Last year I bought "trellis netting" and it was great for my morning glories. They grew from my bottom balcony up the trellis to my upper balcony (10 feet or so) and then kept going up the upper balcony's support.

Here's a picture of mine in action:
http://photos1.blogger.com/blogger/6732/529/640/141_4200.jpg

As you can see, I tied it to the top of a trellis that the vines had outgrown. The top of the netting was attached to my upper balcony.

Here is a link that might be useful: trellis netting

Thanks Containergal, Where did u buy yours? Do they sell in wm,hd,etc? Whats the max height MGs grow to 15 or 20ft?

I ordered mine online from Park Seeds. I don't know if stores have it or not. I also don't know the max height, but mind definitely grew more than 20 feet. They might have kept going if they had anything to grab onto!