I have several flower pots outside and even though I use soil especially formulated for containers, the soil still gets hard and compacted in the pot. Regular gardening tools are too large to get into the pots to loosen the soil.
So, last night, with my mom in tow, we went to the dollar store and I bought two dinner forks for $1.00. I use the fork and rough up the soil and aerate it. I gave the other fork to my mom because she's been using their everyday dinner forks. Yuck!