Humidity @ 35%

Is there a way I can make my pc growbox more humid? I'm on day three right now nothing has popped out the soil but I'm just curious as to how harmful this could be.

you want it between 60-80 % rh in veg. i don't think the lower is really gonna hurt it, maybe slow the growth.. is your box sealed off with plastic air tight? that helps keep in the moister for sure... peace, happy 420!