Hi Robinia, Don't stop watering your acer, if I was you I would get it out of the pot now - it really depends if you care more for the plant or the pot, if it was me I would save the plant (bit of a plant addict me), it will be a pig of a job to get it out of your pot, but trying to get it out is preferable to not watering it! If you get it out or smash your pot, just make sure you keep it watered in the 1st year as it will be root bound and even if you tease out the roots, it will take some time for them to spread out. I expect you know that acers like a sheltered spot. Good luck with it. H.