A very small fan should do. It also will help if you could uncover them & spend some time talking to them everyday. This sounds silly I know, but hear me out. Plants use carbon dioxide when they grow - guess what humans exhale - that's right carbon dioxide. This is why people talk to their plants - it feels weird at first but you'll get used to it & your plant(s) will love you for it. Remember just because it dosen't talk back it's still a living thing!