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A polytunnel is a tunnel made of polyethylene
used to grow plants that require a higher temperature and/or humidity
than that which is available in the environment.
Polytunnels are mainly used in temperate regions. They are similar
in principle to greenhouses and cloches (row covers). Modern designs
allow sowing and harvesting machines to move inside the structures
so as to automate production.
Polytunnels have had a significant effect on the production of strawberries
in the United Kingdom. Other soft fruits such as raspberries and blackberries
are also cultivated in the same way.
More and more people are discovering the delights of growing fruit
and vegetables. Even a small garden can produce a surprising amount
of food - but, if you want to raise the stakes and grow better crops
all year round - you should consider buying a polytunnel.
A polytunnel is a cheap, quick way of covering a growing space. Once
you get one, you will never look back: tomatoes are easy to grow,
peppers are a pleasure and salad through the winter isn't difficult
at all.
Both crops and gardener are sheltered from the worst of the weather,
so when it's cold and wet outdoors it can be pleasantly warm to work
inside.
Start by buying in some young plants such as tomatoes, peppers, strawberries,
all-female cucumbers (easier than males as you don't need to remove
the flowers) and aubergines; then move on to growing a range of winter
salad leaves from seed. By the time one year has passed, you will
be a polytunnel enthusiast.
The freezer will be full of tomatoes, a grape vine or melons might
be on the agenda, and you will see how easy it is to grow food for
the table all year.
Top polytunnel tips for beginners
How to harness plastic in pursuit of bumper early crops that you can
grow under surprisingly cheap-and-easy-to-put-up polytunnels.
• Make a plan of what you will grow and where you will grow
it. Then keep a record of the growing year.
• Don't let the soil dry out or the temperature rise much above
86F.
• Sow little and often for a continuous supply of salad crops.
• Allow enough room between plants - if crowded they will be
more prone to disease.
• Remove any diseased foliage before the problem spreads to
other plants.
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• Use a liquid feed every seven to 10 days if plants are growing
rapidly and producing heavy crops.
• Pinch the side-shoots off tomato plants (unless they are bush
varieties).
• Always check that plants are healthy before putting them in
the polytunnel.
• Wash the polythene once a year to keep light levels up.
• Buy a roll of repair tape when you buy the polytunnel and
repair any rip as soon as you can.
Reader offer
At Telegraph Garden Shop we have a large range of polytunnels, both
net and fleece, as well as tunnel hoops, perfect for early-season
sowing.
The easy-to-use fleece tunnel is made from high-grade 30gsm polypropylene
fleece. It creates warmth and insulation while allowing water and
sunlight to filter through.
Visit gardenshop.telegraph.co.uk/polytunnel
Understanding the tunnel environment in winter means separating three
important factors which affect plant growth; sunlight, temperature
and wind chill. Wind chill is the most damaging effect outside the
tunnel, stripping heat and moisture out of plants so that they suffer
severe damage. Happily, plants inside the tunnel enjoy a sheltered
climate and so will shrug off temperatures that would kill them outside.
Temperature determines the extent to which plants can use the limited
light that they receive in winter. Because tunnels are kept warm
by the greenhouse effect, daytime temperature is directly related
to the amount of sunlight that the tunnel receives.
Sunlight is essential for plant growth. Without enough of it, plants
stop growing and concentrate on keeping their metabolism ticking
over. This means that there is a ‘no growth’ period
in winter as daylight drops off towards the winter solstice. How
long that period is depends on your latitude (and of course the
type of plant concerned); the closer to the pole, the less light
you get.
For professional growers it is feasible to provide artificial heat
and light to continue to grow through the winter. However, this
comes at a fierce environmental cost; tomatoes grown in heated British
polytunnels actually have a higher carbon footprint than tomatoes
grown in unheated tunnels in Spain and Portugal, which are then
shipped to the UK by sea and road. Although there are circumstances
when it may be justified (for example a commercial grower using
a large and highly insulated structure to bring on early seedlings
in bulk) artificial heat and light should not be viewed as a neat
‘get around’ in winter.
Instead, view your polytunnel as a walk-in store cupboard during
the no-growth period. If you have planned your winter plantings
successfully there should be produce ready to pick, and provided
you protect the less hardy plants (below) the cold temperatures
will keep the food just as it is until conditions improve. Remember,
food on the plant is still absolutely fresh – there is no
wilting or loss of nutrients unless the plant itself perishes. Much
better than the salad compartment of a fridge!
Protection:
A cold frame or fleece (floating row cover) cloche in the tunnel
will keep plants much warmer than it would outside and is often
all you need to keep the interior frost-free. If you use a fleece
cloche, make sure that the supports are tall enough to keep the
cover off the plants inside – the fabric tends to get damp
and may then freeze on cold nights, damaging any foliage it touches.
When you harvest, make sure that the protection is replaced immediately.
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Five Star Polytunnels
Cellan
Lampeter
Ceredigion
SA48 8HU
01570 421580
Contact Us |
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