poly tunnel /green house

[ROLLACOSTA]

hi guys im thinking of growing trees soon mainly from cuttings and seed..i will also be buying young whips ..do you think it will be neccesary for me to have a tunnel /green house or i think you call them in the states a hoop house..we can in the winter get frosts and prolonged bouts of rain..i think ill be growing conifers pines larch and firs also native broad leafs such as oak ,beech ,birch, thanks for any replies