Can I cut my plaid drapery fabric on the vertical?

I have a piece of plaid drapery fabric that I want to use to make 2 valances for my bedroom windows (2 windows). Would it be ok if I cut the fabric on the vertical length? I need to add a smaller section to each side of the main piece (according to my sewing pattern). If I cut it vertically, I would have enough fabric without having to add the extra side pieces and not have the aggravation of trying to match those darn plaids. Would the valances hang right? Thanks.