Agriculture Reference
In-Depth Information
CHAPTER THREE
Winter
Winter is a time for maintenance and planning rather than lots of sowing, plant-
ing and harvesting. All the summer crops have long since finished and most of
the outside beds will either be under green manure or lying fallow until spring.
During the coldest months of the year the growth of plants in the tunnel slows to
a crawl, turning it into a big, green, walk-in larder - and that's wonderful for
anyone who wants to know that their food is coming from a trustworthy source.
However, you definitely need to provide a helping hand because of the challenge
of lower light levels and shorter days. Heavy and extended periods of frost are
always a risk.
The polytunnel gardener has to protect all tender crops from extreme tempera-
tures, while still making sure that they get as much light as possible and are
always adequately ventilated.
This last factor is especially important and probably requires the most care and
attention on a daily basis. Ignore it at your peril, or you could find yourself dealing
with more mould, which can easily strike otherwise green and healthy-looking
plants, than at any other time of the year. On days when the outside temperature
is not forecast to rise above freezing, open the doors at both ends of the tunnel
for five minutes in the early morning to let trapped cold air flow out, and then
close them again. On warmer days do likewise, but leave at least one end of the
tunnel open until an hour before sunset.
Of course, at the same time you have to deal with pests. Many small animals no
longer hibernate during our winters as, despite the overnight frosts that we all
get from time to time, it doesn't usually get really cold for long enough to make
it necessary for them to do so. Accordingly, they may be out and about looking
for food right through the year. All of them will see your tunnel as a protected,
comparatively warm space with dinner available 24/7, so you have to be careful
when providing ventilation - or you will find that it's not only air that is being
encouraged to circulate through the tunnel.
One of the great benefits of a polytunnel over a greenhouse is the larger footprint
on which the structure stands. Being a much cheaper proposition, the average
polytunnel tends to be quite a bit bigger than the average greenhouse and covers
