I remove half of the potting soil in my containers and toss in my garden beds, then I mix some new potting mix and a handful or so of compost together with the remaining potting mixture to amend the container soil. My plants always seem to perk up when I re-pot them this way. I think the nutrients do leach out after a year. But I've not ever changed the mixture in my rose containers, I just top them off with compost every now and again or leaf mold.
I've read an article about not disturbing the established microorganisms in all soils whether it be in the ground or in a container. I decided that if my potted roses were happy, I was not going to mess with their container potting mix. So far, that has remained true now for about 5 years. I just add compost once or twice a year on top of the potting soil.
And has anyone heard about this?
Potting Soil Contained Legionella Bacteria
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