1st grow purple lemonade

Start of week number 3. 2 of the 5 are stunted for some reason, they stopped growing after the first week. The other 3 have started to take off in growth. Goin to start LST in the next week i think. Humidity is a little lower than i would like but im trying to keep it down to help with keeping the gnats away. Every time i water they seem to come back. Ive tried cinnamon and sticky traps that help but they are still a few every day. Not sure if its worth while to grow the runts out or to remove and fill the space with2 new ones. Any suggestion or comments on how they look would be great!