Length is an obvious factor when you’re trying to cover a sliding-glass door, as is keeping the drapes out of the way of the door as it slides along its track. While tension rods exist that expand to very long lengths, they place the drapes too close to the door -- increasing the chance that the drapes could get caught when you open or close the door, because the tension rod fits in between the side of the door frame.
A regular curtain rod held by brackets on the wall above will move the drapes a couple inches out and away from the door. The rod itself should rest on or snap into the brackets instead of being permanently installed in them. Rods that are not easily removable from their brackets are meant more for drapes that have hooks, which don’t require removing the rod from the wall when you install the drapes.
Grommet drapes are among the simpler types of drapes to put on curtain rods; all you have to do is slide the rod through the grommets, weaving it back and forth until all the grommets are on the rod. Because the drapes don’t have a separate mechanism to pull them open, such as string, they have to be able to slide along the rod freely. The rod you’d use for this is called a stationary rod, which Factory Direct Drapes says gets its name from the fact that it doesn’t have moving parts that connect to the curtains.
The brackets holding the rod up will prevent the ends of the grommet drapes from sliding off, but if the rod just sits in the brackets and doesn’t snap in, the rod can gradually slide or get pushed out of one of the brackets over time, with repeated friction from the drapes sliding across. Decorative finials -- those end caps you see on a lot of curtain rods -- not only make the rod look like an actual curtain rod, rather than a metal stick over your door, but they also provide a little more resistance to letting the ends of the rod slide past the brackets.
Size and Weight
As with anything else you hang, take size and weight into consideration. Curtain grommets are generally wide, to accommodate curtain rods with different diameters. You should still double-check that the grommets will fit over the rod you’ve chosen, though, just to ensure you haven’t overlooked something. Also, the curtain rod you choose must have brackets that can hold the drapes you want. Most drapes are fairly lightweight, and a rod that’s long enough to fit over a sliding-glass door should be able to hold the weight of a curtain that big. Like the grommet size, though, double-check.
The curtain rod package should have a weight limit on it, or, if you order online, the website should have some sort of measurement. Finally, check that the center support bracket sits above the center of the sliding-glass doors, where the nonmoving door begins. The center bracket will prevent the grommets from sliding past, and you want to be able to move the curtain back far enough to get out the door.