4 plants in a closet in a room.

Keep the doors closed.

Avoid commercial grower-sized solutions.

Read the available FAQs on carbon scrubbers.

Small grows can get away with masking the smell. I like a combo of chopped onions left in the kitchen...nag champa burning near the grow room, but not IN it, and me walking around with a cigarette anytime someone might be or is expected to stop over. But thats me and my area...threat of exposure through aroma is minimal.

However, better peace of mind would come from knowing the bouquet of your plants is being removed from the room's environment.
Again, hit the FAQs...lotsa good info there for either a good model carbon scrubber to pick up...or small scale DIY numbers that work plenty well for the personal usage grower.

Good growing and please be sure to post any solution you end up employing for your grow. :smokin: