Starting seed in grow-box on heat pad

Hey all. I have a handful of seeds starting in solo cups. All but 1 of 8 sprouted and are growing. My question is how long do I keep them in the grow-box under 6500k CFL? Sprout to 2” tall? When to start fertilizer? What is next to identify the seedlings are ready to go to 3 gallon cloth home?

Thank you so much!

You’re plants appear to be stretching, that’s usually from not enough light intensity. You could probably lower your light some for now. Then just bury the stems a little when you transplant. You should also place your clear cups into colored cups to keep too much light from hitting your root zone.

I usually wait until the plant is about as big around as the container it’s in to transplant. But a little sooner or later isn’t a big deal. Nutrient timing will depend on what you’re using for growing media. An inert media will need nutrients as soon as cots start to yellow. A well amended soil can feed for quite some time, some even the full length of grow.


Thanks for the reply. Yeah they are stretching for sure. I use 6500k CFL @ 100w about 6-8 inches above the plants in a grow box. I spray them down at night then take the cover off for the day. The bud is from white widow autoflower probably a couple more weeks.