I want to make an experiment regarding seed germination on some flowering plants, probably Portulaca grandiflora, but not necessary this exact species. Some plants need light to germinate their seeds and I want to determine just how much is needed.
My idea is to use a few batches of seeds, each batch under light of different intensity. The problem is that I don't know what materials should I use to filter/block light. I was thinking of glass plates/dishes/bowls with different degree of transparency, but I don't know if the colour of the glass will influence the wavelenght that reaches the seeds. I could also try some textile cages, but this will require a lot of work I guess.
For this purpose I need some suggestions for materials to use instead of glass. Where should I ask this question, here on G&L, or on Biology, Physics, Lifehacks, Arts&Crafts? Or some other places?