Tell the police to reread the law.
Plants must be kept in a locked, secure room.
Now officer, you wouldn't want me to break the law by removing my plants from their legally protected area, now would you sir?
Now on a serious note,
Don't even tell them that.
Your conversation should be limited to-
No, I will not talk to you officer (If they have cause to suspect something illegal, that's what judges and search warrants are for). Sure, they can ask you nicely to bring all your stuff down for an inspection, but asking is about all they can do, and you're under no obligation to comply, nor are you obligated to answer any questions simply because the police are asking them.
The most important part of this post is the NO I WILL NOT TALK TO YOU OFFICER.