As they get bigger, we gently run our hands along them to help strengthen the stems. This simulates the breeze they would be resisting if they were outdoors, the resistance is what triggers them to thicken their stems. Some people set up oscillating fans for this which works really well too.
Our seedlings have grown quite a bit since our last entry. And our grow room is getting super full.
It won't be too much longer till we get these little guys in the ground!