I don't think you need a sign. If any thing it will draw attention and people will ask questions or try to break in. Your basically admitting that your a grower.
It should be on the entrance to grow area if that is well hidden from view I suppose.
I understand where it could be a problem if you have a bunch of teens or whatever around.
In my case I have two doors that are the actual enclosed secure area, and then on my two rooms inside there I put my sign between them.
If you get to the sign in my case it's time to play that card in my opinion.
Like I said it was shown to be effective in at least one instance; also it was originally written by a lawyer and is apparently legally sound.
The part I added about the Lein machine has been verified via MSP report or similar and is well documented; so I think it best to give the best option on the form.
I say best option simply because it is 24/7 and cops trust it more than the health dept. most likely.
The sign also shows intent to secure the area which could be golden if you ended up in Court over a legal grow.
I run some bad ass gentics and shit; but I never exceed my limits. Ever.
If leo busts down two doors, (either way you enter my place there are two doors to breach to general grow area), and sees this sign it's possible he will pause and read it.
I am not a goody two shoes who thinks his illness makes him above the rest or some horseshit.
I am grateful as Hell that I can grow my own meds with my Docs sig and all that though.
I was given a chance to not have those dirty motherfuckers break my doors down again.
I feel like I owe to myself and the voters to do what I agreed to when I signed up for the program.
So I take a very conservative approach to my own actions.
And I don't worry what others do. It's none of my business as long as I can still grow my meds.