My 6th grader is doing a science fair project about which fertilizer is best for plant growth. We bought 2" mums to use, half were red and half were white. After several weeks the white ones started turning a light purple. What causes this?
Hmm, very odd indeed. The only cause I can think of that would cause this type of reaction would be a change in the environment. If they had been grown previously in a warm and bright greenhouse (as I'm sure they had been) then being in a cooler and much less bright place, as in the classroom, this might cause a color change.
I would make sure they have bright light, even getting some grow lights to try and copy what they had before.
Just so you know, adding fertilizer to the plants at this stage most likely won't show the same effects as if they were pre-bloom. Once the flowers form, they don't require much fertilizer.
Good luck with the science fair!
Join in and write your own page! It's easy to do. How? Simply click here to return to Ask the Horticulturist.