Is it a bad idea ro not? I used several bags this year and being rather miserly, I wonder if there is a way to save it for use again next year. I had a bit of damp-off but resolved that by adding peroxide to the water. Any suggestions?
I haven't really proved it, but it looks to me as mixing in a fair amount of fine pine bark mulch has made some of my seeds happier. It drains faster and the surface dries out faster than peat mixes do.
And fine pine bark mulch is CHEAP. I gave up on Home Deport and Lowes, where the $2.50-$3.50 bags were nasty, coarse, smelly and had big wood chips.
I went to a nice nursery and paid $7.50 for two cubic feet. I think thta is about 1/4 or 1/8th the price of most seedling mixes.
Zinnias, Lobelia, Cosmos, Snapdragon and salvia like it BETTER than Joffy-Mix. (I tend to over water, so your mileage may vary.)
I think it helps if the pine bark mulch was never stored wet, is not moldy, and smells OK. Dirty or soggy bark may hold acidic fermentation products that young roots would not like. You could flush it, but better to use clean bark. And soggy bark would tend to be less sterile. Mine was a little damp, but not stinky.
I screened mine through 1/2" hardware cloth, but the petunias might have wished I had screened theirs through a 1/4" screen. I also added a fair amount of Perlite and a little coarse sand.
If price was no object, check out fine "Orchid Bark" ... great for aeration, but shredded dollar bills might be, also!
(Since then, I found a cubic foot of #2 chicken grit for $10 - cheaper and more irregular than Perlite, and not as ugly!)
Another way to reduce the cost and increase the quality of bagged mix is to buy a bale of good peat moss, and shred it gently, then screen it gently. Keep the fibers as long as possible, so it doesn't become a fine powder. Then use that (cheap bulk peat moss) to dilute whatever fancy seedling mix you buy.
Or skip the fancy stuff altogther! Many people make their own from peat and perlite (and/or vermiculite).
Pine bark mulch (and coir) usually have some very fine fibers, and those may make peat completely unecessary.
Probably the best practice would be to plant some seeds in a cheapened mix one year, and see whether they like it better or worse. Next year, try more seeds in an even cheaper mix.
I don't ever reuse my soil. I always add it to the garden somehow but I only sow one round of seeds a year. Someone that does it for a living or germinates stuff all year will be more help for 'multi-sowings'. I have read about sterilizing soil in both the oven and microwave so you may wanna check it out online. I'm all about saving money but I want my seeds to come out as close to perfect as possible so I don't mess around with the chance of transmitting diseases through the soil for my little seedlings. It is always best to sterilize your flats or anything else you start your seeds in every year.
I may try sterilizing some just to see how bad it stinks. I had stacked the mostly emptied the flats of seedlings and set them aside do deal with later. It was amazing how many seeds still germinated and were trying to grow from around the edges. So I would have had peppers growing in the flowerbeds all over the yard. Fine, but I don't even like peppers. Yes, I always sterilize all the equipment yearly.