they turn yellow as the plant uses up the chlorophyll and nitrogen in the lower parts of the plant ... normally, nitrogen isn't added in flowering (it is said to actually impede flowering) ... most flowering-type nutrients have at least some nitrogen in them, anyway ... I wouldn't worry about it, unless the plant takes an obvious turn for the worse ... with a sativa, you could still have a long way to go (my Willie Nelsons went 14 weeks, and could have used a couple more) ... :smokin:
the image reaper Reviewed by the image reaper on . sativa is turning yellow Here is some pictures of my Sativa its in four weeks into flowering , the bottom leafs are turning yellow rapidly working it way up an falling off. Their getting plenty of potassium ,phosphorus .ph level is 7. Rating: 5