I can't remember the width of the panels for my standard size patio door but I know I did buy regular panels and sewed them together. I think I must have purchased 3 panels and used a half width of the third panel on each of the full ones. They turned out just fine. I was lucky and found the panels on clearance at Bed Bath and Beyond.
Here's a couple pictures of mine
{{gwi:1545431}}

I just saw some nice looking ones with texture at Target. I was surprised that they looked nicer in the store than on-line. I think they were 50" wide and were $24.99 each.

JC Penney;s has big long panels too. I think in a few price ranges,

Love the name Sadie!

Thanks everyone for your help.

Badgergal - That's exactly the look I'm hoping for. Are your panels lined? If so, did you open the end hem on the panels and then sew together the panel and the lining separately? Do you close the panels? Any problems with that?

Sadie, I went and looked at my curtains. I see now that I actually used 2 panels on each side. Each panel is 54 inches wide. More width than I needed but I guess now that I didn't want to cut one panel into two widths.
My panels are not lined. I just opened up the opposing side hems and sewed them together with a very narrow seam and then overcast the edge.
I have no problem drawing the curtains across except for getting the folds to look "perfect"- that's partly because I have all that extra fabric width. I used to close the curtains everyday because the door faces south and the sun could be too much, but we have replaced the original door and now have blinds between the glass. Now I only close the curtains at night if we have guests for dinner and I want it to look a little fancier in the room.

Just curious did you measure height? I have a large sliding glass door that I was trying to get panels for when I moved in and unfortunately the height of them made it impossible to buy from any stores (I looked everywhere). I had custom panels priced from JCP and a local blinds/window treatment co & both came out at well over $1000 for a single panel to draw across my windows (with the rod. and my door is in a corner so it had to be a single panel pulled to one side). It sounds like you're planning to sew something yourself but just thought i'd chime in about height.

Last time I was at JC Penney's the salesperson mentioned that with the grommit curtains it is not necessary to sew the panels together but to simply overlap the first and last of the grommits. It's hard to explain but perhaps if you go into the store you can see what I mean on display. It seemed a lot easier to use standard sizes with multiple panels. That said, I don't use any grommit tops in my home as I prefer a more traditional look. It does seem the best solution for wide patio doors because they also stack back without taking up a lot of width.

You can buy semi custom drapes from american blinds. They come in standard widths and AB cuts the length to your specs. With that width you will need a center support which when closed will have a slight gap in the center. An alternative would be to use a decorative draw rod with rings but they can get pricey.

Pottery barn carries some, as does Plow & Hearth and Touch of Class.
You can find other colors by searching 'outdoor grommet drape'.
You might also check Overstock.

A tip: try to use a solid rod where you want the grommets to open/close. If you use an expandable rod, the grommets with catch at the point where the rod diameter changes.

Here is a link that might be useful: Drapes