MadSci Network: Botany

Re: If I water plants with colored water will it change the color of the plant?

Date: Wed Apr 3 01:38:23 2002
Posted By: David Hershey, Faculty, Botany, NA
Area of science: Botany
ID: 1017758565.Bt

Cut flowers are often dyed by placing the stems in a dye solution. However, 
flowers and leaves of intact plants probably cannot be dyed by watering them 
with a dye solution because the dye solution is not absorbed by the intact 
roots. Roots are very selective in what they absorb and generally only absorb 
water and mineral nutrients. Cut flowers have the roots removed so the dye can 
easily enter the cuts in the water-conducting tubes (called xylem). If you want 
to do an experiment with dyes and plants, you might compare a soil-grown plant 
with a cut flower. 

If you grew a plant in hydroponics and carefully cut the tips off many of the 
roots, then maybe you could get dye to enter. However, unless the plant was in 
flower or the leaves of the plant are mainly white, like in a variegated spider 
plant, it might be difficult to see a color change in the leaf even if the dye 

I once potted chrysanthemum cuttings in potting soil and watered them with a 
fertilizer solution containing a red iron chelate. I noticed a little red 
coloring in the leaf tips because some of the roots had been damaged and the 
chelate could enter the xylem.

One plant whose flower color can be changed by the chemical composition of the 
soil is the florist hydrangea. Making the soil pH acid by adding aluminum 
sulfate or sulfur causes blue flowers. Keeping the soil pH high makes the 
flowers pink. The aluminum absorbed by the flower causes the pigment in the 
flower to change to blue. Aluminum is unavailable to the plant at a high pH. 

One way to make plants change color is to grow them in hydroponics and deprive 
them of one or more mineral nutrients. For example, iron deficient plants often 
turn from green to yellow or white because of iron deficiency.


Re: Can all white flowers be turned color with food coloring the water?


Re: Capillary action in flowers with hot water?

Hydrangea and soil pH

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