I'd add the extra CFLs right away, watching your temperature of course.
Very often, your tap water has enough calcium, but unless you are sure, it is best to add a supplement. This is where knowing your EC numbers is helpful. I have grown successfully in hydro with nothing but Canna Aqua A+B and city water, but I am lucky that my city has GREAT water for growing pot! Not everyone does
Without calcium, you will notice that the low leaves start to show pale yellow blotches that are irregularly shaped, and eventually die. There's no way to get around it; you need Ca- you just have to find out if your tap water + nutes are enough, or you have to go buy some. Even a halfway decent garden center might stock some type of suitable Ca supplement. Tomatoes and squashes need lots of it so they don't get blossom end rot- ask the garden center people how to avoid that, if you don't want to seem stoneriffic.
stinkyattic Reviewed by stinkyattic on . Germination Pictures! Am I on the right Track??? So I soaked my rockwoll cubes in 5.5-6 ph water for about 20 hours and i just put the seeds (hindu kush and 1 thai stick) with the root down and the seed pointed up.. i have a lid over a drainable bowl.. is this too much light for them(42 watt cfl for now)? or should it be dark until they hit the top of the rockwoll? Also I have one seed that germinated and i dont have a fifth rockwoll cube ready? is there any advice? can you put two in one and see which grows the best? Rating: 5