Not growing - stacked

They look dry what’s your real active humidity?

Until now i dont give any nutrients

Definetly canna terra you have used and not Coco plus ? Canna terra has an EC of 1.2 when new so that should be more than enough to get through the seedling stage at least . Maybe add a small dose of nutes and see how they react . If you have been feeding for 4 weeks nearly, maybe there is not enough nutrients left? I use Coco so could be wrong . But a small feed with the correct PH I would try.

hey there Olffgrow, growth rate is determined by VPD which is the relationship between humidity and temperature. Right now , i have no data but my guess is that you're way too dry : you should be around 70% RH , looks like you're around 30-40% based on the way the plants look. Try raising your humidity with a mister, an evaporative cooler, or simply by spraying the plants with water up to six times a day. Just be careful about light burn if some droplets collect on the leafs. Hope this helps ! 🚀