Haven’t tested how long the effects last for, but I was having trouble keeping my humidity above 42% (with two humidifiers in my livingroom) and accidentally found a way to raise it. I’m on day 3 of germination and my pod seemed dry so I took a spray bottle I had on hand and misted it lightly. When I went to check on the temp & rh level 15 mins later, the humidity had jumped up to 51%! So I sprayed a light mist on the walls and when I checked again the humidity had went up to 62%!
Might try a wet cloth next since the moisture will last longer. I know a small desktop humidifier is an option, but I’m holding off til I’m sure I need it (we only have 1 more month of winter here before wet spring rolls in).