I would recommend investing in cannabis-based nutrients because they will have everything your plants will need to stay happy and healthy. I would also recommend using nutrients more than once a week. If you give them smaller amounts of nutrients once every 2 days, watering with plain water...
If the damage is spreading up from the bottom of the plant, then your plants likely have a nitrogen deficiency. I would recommend using more nutrients, but only a little extra at a time until they are healthy again.
Light defoliation shouldn't really hurt your plants, but remember that any leaves that are green, even damaged ones, can still undergo photosynthesis and help your plants.
Honestly, it sounds like you set your place up excellently to deal with smells, but if you do end up noticing the smell in your house then you can place Ona Gel products around your house to completely get rid of the smell. As long as you don't place any in the actual grow room, which can cause...
If you are worried about leftover salts and nutrients in the soil, I would recommend placing the soil in a smart pot or other fabric and flush it out with clean, ph'd water.
I would recommend using Fox Farms-Ocean Forest soil with some pear-lite mixed in to lighten it. The soil itself should support the plants nutritional needs at least for the first several weeks of it's life. After that, I would recommend using soil-based nutrients like the Fox Farms Nutrient Trio...
A few notes: 1. after 12/12, make sure to change your nutrients to a bloom formula. 2. If the problems are starting from the bottom and moving up, you most likely have a nitrogen deficiency.
I would recommend investing in some ph up&down. Try not to let the ph drop below 6, but fluctuations are normal for the plants to obtain all the nutrients necessary to stay healthy.
The ultimate safe and effective product for pest control during the flowering stage is AZAMAX, I heard it is so safe that you could spray your plants the day of harvest and still have perfectly smokable buds. Hope this helps, and good luck on your grow!
No offense, but I would recommend fact-checking everything your friend tells you. I'm not saying he is wrong, but it doesn't hurt to check. I think he was telling you how to grow weed from clones instead of from seed, because clones off of other plants will grow faster than seeds, and they need...
You seem to know everything you need to have a successful grow, but seeing that you have already started the grow without a lot of the essentials (good ventilation system,fans,etc.) you might have difficulty keeping your plants healthy. Until you can keep your grow room consistently 75-85...
I would recommend using the General Hydroponics Flora Trio if you are using a hydroponic system or coco coir, but if you are wanting to grow in soil then I would recommend the Fox Farms Nutrient Trio.