Hi
@Mrs_Larimar! Don't panick, 19°c won't hurt or slow down your plants. During this early vegetative stage, with a 19°c ambient temp, your RH should be between 52.5% and 67.5% for a healthy respiration, so you're actually doing great with your 70% RH. Now, I would still recommend to raise the temp by +2°c, in order to get into the optimal range for late veg & flowering. 21 Degrees would make VPD management easier, check out this chart: http://www.just4growers.com/media/23631/vpd_2degree.gif and it would also reduce the risk of mildew/mold and increase the terps and resine production later. Now in order to raise the temp, I won't recommend the heater approach, because it would mean buying an expensive growroom heater that you can plug to your thermostat. No, instead I would add some more lights. Even some cheap IKEA full spectrum bulbs, just to get a better coverage + gain a few degrees. Your babies should appreciate. If you don't or can't add even the smallest bulbs, then you could consider reducing your extraction or grow in a sealed environment (IE no extraction but this requires supplemented CO2). Hope this will help, happy growing (love that Rowenta fan by the way, I've been using the same for a while! Too bad it doesn't auto-start!) 👊