. Pick one container to be the “control.” The control is the container that won’t have a penny so we can see what happens to the flowers if we don’t try to make them last longer. The other container will be the “variable.” The variable container will have a penny in it! Drop your clean penny into the variable container. Keep both containers in the same place, like a window ledge, table, or counter.
  6. To track the results of your experiment, use the Flower Cents Activity Worksheet (PDF) to write down your observations. You can even take a picture of the flowers so you can remember what they looked like along the way.
  7. After 7 days, write down your conclusions. What happened? Did the penny make the flowers stay fresher than those in the control container?

For additional fun, try the same experiment using 2 different pennies – one penny from 1981 or before, and one from after 1982. The older pennies are made with more copper. Which penny will keep flowers fresher? Find out for yourself!