BTW @ wk 4 I too would use a light bloom booster, but a very, very small amount with this strain. Also, one reason it looks so sparse is because it is a sativa. You are likely looking at 10-12+ weeks til mature & it will be a month before they start to fill out. They will never be thick & dense, but will get big & airy. Likely you will get frustrated with them & never grow a sativa again, except maybe as a head stash, and even then, what a pain in the ass...