I have been growing amaranthus from seeds the last two years . I have Joseph's Coat, Love Lies Bleeding and Illumination. I really like Joseph's Coat but don't understand why it changes from a beautiful three color plant ( green-yellow-red ) to just a bright red after the plant has been growing for a short time. I do not fertilize Joseph's Coat to keep bright colors. If there is something I can do, please let me know. It seems like after a while the Joseph's Coat and Illumination look the same!
My plants are grown in full sun, however, this year the heat seems to be brutal on the plants. I put some in partial sun and they seem to do better.
I have been learning how to grow the amaranthus the last two years because next year I plan to dedicate a large portion of my yard to amaranthus. Any advice or help you could offer will be appreciated.
Thank you, Terry K.
I don't think this has anything to do with your care, although sun/shade can make a difference. This is just typical for the types of amaranthuses you are growing. The colors that develop are primarily based on the genetics of the embryos in the seeds.
As you have experienced, amaranthus color develops over time, often changing from the early color form to the later color form. The colors change as the plants grow taller. This is not necessarily a problem, the colors are amazing.
Providing more shade does mute the colors. If plants in part shade produce a color form more to your liking, you might focus growing that variety in some shade.
Consumer Horticulture Specialist
The LSU AgCenter and the LSU College of Agriculture