Mother nature will take care of it for you, if you plant it in the ground.

Kay,
I don't have anywhere to plant it in the ground. I just need to know when to stop watering it, and whether to bring it indoors when it gets below 40 degrees.

No need to bring it indoors - mine stays in the ground year around. Do you have a big pot you can plant it in and put in in a protected spot?

From: Chicagobotanic.org comes this information:

CLIVIA CARE IN FALL AND WINTER

In the fall, the clivia�s schedule is similar to that of a Christmas cactus. Stop fertilizing; water only when the foliage begins to wilt; and place the plant in a porch or other cool room where night temperatures drop below 50 degrees. This six- to eight-week rest period is essential for flower bud formation. A shorter cool period could result in delayed flowering.

Once inside, water very sparingly until flower buds appear nestled between the leaves. This might take two months but will reward you with a spectacular bloom just as winter enters its bleakest stage.

When flowers fade, remove the stalk at its base to prevent seed set. In spring, resume normal watering and feeding.

It's in a big pot already. I found a site that said to fertilize it in September (done) and October, then stop watering and fertilizing, and cover it if it gets below 40. It's on my patio, and I moved it toward the back so it gets no rain. That's pretty much all I can do.

Keep us posted on how it does for you.