I've grown hops in Livingston, Scotland but had limited success (mainly due to my lack of care for the poor things) but did manage to get a small crop last year (unfortunately I can't remember the variety, but I know where the appropriate piece of paper is) and they seem to be doing better each year. I know of two brewers who have had large hop crops in their gardens even further north than me (Dunfermline and Larbert) so it should be possible to grow them in Ireland.
My guess is that the latitude thing relates to commercial growing. If we only get crops of hops 2 years out of 3 in our gardens we'd probably be very happy but that would be a disaster for a commercial grower.
Apparently, the flavours in beer brewed using fresh hops are well worth the effort. The main effort seems to be to make sure that they have enough water at the appropriate time and do something to keep the pests off. I did neither so my plants have struggled during periods of drought and/or been eaten but one vine has gained sufficient strength each year to finally start cropping.
I'll definitely have a more serious attempt at hop growing when I'm established in Ireland.
Cheers, Les
