[tonydevine125]

Any suggestions about what to do with once-used grow bags ?

[Yorkie]

Stick them in the compost heap or on the soil as soil conditioner - although one main caveat is that if you grew tomatoes in them, don't put them where you plan to grow spuds or tomatoes next year (rotation).

Or something I've done with my large pots is to reuse old compost at the bottom of them and fresh compost at the top - but not if there were any diseases in the old compost, of course

[RichardA]

mine go in the polytunnel or along potato rows and get dug in. Comments about previous crops are important but if all else fail use as mulch on flower beds.
R