More Sun= more black. other wise all the leaves will be green.

Thanks for your response. I have illustris in the same spot, sunny southfacing patio door and it has its coloring. I don't think I can provide any more sun than it is already getting so will see what happens.

My illustris is much less sensitive to less than full sun conditions. Black Magic (and Black Runner) both seem to need really lots of sun. Illustris is deeper black in full sun too, but not as much as those two.

Hi
That has been my experience also. The more sun the darker the leaf. I grow these in every conceivable situation from standing water to moist and in pots and now in moving water in dapped shade. The largest darkest leaves are in pots with rich soil in standing water with dappled sun
A surpise in the moving water ,the runners are actually climbing the wall and rooting directly in the expanding foam that I use for a waterfall surface. Had no idea they would "vine" lol gary

Many people experiece this problem. I've received one email today already asking why the plant turned green since it was brought indoors. Depending on your zone, you can leave it out all winter. If you are in colder than Zone 9, it will go dormant but it will return in the spring. We're in 7B and have left them out all winter and had them pop right back in the spring. Some don't recommend leaving it outside in colder than zone 6. Otherwise, just be prepared to live with the green leaves. They will also become smaller during the winter. But as soon as you return it to the direct sun next year you'll get back all you've lost. I've had the plants actually turn blue under the right light conditions. Quite stunning!