Hey, I'm not far from you
Your weak plant should probably be repotted. I suggest you take off the top inch of soil and discard it, as it is bound to carry eggs from the spider mites. Then at least you will know what kind of soil it has. If you use neem oil, I suggest you take a 5 gallon bucket with water and your neem oil, (some people also like to put a drop of soap in with the oil and water mixture), and dunk your plants into the mixture. In other words, put a cardboard over the soil so it won't fall out, and turn the plant upside down and immerse it completely. Dump the mixture after use.

Your plants will grow 2 to 3 times the size of what they went into flowering. I suggest you start "training' them. That is, by using string, tie the branches down, and make each plant lower and bushier.

You can't get a light too close, as long as there is no heat problem, and with a 400w light, 6" is fine...

I invite you to join the WASHINGTON State area.... just cursor down from the main index.

SN