What's up with this little girl ? Very slow growth at Week 5. Is this normal?

Could just be a slower plant, but i think at least a little bit of the slow growth is self-inflicted. Couple things.. early lst can be a bit shocking. It won't always cause an issue, but eventualyl your run into something negatively impacted by startin LST almost immediately with a seedling.. the long initial steam says ramping up light was a bit late, that could contribute to slightly slower growth, too. consider the time since the light was properly adjusted and it probably make better sense relative to growth seen rather than the entire time since sprout. Could probably give it a tad bit more light. Internode is still a bit long. Internode length is an excellent way to dial in a light relative to to all the local variables of your garden. The math will get you in a the ballpark, then the reality of what is in front of you dials it in after that. Think i agree that the watering habits are suspect based on the picture. Could be a contributing factor. 1) fully saturate with 10%runoff... always fertigate with a well-balanced formula. The runoff prevents buildup and is essential to maximizing soilless growing outcomes. 2) wait for top to start to change color and repeat. There's some variabiity in how long you wait between, but do ensure some decent amount of wet-dry cycle occuring. Don't let it dry so much it wilts, don't water too soon that the roots are always soaking wet.. fairly wide range of "acceptable" here I'd still stick to a more pronounced wet-dry cycle early on to promote thicker root growth, then if you want to push harder later with less dryback as you enter flower, you'll benefit more from the thicker root mass, too. You'll want 33% perlite or similar in coco coir for a proper gas:Water mixture around roots. I prefer vermiculite because it also adds some plant-available Si. A proper constitution also makes 'overwatering' nearly impossible. you'd have to sit there and run water through the pot for 10-15minutes before you see the plant droop due to O2 deprevation, lol. As long as you don't water too frequently, should never have a root zone problem related to watering practices. in the end it's really not far off from robust growth. Give a bit more light (if recently adjusted, observe and react as needed)... use orthodox irrigation habits, and it'll shape up quickly and get a little faster growth going forward. can't do much about the lack of drainage/aeration amendment,s but that's not going to derail anything on its own. Better than sphagnum peat moss with no perlite... that holds more water, so it needs 50% perlite or similar and would be that much 'wetter' around the roots for a longer time... when properly constituted 1:1 it has similar gas:water mix as coco+perlite 2:1. The myth that coco is somehow betteer in this respect is more a matter of people not constituting their media properly and attributing the wrong cuase to effect..