25) Plastic foil at the roof over peppers or tomatoes

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  • In this tip, a clamp is used to keep a lath with rolled up plastic foil. In june 2015, a new model of clamp has been added to this tip. More about it at C)#.


When you live in a good climate (for example the Netherlands) you can grow sweet peppers in the garden soil in the open air. In early autumn you can harvest 2 to 4 green peppers on each plant.

But you can put sweet pepper plants and tomatoe plants onder a roof of transparent corrugated plate. Tip 7 describes the roof.

At cold or rainy weather or during cold nights you better protect the plants at the sides. You can hang transparent plastic foil over the roof and remove it at warm weather.  But at windy weather the foil will hit and damage the plants or the foil will be blown away.

Next construction is better.

A)# Roof with sides of plastic foil

This is the new design roof of tip 7.  Under the roof there are three vertical laths; one at the left, one in the middle and one at the right. See photo.

Side view of the roof with sweet pepper plants.

Over the roof there are 2 “pieces” of plastic foil; one over the left half and one over the right half of the roof.  In the middle they overlap about 5 inch.

At each piece of foil, the ends of the foil are rolled up at wooden laths. The laths with foil are connected to short laths. These short laths are fixed to the 3 vertical laths of the roof.

On this photo foil has been “removed” at the right half.  This has been done by rolling up more plastic foil.

On this photo, left and right half have been opened by rolling up both pieces of foil.

On this photo foil has been rolled up until “high”.  At the left side every lath with foil is in a “clamp”. More about it further in this post.

In each lath with rolled up foil there is a screw at the right side. During rolling up, this screw turns in a small hole in a short lath.  More info and photos further in this post.


B)# End view and inside view

This photo shows the left end view. The foil is low.

Inside view under the roof.


C)# Opening clamp, taking out, putting in.

At the left side each wooden lath with foil is in a clamp. The lath can be taken out. After rolling up some foil the lath can be put back in the clamp again.

Next some photos about taking out, rolling up and putting back.


C1) “Old” Clamp

A metal “clip” keeps the lath with foil in the clamp.

The white plastic clamp is opened by pulling and rotating the metal clip.

Here the lath with foil has been removed from the clamp (and laid on a  laundry-basket for a moment).

I have turned the lath and more foil has been rolled up. Therefore the short lath with clamp must be lifted. Then the lath has been put into the clamp.  The lath is not yet fixed in the clamp.

The white plastic clamp has been closed by pulling and rotating the metal clip. Now the lath with foil has been fixed.


C2) New design of clamp

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On these photos you see the old and the new model clamp. On the left photo, the clamps are open, at the righ photo they are closed.

The new clamp has been made of an iron corner brace. At one side a short part has been sawn off. The brace and the sawn off piece has been mounted on a wooden lath.

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On these photos you see how the new clamp is used. The new clamp works as well as the old one. But the new one is easier to make.


D)# Short laths

At the roof there are 2 pieces of foil. This photo shows the overlap. The lath at the left side is  “lower” than the lath at the right side. In this way the laths and the foil will not collide or ravel.

The construction is as follows:

In a short lath there are 4 holes next to each other to fix the lath to a vertical lath. Using one of the 4 holes makes the lath with foil move more or less outwards.  See next photos.

On these photos you see:

  • In each short lath there are 4 holes next to each other.
  • The short laths have been fixed to a vertical lath of the roof using a bolt and a butterfly nut.
  • There is a bolt at the right side of a long lath. This bolt fits in a hole of a short lath. There is a nut and a butterfly nut to hold the bolt in the lath. During rollig up or down the bolt turns in the short lath.


E)# Closing lower and making storm proof

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With extra holes in the vertical laths, the short laths can be fixed at a lower position. Then 2 rows of plants fit under the foil.

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Before storm , you can fix the short laths using these iron pins.


F)# Closed ends


On this photo a shield made of 2 wooden laths and thic plastic foil.  Below a description.



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  • Thick plastic foil. For each end you need about 1 square meter. Price in Europe is €7.00 for 2 square meters.
  • Wooden laths, about 4 cm (1.6 inch) wide and 1.5 cm (0.6 inch) thick. For each side of the roof 2 laths of 45 cm (1 ft  6inch) and 2 laths of 70 cm (2 ft  3 inch).
  • Wood screws or chipboard screws..
  • 2 Big wood screws with big heads.
  • 2 Screw eyes.



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  • Lay two laths of equal length on each other. Drill small holes in both laths.
  • Use a thicker drill to make these holes bigger at 1 lath.
  • Bolt in (chipboard) screws in the lath with the biggest holes. Bolt in only about 1 cm (0.5 inch).
  • At 1 long lath with screws in, bolt in 2 screw eyes. Each screw eye about 7.5 cm (3 inch) from the end. Do not bolt in too deep.
  • At the long laths, drill 2 holes of about 8 mm (1/3 inch). Holes are about 7.5 cm (3 inch) from the ends and around 1 cm (0.5 inch) from one long side.


Attaching the top laths:

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  • Bolt 2 big wood screws in the horizontal lath above. “Hang” the “back side lath” on these 2 screws.

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  • Hold the foil on top at about the right position against the back side lath.
  • Push the “front side lath” against the foil. Bolt in the middle screw until almost tight.
  • Now the foil is hanging at 1 position. The foil can still be turned. The “front side lath”is slanting.

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  • Pull both short laths a little forward.
  • Turn the “front side lath” until it is in the same direction as the back side lath.
  • Turn the foil until it is hanging correct.
  • Bold all (3) screws in the short laths tight to hold the plastic foil between these laths.
  • Prick a screwdriver or an awl in the big holes of the frontside lath to make holes in the plastic foil.
  • Hang up the short laths with foil on the roof.


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On this photo you see how the upper short laths hang on the big screws. They can not fall off so easily.


Fastening the lower side:

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At the lower side, hold the foil between two long laths. Take care that these laths are about in the middle and horizontal.

Bold the screw eyes tight in the laths. Fix the lower side of the foil; push iron pins through the screw eyes into the garden soil.



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Cut away some plastic foil at the top sides to have it better fitting to the corrugated plate.


When desired you can put the sides (plastic flaps) underneath the plastic foil at the side of the roof. But the wind easily blows these flaps out again.

You better fix the flaps with iron pens. Description below.

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Mak a square hole in the foil. (fold up the foil, cut a half round or triangular hole, open the foil again). Push a iron pen through the hole and into the soil.


G)# Shifting

Each piece of plastic foil can be shifted over the corrugated plate. In this way you can open the front side of the roof and close the back side.

Or to correct when the foil hangs “oblique”.  Lift one long lath with foil and meanwhile carefully pull the other long lath down.


H)# Closed plastic foil or foil with small holes

I rolled foil with holes on the laths. At this foil it is easy to cut and roll it in a straight line.

When you want to use “closed foil” (no holes in it) the best way is to make a new roof  consisting of 2 long laths and foil rolled up.  Remove 2 laths with foil with holes and fix 2 laths with closed foil.

You can store “not used foil with 2 laths” in the top of the roof,  just below the corrugated plate.


I)# Broad


J)# A little skew


K)# And some more… 


L)# How to make

Needed for the roof:

  • Transparent plastic foil, closed foil or foil with holes in it. Length 6 meters (6.5 yd).  Width depends upon the length of the roof.
  • Wooden laths, about 1,5 inch wide, 5/8 inch thick.


L1) Clamp new design


  • Iron corner braces.
  • Wood screws or chipboard screws.
  • Black tap washers.

Below photos and a description.

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Saw off a piece from one leg of a corner brace. File the sharp metal burrs. Use a piece of wood, both parts of the brace, one washer and some screws to make up the clamp. Turn the screw throug the washer tight so the “iron strip” will turn heavily.

Fasten the clamp on a short lath.


L2) Clamp old design


  • One plastic cutting board, thickness about 1/4 to 1/3 inch.
  • Iron flat corner braces
  • Bolts, nuts, flat rings etcetera.

Below photos and a description.

The 4 white clamps are made out of a plastic cutting board and 4 iron flat corener braces.


L2a) Sawing plastic

Draw 4 equal rectangles on the board. Each rectangle is about 3.5 x 3.25 inch.

Saw this part out of the board using a hacksaw.

Saw the board in two halves.

Roll about 1.5 yard of plastic foil on a wooden lath. Then measure the hight and width of the lath with foil on it.

Continue sawing until you have 4 rectangular plates of plastic. Saw in each plate a slot using a hacksaw and a fret-saw.  The widest side next to the slot is about 2 inch. A slot is about 2/3 inch wide and 1 3/4 inch high.

As you can see, you need 2 or 4 plastic plates depending upon the length of the roof. By “turning” the plates you get “left-hand”and “right-hand” plates.


L2b) Bending and sawing flat corner braces.

For a left-hand clamp you bend a flat corner brace different from a right-hand clamp.  This photo shows 2 braces, bended in 2 different directions.

This photo shows again how to bend a brace. Put one leg of the corner brace horizontally in a vice bench. Pull on working gloves. Push with your hand against the “upright” leg of the brace. Push until that leg has been bended horizontally. When needed tap wth a hammer.

Next step is shortening a “not bended leg” using a hacksaw. After sawing, sharp metal sides are filed.


L2c) Mounting the clamps

For each piece of foil you need one left-handed clamp and one right-handed clamp.

Parts for a left-handed clamp:

  • Plastic plate with 4 holes (of 1/6 inch) drilled. The 2 holes on the left are used for the flat corner brace.  The 2 holes on the right are used to fix the clamp to a short wooden lath.
  • Flat corner brace, bent, sawn and filed.
  • Two bolts, about 1/6 inch diameter, length 1 inch and 0.8 inch.
  • Nuts 1/6 inch,  2 “normal nuts” and 1 nylon locking nut (the one with blue plastic top right on the photo).
  • 1 Rubber tap gasket, about 3/4 to 7/8 inch diameter and 1/6 inch thick.
  • 1 small flat iron washer, 1/6 inch hole. Diameter 1/4 to 1/3 inch. On the photo at the top right.

Put in two bolts and fasten them strongly with nuts. The shortest bolt at the top, near the slot opening.

Use a drill to enlarge the holes in the brace to have the bolts fitting in the holes.. Then put the brace over the 2 bolts.

Test: Lift the brace near the slot opening and lift it above the shortest bolt, while keeping the brace touching the nut of the longest bolt (below).

Very often this movement is impossible and you can’t get the brace above the bolt near the slot opening. If so, change the shape of the hole in the brace near the slot opening (from round to oval). Do this by drilling the hole while moving the drill machine from \ to /.

Put the rubber  tap gasket on the bolt. Then put the small flat iron washer on it.

Put the nylon locking nut on the bolt. Fasten this nut until the rubber ring is pushed in a little.  During fastening keep the bolt fixed with a screw driver when needed.

Two holes at the right side are used to fix the clamp to a short wooden lath.

A short lath is about 1 5/8 inch wide, 0.6 inch thick and between 20 and 21 inch long. In this lath there are 4 holes in a row.  Distances are about 1.5,  3,  4.5 and 6 inch from the end.

For my roof with 2 pieces of foil I need 4 short laths with clamps, 2 left-handed and 2 right-handed.


L3) Short laths (laths with a hole instead of a clamp)

Each long lath with foil has a dowel screw at one end. This screw fits in a hole of a short lath.

Such a short lath is about 1 5/8 inch wide and 0.6 inch thick. This short lath has about the same length as a short lath with a clamp fixed.  Reason: the distance between a long lath and a vertical lath of the roof must be equal for both ends of the long lath. Otherwise the lath will hang slanting.

In this lath there are also 4 holes in a row.  Distances are also about 1.5,  3,  4.5 and 6 inch from the end.

For my roof with 2 pieces of foil I need 4 short laths of this type.

At 2 out of 4 laths (without clamp) the end has been rounded off. This is near the hole for the dowel screw. The corners have been sawn off and polished with sand paper.

These rounded laths are used in the middle of the roof. There 2 pieces of foil overlap. Rounding off prevents foil from damaging.


L4) Long laths


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L5) Fixing foil to the long laths

Plastic foil is about 6.5 yard wide.  Unfold the plastic until you see the begin and end. Lay the foil on a lawn or so.

Fix the foil to one end of a long lath using a thumb pin.

At the other side of a long lath, cut the foil to measure. Pull the foil taut and fix it with a thumb pin.

Use thumb pins to fix the foil at a few “in between” positions on the lath.

Use scissors to cut the side of the foil straight.

Fix another long lath at the other end of the foil. The dowel screw must be at the same side as the other long lath.

Use thumb pins to fix the foil to the lath.

Roll up both sides of the foil as straight as possible untill they meet in the middle of the foil.


M)# Laying foil on the roof

Lay 2 laths with rolled up foil in the middle of the roof. Do this at calm weather.

Unroll the foil at one side for about 10 to 15 inch. Fix the lath in the clamp and with the dowel screw in the hole of a short lath.

Then unroll the foil at the other side and fix the lath to the clamp and the short lath.

Fix the second piece of foil.

Adjust the foil at all sides of the roof to the desired height.

N)# Storm proof

At June 8 and 9 2012 the wind was blowing very hard. The roof and the plastic foil have not been damaged. The foil was tightened by the weight of the long laths.

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6 Responses to 25) Plastic foil at the roof over peppers or tomatoes

  1. Pingback: 7) Roof over sweet peppers or tomatoes | sjefgardentips

  2. Seth says:

    Hi! I noticed your bent flat corner braces. How exactly did you bend them? Thanks in advance!

    • Hello Seth,
      Thanks for your reaction.
      This is how; Put one leg of the corner brace horizontally in a vice bench. Pull on working gloves. Push with your hand against the “upright” leg of the brace. Push until that leg has been bended horizontally. When needed tap with a hammer.

      The clamps “new design” are easier to make and just as good. I added new tekst to the tip.
      greets, Sjef

  3. Pingback: 9) Growing sweet peppers | sjefgardentips

  4. Sjef, thanks for this article. I already had a system slightly resembling yours, but this one is awesome. I will definitely install this one this year.
    Thanks for the idea and clear explications.

    • Hi Marcel,
      You’re welcome.
      I use this roof mainly for sweet peppers in my allotment garden.
      The roof with plastic foil is rather sturdy. The roof or foil never blew away.
      I used the same plastic foil for 2 summers, one after another. And it was still okay.
      Good luck.

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