tall cannabis plants
On the other hand, if your plants appear tall and spindly for their age at three weeks, they probably require a little trimming to ensure a nice full leafy plant. At three weeks of age your plant should have at least two sets of branches or four leaf clusters and a top. To prune the plant that has started from cannabis seeds, simply slice the top off just about the place where two branches oppose each other. Use a razor blade in a straight cut. If you want to, you can root the top in some water and when the roots appear, plant the top in moist soil and it should grow into another plant. If you are going to root the top you should cut the end again, this time with a diagonal cut so as to expose more surface to the water or rooting solution.