Whenever its warm enough :). If they have roots they should be good to go.
Mike

Good to know!
I've seen a few cuttings planted in the ground in my area here but I was thinking they might not make it. Now, that Mike says it's ok, thanks for the info.

I stick them in the ground as soon as they are big enough that I won`t forget to water them. The sooner the better in my opinion.
Tally HO!

Torq,
I would wait until the plant is 2 years old before in ground planting if you are going to be digging them up for winter. You want to see more mature wood than green wood before doing it. if you are planting permanently i would do it at a year or so.