How tall in veg under a 400HPS and a 6ooHPS before flower????

It depends how tall your ceiling is and the amount of light on the side; but generally plants will stretch 100% to 200% once you switch to bloom.
So typicaly a 26 inch tall plant will be 50 to 60 inches tall two to three weeks after flipping.

I'm growing a couple now that easily stretched 300%; so the rule is only general in nature.

If 50 to 60 inches tall is too tall for your area look up LST, which stands for Low Stress Training.

be aware a plant can double to tripple in size during flowering. plants should stay 28-30 in from an air cooled 600w hps....the bigger the plant the more it yields... it kinda depend on the space ur working with...if u have an 8 foot roof id say flower now

Originally Posted by FatMarty

It depends how tall your ceiling is and the amount of light on the side; but generally plants will stretch 100% to 200% once you switch to bloom.
So typicaly a 26 inch tall plant will be 50 to 60 inches tall two to three weeks after flipping.

I'm growing a couple now that easily stretched 300%; so the rule is only general in nature.

If 50 to 60 inches tall is too tall for your area look up LST, which stands for Low Stress Training.

also look into topping

They have already been topped, I was going to wait till the 6 smaller ones that are around 15 inches now, get to 17 inches then flower, I have 8 foot celling.

Originally Posted by steve kelley

They have already been topped, I was going to wait till the 6 smaller ones that are around 15 inches now, get to 17 inches then flower, I have 8 foot celling.

Well it sounds like you should be fine then.
Good luck Bro.

Originally Posted by $waGgEr

be aware a plant can double to tripple in size during flowering. plants should stay 28-30 in from an air cooled 600w hps....the bigger the plant the more it yields... it kinda depend on the space ur working with...if u have an 8 foot roof id say flower now

28 to 30 inches?? Try 12 to 18. FAIL.

from my experience my plants grown under a 400w hps grow 80%-140% after switching to 12/12. But thats just my set up. basically double in size give or take 6"

I keep my 600w about 12-14" away from canopy but I also don't have any heat issues it stays at 74-75 at canopy.