CanGroIt is spot-on about waiting for the "stretch" to be over before you stop training to fill out the screen as much as possible. I usually wait until I no longer get enough "stretch" growth to allow me to train back under the screen. The plant itself decides when that is. Usually between week 3 and 4 of the "flower stage" (meaning 12/12 and change in nutes to bloom or flower type). That is why it is important to wait for the screen to be at least 1/2 to maximum 3/4 full before switching to flowering stage. This is how you get the most productive results from the space you have. (more buds)
As far as "haircuts" I prefer to basically eliminate any leaves or buds that are more than 1" lower than the screen at the end of the flowering stretch. This does a couple of things (IMO). First it will definately make more room for air circulation to help prevent problems like mold and mildew. Also I believe it forces the plant to concentrate on the remaining plant above the screen. The benefits gained above the screen will far outweigh the little bit of loss from the trimming.
Remember "you can observe a lot just by watching" are very important words to live by particularly when learning SCROG.
Last edited by Max Blast; Mar-07-2011 at 12:55.
Never argue with a fool: 1) People watching can not tell who is who 2) They will drag you down to their level and then beat you with experience