Couldn't you just stick those cups into colored cups? or perhaps just cut them and drop them in other cups? Or do like stinky said, wrap some foil around all them.

Don't forget the new drainage holes either way!
Dyranty Reviewed by Dyranty on . Leaves continuing to yellow... Grr! I transplanted my plants from 5oz to some 24oz clear cups where they should be good for a while. They are also now in FF Ocean Forest with a good amount of perlite! They have not been fed in some time, and were watered last week (and then I transplanted). They otherwise look healthy, but now they are starting to look like tie dye! Could it be a Nitrogen deficiency? Or even worse, Nitrogen toxicity? Soil: FF Ocean Forest PH: 6.5 Nutes: FF Grow Big (but not recently) Rating: 5