Calcium and silicium missing?

if you are going by color of leaf, turn off grow light and shine some normal 5000-6000k light bulb in there and re-assess. The terminals look like that at beginning of flower... should see some tufts of hairs soo. Feeding is about providing enuogh... a good rate of nutes, actually. you cannot force feed a plant. you can increase transpiration, therefore how much the plant drinks, through the environment and how much light you provide -- amount of atmospheric co2 has a say too on all of that too. light and co2 are the rails.. not feeding. find a good balanced mix, and stick to it. make 1 change at a time and observe... otherwise you have no idea what caused what if you do 3 new things at once. if you have any issues it is small and slow moving... i'd get a beter idea of leaf color with more complimentary light spectrum, if that was concerning you. The twisted stuff at terminals is just part of switch-over from vege to bloom cellular growth. Probably won't gain much more height. even though you are in soil, you can gain a lot from calculating ppm's of each component of mix - n/p/k/Ca/Mg/S. the last three will vary by garden a bit due to tap water differences. the first three should be fairly consistent and values backed by real research, not "bruh science". Check out table of my ppms in any diary, just about any week. it'll give a good ballpark to shoot for. now, you are in soil, so must consider the contents of teh soil... at week 8, probably relying almost completely on your fertilizing. At this point you can safely treat it like a soilless grow. irrigate each time with a 1.3-1.5EC mix (650-750ppm, as calculation of EC is not universal). get 10-15% runoff waste -- do not let it re-absorb. toss it outsode or down the drain. We don't choose what the plant eats... it doesn't selectively eat... so we must provide in proper ratio, proper rate, proper pH. some give and take in all of that, of course.