Rainbow roses are interesting. I saw people growing before. They are interesting but sadly I usually see colors that are unevenly distributed. Maybe there are some specific techniques that one has to take care of?
You've probably seen people growing bi-color roses. Hot Merengue, Sunset, and Double Delight are some striking examples of bi-color roses that we could all grow.
But there are some colors that you simply can't grow because the rose lacks the ability. Blue roses and rainbow roses are examples of this. You can grow lilac and lavender roses, but not true blue because the rose doesn't have the gene necessary to do it. Solid blue roses are actually easy to make though. Start with one of the white varieties, cut the stem and put into water with blue dye. It will readily take up the color. Rainbow roses are a different animal though. It requires the maker to cut the stem lengthwise several times and to gently place each piece in a cup of water with dye. So if a customer wants rainbow roses with blue, green, yellow, and pink coloring, you need to slit the same stem four times and then work each portion into a cup of water with dye (well, it's usually a test tube really). The stem sees a lot of damage this way and you can expect to lose a few roses in the process. I've heard that some florists create them with sprays, but in my opinion, it doesn't look right. It looks much better to have the rose take up the various colors through its vascular system either through injecting the dye directly or through the old tried and true cut and cup method. The process takes days. Well, you can actually inject a white variety rose bush as it's growing on the bush, but it's not like grafting a tree. The remainder of the roses will be white unless their stems are also injected with dye. Sorry, I probably gave way too much info. I get excited when I'm talking about flowers.
