There is another misconception passed down by gardeners who have 'heard it' from a real gardener so it must be true. If you plant two different colored irises close together the stronger iris color will influence the weaker iris color and they will all become the same color. In the beginning I tried to explain that perhaps a iris seed had fallen into the clumps or perhaps a much more aggressive rhizome of one iris had crowded out the lesser aggressive one. I still hear it. People who grow irises will say 'I am going to have to move the yellow ones away from the white ones or they will all be yellow in a few years. Unless I am speaking to a group I don't say anything anymore.
