Clay pebbles at the bottom

Totally works. I do it with hydro, as well as soil/coco in pots. Thats in normal pots. In fabric pots- ur trying to help air flow in a pot made of fabric and air??? I dont like keeping my pots directly on the ground, so have them on low shelves or pot stands, or even just bricks to keep em off the ground and allow air flow under the pots. In a fabric pot-lifting it off the ground will do the same thing as adding these. If u want to use them to help reduce the weight of the pot as well as decreasing the volume of the mix that holds nutes and water, then its fine. Adding more perlite to the mix would help more than adding half an inch of this in the bottom of a fabric pot if your soil mix is a bit dense and low on things like perlite and high in peat. So would lifting pot off ground for air flow. Now I have said all that, it wont hurt the plants in any way at all if you do this. It may actually help more than im expecting it to, but in fabric pots ive never felt the need to line the bottom with anything to help drainage. Plastic pots yep. use it all the time. Love em in hydro too. But hey it wont hurt so mind as well try it and see right?