Minimum clearance needed around planter?

I have a Genesis v1.6 Farmbot and have reviewed the documentation but cannot find the answer to my question.

I am reusing an existing planter which is currently located against a wall. My available space is quite constrained.

What is the minimum clearance needed beyond the planter (i.e. all around the planter) for the successful operation and maintenance of Farmbot?

Thank you for your help.
Ian