It would be a good idea to buy a copy of Connoisseur's , if you are planning to attempt this, and read Mr. Drake's complete instructions. This produces a distorted, wrecked-looking plant which would be very difficuly to recognize as marijuana. Nitrogen dificiency - add nitrate of soda or organic fertilizer. Older leaves will curl at edges, turn dark, possibaly with a purple cast. Phosphorsus dificiency - add commercial phosphate.
Mature leaves develop a yellowish cast to least veinal areas.
Magnesium dificiency - add commercial fertilizer with a magnesium content. Mature leaves turn yellow and then become spotted with edge areas turning dark grey. Potassium dificiency - add muriate of potash. Cracked stems, no healthy support tissue. Boron dificiency - add any plant food containing boron.