In article ,
Charlie Pridham wrote:

The culprit is probably the compost, peat free and reduced peat compost
get a variety of stuff added which is normally fine but every now and
again a batch of what ever they have rotted down to add causes problems,
unfortunately you can not single out a particular brand, they can all do
this from time to time, the way we get around this on the nursery is to
A; add soil at about one third soil to two thirds compost (we just use
wicks bagged soil)
B; feed the resulting mix with a slow release fertilizer the combination
of this has meant no further problems
Some plants just seem more sensitive to peat free problems than others

That's very useful Charlie thank you. We have often wondered about the
compost ... we always use new, but it's usually "3 Large bags for £10"
kind of stuff. I'll try your recipe :-)

John