Can I Re use soil?

I recycle my soil outdoors. I use the old soil for the bottoms of the containers and new soil for the rest.

By old soil, do you mean potting soil that you had previously used. I think that is a good idea to use as a filler. Depending on the length of time of the old soil, some of the good nutrients have been used up. Some people have used Styrofoam popcorn, plastic bottles, etc to fill the bottom of their large containers too. Happy planting!

I always replace about half of the soil in my pots with new potting soil and add a bit of extended release fertilizer to replace what was used up from the year before. I put what I take out in my vegetable garden to fill in any low spots.