Athosanswered grow question 6 years ago Watering in party cups is easy, just give them a cup of water (aprox 200 cc), that should saturate the soil and last you for 4 to 6 days if everything is right, when the cup feels light again, you repeat the process. If the seedlings are stretching, then the light is too far. I can't see any yellowing in the pictures, just be sure to let the media dry up before watering again and it will be fine.