smoke24answered grow question 4 years ago At 4 weeks old you can certainly start fully watering them. Looks like you are growing in soil and using organic nutrients, that being the case you don't want runoff when you water, give her just enough to completely saturate the pot, then don't water again until the top inch of soil is dry. You will also want to keep an eye on your soil ph to make sure it stays where it should be. Happy growing.