Yes, definitely keep any grow operation under lock and key unless you have a very well trained family, and even then it gives them a backup to resist pressure to look in the room/cabinet.
The standard response to an unannounced visit from LEO is to step through the door and close it behind you, then the standard reply to "May we come in?" is "Why do you want to come in, officer, we can talk her just fine." When they push just a little bit say "I'm sure you wouldn't let me in to your home and come in just because I walked up to your door and asked to come in,would you?" Then when they argue, ti is "My privacy is just as imprtant ot me as yours is to you, so without a search warrant, I will talk to you out here but you can't come in just because you don't want to talk out here."
REMEmBER IF THEY HAD ENOUGH FOR A SEARCH WARRANT THEY WOULD ALREADY HAVE IT WITH THEM AND WOULD HAVE SHOWN IT TO YOU IMMEDIATELY INSTEAD OF TALKING OT YOU AND WOULD HAVE PROBABLY EITHER PUSHED THEIR WAY PAST YOU OR TOLD YOU TO MOVE! They do NOT fool around being nice if they have enough for a search warrant.
A locked door or cabinet is still a good idea because even if you let them in, they can't USE and thing they find if they go any further than what is in plain sight from where you ask them to stop unless they have a search warrant.
If you grow where it is illegal or if you have ANYTHING that might be illegal or imply that you may be illegal, do NOT let them into your home or other property. It is vital that EVERYONE connected to your home or property be firmly and thoroughly taught this!
This advice comes from having been the victim of an overzealous cop who claimed to be my friend but was really trying to prepare for a run at Sheriff by setting me up because I was an outsider in a small rural town. It is also the result of training as a LEO both in the military and outside. Also, do NOT let just anyone in even if they are with a friend until you KNOW versus think you know who they are and what they are doing there.
newgreenthumb, I'm glad you are back and running. I'm getting ready to sprout some bagseed in addition to my good stuff. If it turns out as good for me as it did for my friends mother, it may become my mainstay.
Good smoking and Happy Thanksgiving to all.