Hi Larry, thanks for the tip!
Cheers

It's good for filling potholes in the yard or garden, too!

I reuse mine all the time unless I'm potting up something special and then I use new. And yes, the ruts in my driveway get lots of used dirt.

Thanks, all, for your comments. I mix my own potting soil and have, on occasion, blended in about 1/4 used soil. Seems to work just fine.

If you layer two batches of potting mix in one container, and they are rather different in grain size or peat content, scratch an inch or two of the new mix into the top 2 inches of the old mix, so the transition between the two mixes is gradual.

That will help water migrate easily, and divide itself evenly between the top and bottom of the pot. Abrupt changes between two very different mixes can interfere with capillary movement.

Thanks for the tip, Rick!

Since I am somewhat new to houseplants and very frugal, I have reused my old soil from other plants and put in the microwave for a few minutes just in case there was a unknown problem or bugs. It seems to work for me just fine. In addition, I got this tip from Miracle Gro when I purchased some of their soil which had some flying critters.