[member=2128]Womble[/member]
Hi mate!
Blueberries is generally not grafted and propagating from cuts it is the right thing to do! i.e you wont risk to 'generate' spurious unproductive plants!
For blueberries it is all about Ph and root contraints.
They like very acidic soild, which is almost impossible to achieve in soil well drained due to the general wash out and leakage! I had a similar experience, where, planting in ground as it did 'sterilise' the plant.
Next year I have returned to pot.. and it did thrive. I got a plant mate 'later flowering' and the bridgeing between seasons is perfect! This give both plants more chances! Also leave on the top some odd conifer leaves, cones for extra acidity! This works actually great! Managed to crop 3Kg from each 3 years potted plant last year! I was in a suburban place and wildlife did contribute but not massively!!
As I got new garden, previously established plants only produce 2-3 dots (From wood I believe they are 6 years +). The reason behind this is 1) age of wood. Young wood 2 year old is the best option. 2) acidy of soil 3) pollination.. they can thrive up north... I am in Scotland and although you are slightly norther then me climate is similar.
Overall dont put in polytunnel.. they dont need it and I believe it is actually worst (put tomatoes and courgettes!

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If you still get willows make baskets and sell them.. lol!