European volunteer oportunities?

My fiancee and I will be in Europe from July until mid Sept. and are hoping to find a place to volunteer at. We would like room and board in exchange for our hard work.

We both are farmers and have a lot of experience with livestock. We would like to volunteer for 4-6 weeks total, ideal with 2 different farms.
I would love to find a place that has an orchard/food forest of commercial scale, as we will be planting a 10 acre mixed fruit/nut orchard when we return to the states in the Fall.

We are flying into Germany, but want to travel around Western and possibly a bit of Eastern Europe, so we are open to the location.

If you have any questions, feel free to ask.

Thanks,
RJ

@RJ:
If you can read and write some German:
Get an account at the German WOOF-Website and search for “Obstbau”
http://www.wwoof.de/index.php?article_id=4&clang=0

For example
http://www.julia-hill-arboretum.de/
An arboretum cultivating 200 different tree and scrub species.

There are several small orcharding and viticulture farms listed. Bu you can only get the contact data when you have an account there.