I noticed this response on another blog recently, and it seems that the commenter knew his stuff!
I really don't know if the notes add anything to the discussion, but it's here of anyone wants to read it!
Forgive the length of this comment, please. It's the summary of peat free compost comparisons done by a friend who is a keen organic gardener.
I bought two bags of Sylvagrow potting compost which had no date on them. I used the compost for very small seedlings and they died. I emailed Melcourt and explained the problem and they were very helpful. It seems they now put a date stamp on the bags but the bags I bought had no date stamp and must have been at least a year old. With organic composts a certain amount of slow release organic nutrients are added and if the compost is kept for a long time the nitrogen content will increase to a level which is too high for very young seedlings. I sent them a sample and they confirmed that this was the case. I took my complaint to the place where I bought the bags and sure enough there were some bags with date stamps and some without. They kindly gave me a new, date stamped bag. You live and learn. If you buy organic compost check the date and if you keep your commercial organic compost for a year don’t use it for seedlings. It is, of course, fine for larger plants or older seedlings
