Introduction to seedlings
A seedling will typically emerge out of its medium anywhere from 4-14 days, usually sooner rather than later. But they can take awhile, and this why a lot of growers like to germinate with a paper towel because they will seed the taproot emerge typically within 48 hrs. And if the taproot shows, then the plant will most likely develop into a seedling. Be careful not to damage the taproot as it's the plants only source of life.
When the seedling pops you’ll probably see 4 leaves, 2 large oval-shaped ones, that look like the shell of the seed (called cotyledons). These feed the seedling until veg, so no need to give nutes yet. You’ll also probably see two tiny fan or “true” leaves.
Cannabis typically stays in the seedling stage for about 2 weeks. They are in veg when the leaves have developed into the classic 5 finger leaf.
High humidity and temps in the 70’s is the best range for seedlings since it’s supposed to be spring.
Temperatures should be spring-like. Around 21° C (70° Fahrenheit) is the best range.
Optimal humidity for seedlings and plants in veg won’t be as critical as later stages, but low humidity may lead to the stomata closing even when the lights are on, which could damage the plant’s photosynthesis process. Keep it around 60%.