HOW TO REVITALIZE COMMERCIAL SOIL MIX IN POTS ???

I HAVE 50 OR SO POTS FROM LARGE TO SMALL ALL FILLED WITH COMMERCIAL POTTING MIX (SUPERSOIL OR MIRACLE GROW) THAT IS A MIXTURE OF FOREST PRODUCTS, SAND, PERLITE, FERTILIZER, ETC. IT SEEMS LIKE I HAVE USED 50 BAGS OF COMMERCIAL MIX AT $6.00 PLUS FOR EACH BAG. THE BIG QUESTION IS WHEN I WANT TO AMMEND MY POTTED SOIL, WHAT DO I ADD TO IT BETWEEN PLANTING SO THAT IT RETAINS ITS INITIAL QUALITY? I KNOW THE PERLITE AND SAND WON'T BREAK DOWN BUT ALL THE "GOOD STUFF" DOES BREAK DOWN AS EVIDENCED BY THE SOIL IN THE POT DROPPING TO A LOWER LEVEL. I'VE COME TO EXPECT THAT A POT WILL DROP 2 INCHES IN A YEAR SO JUST ADDING FERTILIZER WON'T WORK. I'VE GOT ONE POT THAT IS 3 YEARS OLD THAT HAS DROPPED TO 50% OF ORIGINAL FILLING. THIS DROP IS NOT ALL SOIL COMPACTION - SOME SMALL AMOUNT IS. THE SO CALLED COMPOSTED FOREST PRODUCTS DISAPPEAR AND ARE NOT AVAILABLE FOR PURCHASE IN OUR AREA AS A SEPARATE PRODUCT. DOES ANYONE HAVE ANY ANSWER TO THIS QUESTION? I WANT HIGH QUALITY SOIL IN MY POTS BECAUSE I LIVE IN SOUTHERN CALIFORNIA AND PLANTS ARE EXTREMELY STRESSED BY HIGH SUMMER TEMPS. AND I DON'T WANT TO JUST START SHOVELING UNKNOWN CRAP INTO MY POTS. AT THE SAME TIME I CANNOT AFFORD TO DUMP THE POTS COMPLETELY OUT BETWEEN EVERY PLANTING AND START WITH FRESH SMALL HOME DEPOT BAGS OF CONTAINER SOIL. THANKS IF YOU HAVE ANY SUGGESTIONS OR HAVE PREVIOUSLY ADDRESSED THIS PROBLEM. REGARDS - JIM
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I'm assuming you are aware that you are running the risk of disease and fungus by reusing the soil year after year?
That said, there are a couple possibilities. One would be to add 1 part mushroom manure, $3.49 per 40 lb (H. D. and Lowes), to 3 or 4 parts of your old potting mixture. OR mix equal parts of mushroom manure and peat moss, $4.99 per 2 cubic ft. bundle, and add this mixture to your old potting mix at 1 part to 2 or 3 parts of the old mix. The measurements don't have to be exact. Keep in mind that the peat is going to retain moisture. I over did it with peat one year and killed off some potted plants that needed better drainage.
"She was not quite what you would call refined. She was not quite what you would call unrefined. She was the kind of person that keeps a parrot." -Mark Twain
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So what you are losing, except for some sand during draining, is the organic stuff as it decomposes back into CO2 & H2O. As Grave Yard Guy said, you need to mix in some compost and manure into your depleted potting soil. Small pots could be dumped into buckets for blending and homogenizing of the soil.
- Bill Coloribus gustibus non disputatum (mostly)
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