Hi,
I just started six that are in poly bags, I filled them with hydroton and set them inside containers. I did it so when I go to transplant them to waterfarms it will go easer on them. Just slit the bottom of the bag.
I am watering them 24/7 and the bags drain fine. They would have stood by themselves but I needed something to hold the drip system in place. I drip on either side of the 3' rockwool cube. just enough to keep cube moist and supply constant source of nutes to roots. Pics in my Cabinet grow.