Well, somebody must be wrong. Assistant City Attorney David Broadwell says unequivocally (at 1:00) that outdoor home grows are against the law, but when Councilwoman Kneich asks where it is so stated (4:39), Broadwell admits that Amendment 64 doesn't make it illegal to grow outside. Broadwell eventually calls for NEW legislation to make it illegal to grow outside.
AND, the City's own new website says
It appears to me to be legal to grow marijuana outside at this time.