I have been using MG Soil for 4 weeks now, (yes germinated it mg potting mix) using no perlite and just adding water when the top is dry, and it's looking very good, I have a single 18w CFL at it for the time being as I was going to grow with HPS/MG (250w) after test it produced a bit to much heat, so ill stick to cfl's till I can sort that out. When I purchased MG, I was thinking, that it, my expensive seedling will die, you know what? it grew.. grew like a crazy m*F*
Use mg, but also add 25 - 40 % Perlite, if you don't have accessors to perlite you can always add sand ( make sure you boil it to clean all the salts ) it's not as good but absolutely will do the job for fair drainage. If your in the UK, they have perlite in B&Q & Homebase. Make sure you don't buy MG perlite or any perlite with nutes.
Interims of flushing or " clean smoke " - No, you can't flush it, It will activate all the nutes and yes you'r plant will suffer or even die but what you can do is this. Two days before harvest, cut you plant off at the bottom and place the bottom stem it into a glass jar full of clean 6.5ph water ( no nutes ) after a few days the plant will be flushed, just a bit differently, works great, most MG growers do this.
I don't really get it why people hate MG, I think its like cheating in terms of growing so it's really easy for n00bs but " Pro " growers use just soil and then buy expensive nutes and overcomplicate a simple grow, yes its more efficient then MG, but mg is way more simple and just as good. With MG i water once every 1-3 days and that's all. So simple. I think it's spread like this. Once inexperienced grower over watered the plant and killed it, told his buddies MG is bad and will kill the plant, those buddies told other friends and so it's spread like a disease. I see plenty of MG grower that read before doing anything and have success.
Here's my Ak-47 in MG (4 weeks) - Look's ok to me
I'm in the UK.
