Mosos leaves are bigger than normal when the plant is young, but the culms should be able to support themselves. They also like full sun, and should have had it long ago; maybe they are weak from not enough sun exposure. If you want to gently put a little stake in the ground and tie them, that would be the best way to provide support for the culms. Can you post a picture? Here's what a 1-year old moso seedling should look like:

Here is a link that might be useful: {{gwi:412927}}

Thanks Kudzu. Mine look similar except that the culms are not supporting themselves. I will try to post a pic early next week when I get my hands on a digital camera, or I can try taking one tonight with my phone. How long would you recommended they need to be acclimatized before being placed in full sun?

What kind of sun do you get? I'm near the Canadian border (Greater Seattle area) and my moso have done fine out in full sun since they were small. Unless you get a withering sun, I'm not sure you even have to worry about acclimatization. The key is to not let them get dried out. They can handle the sun.

Here is a picture on my potted moso. I live in Toronto, so I think the summer sun is hotter here than it is near Seattle.

{{gwi:412928}}

edbtz-
If you want to be safe, give it bright light and some sun for a week and see how it does, but I still think you can get it into full sun pretty soon. However, I can't tell how big that pot is and it might be time to repot in something bigger.

Too wet and too little light might cause those symptoms.
Be sure to harden it off if going outside.