Hi there
The flies might not be specific to topsoil as I've had some nuisance with tiny flies that were living in coir. I use the blocks that expand on soaking and have not tried canna. When the tiny flies problem started I thought I might be plagued with them permanently but this didn't happen and most of time they are not there.
I really like the coir for a load of reasons including it is not full of bits of plastic and glass. Bagged topsoil, even from a good source, can contain all kinds of junk. The garden centres etc. expect us not to notice which we wouldn't if we were putting the topsoil in the garden.
__________________
Testudo Hermanni Hermanni (Corse) tortoises
|