When to Plant Hops

From my 'limited' research Im really struggling to find the best time to plant Hops, has any one got any advice or experiance in this?
Id like to find out the best month at least befor I start trying to hunt down somewhere to buy root stock (which is also proving a real pain!!!)

Thanks

David

Quote

Hop plants are sold as bare-root rhizomes when dormant - usually between November and April.

http://www.willingham-nurseries.co.uk/hop3.html

The pdf on planting for that site explains different planting times for rooted and unrooted (imported) varieties
http://www.willingham-nurseries.co.uk/hops/Hop%20Gardening5.pdf

Thanks for all the advice

David