I have about a dozen bulbs I keep in pots. They all started out a deep red color, and when they rebloom they are very orangey. They spend the summer on a patio under shadecloth and get regular water and fertilizer. I bring them in late summer and they bloom from January through summer. What am I doing wrong? I would really like to get that deep red color back.
In "Hippeastrums the gardener's amaryllis" by Veronica M Read on page 173, Mz. Reed equates more sunlight with deeper hues. I have seen this happen in my own garden. I have attached a photo of 2 scapes from 2 different Blossom Peacock bulbs. One was shaded. The other received full morning till early afternoon sun.
So - your shadecloth may (or may not) be a problem.
You could test this by letting a few bulbs summer in full sun and then compare their flowers to the ones that spent the summer protected by the shadecloth. If you are able and choose to do this, I would love to hear about the results.