I've read that Ghost Train Haze takes 10 week...

8 more Weeks and Harvest is near^^... i hope you got the Patience.Temps and Humidity looks fine, and yes you can strt some PK boost, as alwys start slowly and look how she responds, then you can rise the dosage every week . Happy growing

I would say to boost the PK now seeing as you did not at the start . Usually this is done to help facilitate the transition from Veg to Flower this way your bud sites form up quicker and nicer . So I wouldnt be to concerned about it tho your plants are forming up nicely and arent showing any signs of stress . The one thing I highly highly recommend is lowering your RH (humidity) 80% is wild for flowering you want this number to be below 45 % at this point and every week forward your going to wanna lower it 5% until you can get to as low as possible . I say this because we wanna avoid getting bud rot or mould ! After all this hard work and all this way you've come I'm sure that's would be the last thing you want to happen to you're plants ! I might also consider raising your night time temps to no lower then 15 degrees your plants going to grow more slowly during photo syth periods because its about to go dormant you're optimum temps are 26 c day and 18 c night for flowering . You must remember that cannabis is an annual meaning it grows from spring to fall and once it gets below 15 degrees it pretty much stops growing all together and gets ready to lay dormant for the "winter" months. Over all in your great shape and well on your way to getting some kick ass medicine . I would just adjust your humidity and your night time temps and you will be rocking and rolling ! :) I hope this information is helpful on your quest to the finish line ! -Happy Growing!

First get an EC/PPM meter. During flower you want your feeds between 1.4 and 2.0 depending on strain. I usually use PK boosters when the buds start to fatten up and there is no more vertical growth, usually at the 5th week of flower.