At the back of my greenhouse I have a bag of pale brown crumbly earth labelled "Sterilised Loam". I'm not really sure what sterilised loam is. I never bought the stuff and I can't remember where it came from. It must have been there for years.

What use can it be put to, within the greenhouse? Is it any use for seedlings, pots etc? Does it matter that it's been hanging around so long?


It might matter that it's old, or it might not. Sterilized loam is never fully sterilized, or it would be inert and useless to grow anything in. Its main use is to mix with other materials to create your own recipe compost, or for using around ponds with fish or other aquatic life that might be harmed by pathogens on non sterile loam. What you don't know is whether it's had any feed added originally, and what form that might have taken. It's unlikely it had fertiliser added, but there is a risk that any nitrogen present may now have turned to nitrites - this won't be a problem on open ground, but might be in pots.

I think I'd test it by adding organic fertilizer (something like fish, blood and bone) to it and using it in pots for a few test subjects, plants you don't mind losing if it all goes wrong, preferably different varieties of plants. If the plants are fine, then it's okay to use in pots or on the soil.

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