That could mean a room, a garage or even a backyard, as long as it’s out of public view.
You have to be careful about relying on a reporter for this kind of thing. It is always best to read the full text of the initiative/law for yourself. In this case, the reporter is wrong. Mz Sanchez is looking at the part of Section 36-2859 that deals with the commercial establishments :
"THE CULTIVATION, PROCESSING, TESTING, STORAGE, MANUFACTURE OR SALE OF MARIJUANA AND MARIJUANA PRODUCTS SHALL TAKE PLACE AT THE PHYSICAL ADDRESS APPROVED BY THE DEPARTMENT AND WITHIN AN AREA THAT IS ENCLOSED AND LOCKED IN A MANNER THAT RESTRICTS ACCESS ONLY TO PERSONS WHO ARE LEGALLY PERMITTED BY THE MARIJUANA ESTABLISHMENT TO ACCESS THE AREA. THE AREA MAY INCLUDE A GREENHOUSE AND MAY BE UNCOVERED ONLY IF THE AREA IS ENCLOSED WITH SECURITY FENCING THAT IS DESIGNED TO PREVENT UNAUTHORIZED ENTRY AND THAT IS AT LEAST EIGHT FEET HIGH."
For "ANY UNLICENSED PERSON", (in other words, not a dispensary or retail establishment) the rule is different, and is found in Section 36-2866:
EXCEPT AS OTHERWISE PROVIDED IN CHAPTER 28.1 OF THIS TITLE, ANY UNLICENSED PERSON WHO PRODUCES MARIJUANA PLANTS PURSUANT TO SECTION 36-2860 WHERE THEY ARE SUBJECT TO PUBLIC VIEW WITHOUT THE USE OF BINOCULARS, AIRCRAFT OR OTHER OPTICAL AIDS, WHERE PRODUCTION IS PROHIBITED BY A PERSON WHO OWNS, MANAGES OR LEASES THE PROPERTY WHERE THE MARIJUANA IS PRODUCED, IN ANY OUTDOOR AREA OR OUTSIDE OF AN ENCLOSED AREA THAT IS EQUIPPED WITH A LOCK OR OTHER SECURITY DEVICE IS GUILTY OF:
1. FOR A FIRST VIOLATION, A PETTY OFFENSE PUNISHABLE BY A FINE OF NOT MORE THAN THREE HUNDRED DOLLARS.
2. FOR A SECOND OR SUBSEQUENT VIOLATION, A CLASS 3 MISDEMEANOR.
The "PURSUANT TO SECTION 36-2860" makes this very explicit, as it is the section about personal use, cultivation etc.