Blocking granny squares is not always necessary, but it can be helpful in certain situations. Blocking involves wetting the granny square, then shaping and drying it in a specific way to ensure that it maintains a certain shape and size. If you are making a blanket or other project with multiple granny squares, blocking can help ensure that all of the squares are the same size and shape. This can make it easier to join the squares together and create a more professional-looking finished product. Also, if your granny squares are curling at the edges or not laying flat, blocking can help straighten them out and give them a more polished appearance. However, if you are happy with the way your granny squares look and they are the size and shape you want, you may not need to block them.