i have 4 plants which are sitting at 300 ppfd and they arent stretching much and im about to flip them to flower, for the preflowerimg stage (first 3 weeks of flower) should i keep the ppfd low for them to stretch? or give them the ppfd needed? im scared that they wont stretch if i give them the ppfd needed right now
added co2, at 900ppm
should i pump it up to 600ppfd and see what happens? or wait for the 3 weeks to pass?
I dont know that anyone can give you an exact formula for your PPFD and C02 will change it. I suggest contacting your light manufacturer and see what they recommend dont for get to tell them you use C02, Most importantly make a log book and keep an eye on the plants.