Special Kush #1

I am having more trouble with this grow, than my previous two attempts. The larger plants was transplanted last week, and I have now topped them and pruned some of the lower growth that would be in the way of watering doing flower, when I can not just take them out of the grow room. The smallest plant.. I completed fucked doing the transplant :( I have had a lot of problems getting the other three plants out of their pots; ending up having to use a blunt knife to loosen the dirt from the sides of the pot.. I tried to use the knife immediately on the last seedling, but somehow I ended up losing the bottom 1/3rd of the root system / dirt of the pot. It was smaller than the other plants, but showing a lot more roots going out the bottom. Which is why I choose to transplant it now, rather than wait. Edit: I have been doing dry transplants previously, without problem. Having a dry medium seems to pull away from the sides of the pot, but this time it wasn't enough. When I couldn't get the plants out after several minutes of trying, I tried to wet the dirt hoping it would loosen the plant from the sides. Neither option worked. I have transplanted several plants from these same clay pots, with a dry medium without problem; so I am not entirely sure what is going wrong this time. For next time I am going to stop using clay pots, and just get some regular plastic pots; that I can just cut up if push comes to shove :)