Windbreaks play a key part in the successful deployment of tunnels.
Even when a tunnel has been constructed according to the
strongest possible specification, windbreaks may still important – reducing
problems with the management of doors and venting during the growing season and
minimising visual impact on the landscapes.
There are a few important things to remember:
Natural windbreaks take a while to establish so
Windbreaks should not completely block the wind,
otherwise air will tend to accelerate as it flows over the barrier and, like a
ocean wave, roll down on to the tunnels with considerable down-force.
Windbreaks will interfere with cold air drainage
during frost events. The lower canopy of natural windbreaks should be removed.
Haygrove chose to plant poplar windbreaks at their farm in
Gloucestershire. This species is probably the fastest growing windbreak tree
for northern Europe. Haygrove helped the trees by installing drip irrigation –
connected to the header pipe used to irrigate the berry crops being grown
beside the windbreak. The trees were planted 1m (3’) apart. A good variety is ‘Balsam
Spire’ (TT32). Trees can be started using 2m whips.
Another commonly used species has been Alder. The roots are
less invasive but they are slower growing and phytophthora can be a problem.