If you consider that it takes about 1 to 1 1/2 weeks to get from nearly all cloudy to your desired amber %, and that your flush period should be about 1-2 weeks, then it is actually a useful way to gauge your flush time without actually knowing the exact date on which the crop is due to come down. So yeah, it will save you the 'it's not even close!!!' headaches.
I think at the end of it all, the presence or absence of calmag in the watering solution is less important than during growth- maybe cut the ferts first, then cut the calmag later, in the last week. I don't know what would be perfect, but that would be logical at least.
stinkyattic Reviewed by stinkyattic on . Problem 2 weeks before harvest? I have this Greenhouse Seeds Fem. Trainwreck. It is 7 weeks into flowering, and probably about a week and a half to 2 weeks from harvest. I was feeding it Canna Terra Flores N-P-K 2-2-4, and Plagron Green Sensation Top Activator 0-9-10, and water (alternating between each watering). For the last week and half however, I stopped using the water, and alternated between the two nutes. A couple days ago I noticed the leaves around the top of the plant began to rust and turn purplish Rating: 5