The hare and the tortoise

To cut a long story short, I have two plants under 400w HPS, one of them is 3 weeks behind the other. The big one is 35cm and ready to go into flowering whereas the smaller one is only half that size. I can't think of any way to make the smaller one catch up with the big one.

So, is it okay to just go into 12/12 even though the small one is only like 15cm??

go for it, just make sure they are equal distance from the light.

When they flower they should grow to almost twice or three times their original size. So it shouldn't make much difference if it is half the size before flowering it could catch up or it might not. Really depends on what you want, if you want to put the one into flowering and the other keep it vegging then you should do that till it catches up and then flower her.

Just go to 12/12.

Only thing you can do.

thanks everyone!

you can top the larger one and make clones