After my inaugural 1-plant soil grow last time, I decided to try a hydro and a soil grow simultaneously and see the difference growth rates. They are Afghani Indica and I ended up with two in soil and one in a GH Waterfarm using the Lucas formula. All were germinated on 2/05 and I am going to switch to flower in two weeks. I am trying to stick to a three month cycle from germ-harvest. They seem to be doing well, but the hydro is almost twice as much growth, but interestingly the leaves are HUGE! Why is that? Does this seem like reasonable growth for a two month old?
more direct application of o2 and nutrients to roots. less resistance in the medium so roots don't have to develop as thick. this allows vegetative growth to begin sooner and at a much more rapid rate.
Is that why it's not reaching as much for the light above? The soil plants seem to be stretching out a lot more, but the hydro is just really wide and low. I am finding hydro to be much less trouble then soil.
I don't know the specifics on your grow environment and feed. without it I can't really say anymore for certain. If they are seed they could be different phenotypes. could be some kind of stress causing the stretch. likely competition for light. because they have to set roots in soil it takes a little while before they can start growth. your hydro can start almost immediately. then the soil plants have to try to play catch up as you move your light with your more rapid growing hydro plant leaving soil plants a little stretched. keep your light as close as possible and it should level out if it doesn't, choose one.
i've always noticed quicker growth in hydro versus soil. probably the difference in size is because of your container size. your hydro pot is bigger, which allows for more roots. the more you have going on downstairs, directly effects what goes on upstairs. it's like bonsai trees. keeping the root-mass small, keeps the trees little too.