bamboo core.

I have been out of the bow making for sometime now because I just had a baby, but during this time I was able to collect a few items to start again. I have cut my horn and pieced my sinew, but have not been able to find adequate bamboo. I have attempted to flatten a few strips but they were too narrow and split. Is there a tutorial or are there people who sell flattened bamboo? Is it ok to use dried bamboo, and if so can I still bend it as green bamboo? I have tried to bend it in the past but it splits as well. There is a very large bamboo farm down the street from me but they will not sell me 4-5" poles under 300$ because they are still planted. Can someone please help thanks.