Hello,

i would be getting a new poly tunnel very soon,

any suggestion ?

any sugestions on design (Height, lenght ,width )

any suggestions on direction( east-west,north=south )
advantages /disadvantages

electrical/wiring any special care?

How to take precautions for stronge winds?

yellowish & greenish poly is availabe in this area

any difference in it? advantages & disvantages for this two types?

ManyThanks,
Indulkar Shailendra
India(presently in Egypt)

wrote in message
om...
Hello,

i would be getting a new poly tunnel very soon,

any suggestion ?

any sugestions on design (Height, lenght ,width )

any suggestions on direction( east-west,north=south )
advantages /disadvantages

electrical/wiring any special care?

How to take precautions for stronge winds?

yellowish & greenish poly is availabe in this area

any difference in it? advantages & disvantages for this two types?

ManyThanks,
Indulkar Shailendra
India(presently in Egypt)



Whereabouts in India are you proposing to erect this tunnel ?
Could you not consult nearer home !!
Pete www.thecanalshop.com

In article ,
writes
Hello,

i would be getting a new poly tunnel very soon,

any suggestion ?

any sugestions on design (Height, lenght ,width )

any suggestions on direction( east-west,north=south )
advantages /disadvantages

electrical/wiring any special care?

How to take precautions for stronge winds?

yellowish & greenish poly is availabe in this area

any difference in it? advantages & disvantages for this two types?

ManyThanks,
Indulkar Shailendra
India(presently in Egypt)

We have recently purchased a replacement cover for our 30ft. x 16 ft.
Polytunnel from Northern Polytunnels in Lancashire UK. Northern
Polytunnels are part of the LBS group but they also operate separately.
They sent us an excellent advisory catalogue called Garden Structures
which contains a wide range of kits, materials and accessories for
structures from cloches to aircraft hangars.

Polytunnel covers need to be of ultraviolet inhibiting [UVI/EVA]
polythene of which three grades are offered. We chose Politherm Plus in
720g with anti fogging and high light transmission properties.

E-mail:

Tel: 01282 873120
--
Alan & Joan Gould - North Lincs.

In article ,
writes
Hello,

i would be getting a new poly tunnel very soon,

any suggestion ?

any sugestions on design (Height, lenght ,width )

any suggestions on direction( east-west,north=south )
advantages /disadvantages

electrical/wiring any special care?

How to take precautions for stronge winds?

yellowish & greenish poly is availabe in this area

any difference in it? advantages & disvantages for this two types?

ManyThanks,
Indulkar Shailendra
India(presently in Egypt)

We have recently purchased a replacement cover for our 30ft. x 16 ft.
Polytunnel from Northern Polytunnels in Lancashire UK. Northern
Polytunnels are part of the LBS group but they also operate separately.
They sent us an excellent advisory catalogue called Garden Structures
which contains a wide range of kits, materials and accessories for
structures from cloches to aircraft hangars.

Polytunnel covers need to be of ultraviolet inhibiting [UVI/EVA]
polythene of which three grades are offered. We chose Politherm Plus in
720g with anti fogging and high light transmission properties.

E-mail:

Tel: 01282 873120

--
Alan & Joan Gould - North Lincs.

"Alan Gould" wrote in message
...

[snip]

Polytunnel covers need to be of ultraviolet inhibiting [UVI/EVA]
polythene of which three grades are offered. We chose Politherm Plus
in
720g with anti fogging and high light transmission properties.

Why do polythene tunnel covers need to block UV radiation?
Surely the same plants, growing in the open thrive the full dose of UV
radiation?

Franz

Franz Heymann wrote:
"Alan Gould" wrote in message
...

[snip]

Polytunnel covers need to be of ultraviolet inhibiting [UVI/EVA]
polythene of which three grades are offered. We chose Politherm
Plus
in 720g with anti fogging and high light transmission properties.

Why do polythene tunnel covers need to block UV radiation?
Surely the same plants, growing in the open thrive the full dose of
UV
radiation?

Isn't it to protect the material, not the plants?

Mike.

wrote in message
om...
Hello,

i would be getting a new poly tunnel very soon,

any suggestion ?

any sugestions on design (Height, lenght ,width )

any suggestions on direction( east-west,north=south )
advantages /disadvantages

electrical/wiring any special care?

How to take precautions for stronge winds?

yellowish & greenish poly is availabe in this area

any difference in it? advantages & disvantages for this two types?

Why would you need to grow under a polytunnel in India?

On Fri, 19 Nov 2004 06:52:55 +0000 (UTC), "Franz Heymann"
wrote:


Why do polythene tunnel covers need to block UV radiation?
Surely the same plants, growing in the open thrive the full dose of UV
radiation?

Franz

It's not to stop transmission of UV, just to prevent UV from degrading
the plastic. You've seen what happens to non UVI polythene left in the
sun - it degrades to the point that you can crumble it in your hands.
The plastic made for tunnels has a life of several years (in the UK)
depending on quality, wind exposure and on being installed tightly so
it doesn't flap around and destroy itself.

=================================================

Rod

Weed my email address to reply.
http://website.lineone.net/~rodcraddock/index.html

In article , Franz Heymann
writes
Why do polythene tunnel covers need to block UV radiation?
Surely the same plants, growing in the open thrive the full dose of UV
radiation?

I think you may have a point there. I suggest that you advise the
suppliers of poly-tunnel covers that they have it all wrong and tell
them what material they should be marketing.
--
Alan & Joan Gould - North Lincs.

"Mike Lyle" wrote in message
...
Franz Heymann wrote:
"Alan Gould" wrote in message
...

[snip]

Polytunnel covers need to be of ultraviolet inhibiting [UVI/EVA]
polythene of which three grades are offered. We chose Politherm
Plus
in 720g with anti fogging and high light transmission properties.

Why do polythene tunnel covers need to block UV radiation?
Surely the same plants, growing in the open thrive the full dose
of
UV
radiation?

Isn't it to protect the material, not the plants?

Of course. But that is not what the OP said.

Franz

Polythene is seriously degraded by UV rays. The UV inhinitiors extend
the life of your polythene. And you will get a longer life out of thr
polythene.

It has nothing to do with plants at all.



On Fri, 19 Nov 2004 18:22:58 +0000, Alan Gould
wrote:

In article , Franz Heymann
writes
Why do polythene tunnel covers need to block UV radiation?
Surely the same plants, growing in the open thrive the full dose of UV
radiation?

I think you may have a point there. I suggest that you advise the
suppliers of poly-tunnel covers that they have it all wrong and tell
them what material they should be marketing.

"derryl" wrote in message
...

Polythene is seriously degraded by UV rays. The UV inhinitiors
extend
the life of your polythene. And you will get a longer life out of
thr
polythene.

It has nothing to do with plants at all.



On Fri, 19 Nov 2004 18:22:58 +0000, Alan Gould
wrote:

In article , Franz Heymann
writes
Why do polythene tunnel covers need to block UV radiation?
Surely the same plants, growing in the open thrive the full dose
of UV
radiation?

I think you may have a point there. I suggest that you advise the
suppliers of poly-tunnel covers that they have it all wrong and
tell
them what material they should be marketing.

I do indeed have a point which you clearly have not appreciated. The
desirable polythene is *not*used because it blocks UV, as you
originally implied. All polythene always block UV light. The
desirability of the UVI/EVA polythenes lies in the fact that they are
reasonably protected against UV damage to themselves, as numerous
posters have now pointed out.

Franz

In article , Franz Heymann notfranz.h
writes

I do indeed have a point which you clearly have not appreciated. The
desirable polythene is *not*used because it blocks UV, as you
originally implied. All polythene always block UV light. The
desirability of the UVI/EVA polythenes lies in the fact that they are
reasonably protected against UV damage to themselves, as numerous
posters have now pointed out.

So the material is correct for the purpose, rather than as you
suggested. The plants receive reduced ultraviolet light compared with
outdoor ones, but then that is also the case in a glazed greenhouse,
whether horticultural or window glass is used. Polycarbonate sheeting,
sometimes double glazed, is now being used for conservatories etc., does
anyone know what light transmission that has?

Suppliers of UVI/EVA polythene sheeting suggest a five year life span in
polytunnel use. Quite often the sheet will need replacing earlier than
that due to structural damage, but we find that by the time a sheet has
been in place for more than two or three years, it is becoming opaque.
It also collects airborne dust, bird droppings, algae etc, which we
clean off, but we cannot do anything about the opacity. In fact, growth
and health of plants in the polytunnel does not seem to be affected by
this extra light barrier, but we prefer to change the sheet before the
five years of it has become badly fogged.
--
Alan & Joan Gould - North Lincs.

Franz Heymann wrote or quoted:
On Fri, 19 Nov 2004 18:22:58 +0000, Alan Gould wrote:
In article , Franz Heymann wrote:

Why do polythene tunnel covers need to block UV radiation?
Surely the same plants, growing in the open thrive the full dose
of UV radiation?

I think you may have a point there. I suggest that you advise the
suppliers of poly-tunnel covers that they have it all wrong and
tell them what material they should be marketing.

I do indeed have a point which you clearly have not appreciated. The
desirable polythene is *not*used because it blocks UV, as you
originally implied. [...]

What Alan wrote seems to have been:

``Polytunnel covers need to be of ultraviolet inhibiting [UVI/EVA]
polythene of which three grades are offered. We chose Politherm Plus in
720g with anti fogging and high light transmission properties.''

I can't see any problem with that.
--
__________
|im |yler http://timtyler.org/ Remove lock to reply.

"Alan Gould" wrote in message
...
In article , Franz Heymann
notfranz.h
writes

I do indeed have a point which you clearly have not appreciated.
The
desirable polythene is *not*used because it blocks UV, as you
originally implied. All polythene always block UV light. The
desirability of the UVI/EVA polythenes lies in the fact that they
are
reasonably protected against UV damage to themselves, as numerous
posters have now pointed out.

So the material is correct for the purpose, rather than as you
suggested.

I never said otherwise. I pulled your leg because you misstated the
situation. Reread carefully what you said in your first post on this
yopic.

The plants receive reduced ultraviolet light compared with
outdoor ones, but then that is also the case in a glazed greenhouse,
whether horticultural or window glass is used. Polycarbonate
sheeting,
sometimes double glazed, is now being used for conservatories etc.,
does
anyone know what light transmission that has?

Polycarbonate also does not transmit much beyond the blue end of the
spectrum.
Fused quartz is one of the very few industrially used solids whose
transmission curve keeps up well into the UV wavelength region.

Suppliers of UVI/EVA polythene sheeting suggest a five year life
span in
polytunnel use. Quite often the sheet will need replacing earlier
than
that due to structural damage, but we find that by the time a sheet
has
been in place for more than two or three years, it is becoming
opaque.
It also collects airborne dust, bird droppings, algae etc, which we
clean off, but we cannot do anything about the opacity. In fact,
growth
and health of plants in the polytunnel does not seem to be affected
by
this extra light barrier, but we prefer to change the sheet before
the
five years of it has become badly fogged.

The opacity is in this case to a large extent *not* due to an
increased absorption
of light, but due to increased scattering of light. This means that
the light which does get through has simply lost information about
the shapes of objects on the far side.

Franz