the first two plants show no signs of heat stress or nute burn on the tips of the leaves... why is everyone agreeing that its nute burn?>? i've had this problem before and found that when i added MORE A (vedging nutes) the leaves started to grow normally again. this could be due to your plants not having enough vedg nutes because your trying to encourage buds by adding B nutes... be cairfull though. if you do not reduce your B content when you increase your A content you WILL get nute burn. which looks like the tips of your leaves are dead...... ps. fuck know's why everyone eltse is saying otherwise...