I have a 2 year old bag of organic seed starting medium that’s outside and open with the bag folded over as well as a 5ish year old half used bag of peat in my basement that is dry. Do you think it is a bad idea for me to try and use those two for starting seeds this year?
A lot depends on your climate and conditions. If it was full of fungal hyphae or had decomposed a great deal, or been invaded by some kind of insect it might give me pause.
It might not be as perfect as new.
Though for me it's something I definitely try to buy on sale and then use for multiple years. I would use it if it were mine. Unless on examination there was something alarming about it.
However, I save my own seed and generally plenty of it. So if something went wrong I could just shrug and go get more potting media.
On some seed that's less picky I wouldn't hesitate to sow into regular potting soil or right into the native soil of my garden.
Other seed might be precious to me and I might really want to baby it. I'm babying it a bit if I use seed starting mix at all. If it was some extremely precious seed a trip to the store for a fresh bag might happen.
Western Montana gardener and botanist in zone 6a according to 2012 zone update.
Gardening on lakebed sediments with 7 inch silty clay loam topsoil, 7 inch clay accumulation layer underneath, have added sand in places.