Feb. 11, 2011

Science Dad on Flowers for Valentine’s Day

by Vince Harriman

Click to enlarge images

White Carnations fresh from the flower shop

Science Dad had two requests this week that could not be ignored: first, Beckett wanted to do a more hands-on science project; second, Science Mom wondered when she would make an appearance in this blog. With Valentine's Day right around the corner, I decided to combine both! Beckett and I have long talked about how plants and trees take water out of the ground and move it through their stems and trunks to their leaves and flowers -- first in our leaf experiment and then in our water cycle project. This experiment combines the concepts learned in both those lessons in a visually stunning way. As an added bonus, the results of the experiment will make a great Valentine’s Day gift for Science Mom.

Day one of the experiment

We began by getting some plain white carnations from our independent, locally owned florist. I called ahead and asked them to reserve some carnations straight off the truck that had not yet been re-hydrated. While this step is not necessary, it certainly speeds up the transformation. We brought the flowers home and gathered all the materials we needed -- some glasses to hold the dyed water, some food coloring, and some scissors. We trimmed the flowers' stems to a reasonable length, cut them at an angle to increase their surface area, and divided them between three glasses. We then added food coloring to each glass: red, blue, and yellow. We took our final flower and split the stem straight up the middle and placed half of the stem in the blue dye and half of the stem in the red dye. We weren't sure if this would produce a purple flower or a red/blue flower. We carefully arranged the flowers so that they would stay upright and undisturbed, then had a talk about what was going to happen.

In plants, water moves from the root system to the leaves, flowers, and branches by a process called osmosis. This is where water flows from a place of high pressure to a place of low pressure. In this case, as the plant (and especially flowers) breathe out water through transpiration, the water pressure drops at the top of the plant and water flows up. In our case, the water brings with it dye from the food coloring which collects in the flower, slowly changing its color.

Final Bouquet, presented to Science Mom!

We began to see a hint of color after a few hours, and after a day we could definitely identify flowers by the color we had added to the water. By day three we had a spectacular bouquet just in time to present to Science Mom for Valentine's Day! You can see in the final bouquet photo a yellow carnation on the bottom, a red one on the top, a blue one to the right, and a carnation that is half red and half blue to the left. Perfect for Science Mom.

(We call her Science Mom, but she really should be called "She Does Everything" Mom, because she really can do anything and everything and we are so lucky to have her! Happy Valentine's Day, Science Mom/You-can-do-everything-Mom! Enjoy your bouquet of flowers and online science project!)

Parent's Guide: Most white flowers will work for this experiment, but carnations are great because they drink a lot of water, are inexpensive, and can be found almost anywhere, including grocery stores. If you can't find flowers that haven't yet been hydrated, don't worry -- just cut the stems a bit shorter. In our case, the stems were cut to about 10 inches -- but a 6 inch stem will work faster. Also, don't be shy with the food coloring -- use plenty of drops. Ten to twenty drops per glass will speed up the color change. And finally, do the experiment in a safe place! While sun and warmth will speed up the process of transpiration (and therefore osmosis) be aware of what could happen if a glass spills! We did our experiment in Beckett's bathroom for just this reason. Don't forget to cut the stems at an angle, and if you decide to split a stem, as we did, be sure to use a sharp knife and cut as carefully as you can. Give yourself two days for full effect. If after the first day you don't see some color change, re-cut the stems and add more food coloring.


Science Dad, AKA Vince Harriman, is a freelance writer living in Annapolis. He can't do anything without the fantastic support of Science Mom! His two sons, Beckett-6 and Rowan-2 1/2 ask him ‘why’ approximately 6,549 times a day.

About Vince Harriman

Science Dad, AKA Vince Harriman, is a freelance writer living in Annapolis. His two sons, Beckett-6 and Rowan-2 1/2 ask him 'why' approximately 6,542 times a day.

The views expressed are those of the author and are not necessarily those of Science Friday.

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