11) Robust tunnel for early green beans

boonboon

In this tip:

  • Introduction
  • A)# Building the frame
  • B)# Putting foil on
  • C)# Using the tunnnel
  • D)# At very warm weather
  • E)# At heavy frost
  • F)# Breaking down

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Introduction

You can sow first green bean seeds on absorbing paper in April (early spring). The bean plants are planted in the garden soil under a plastic tunnel. This is to overcome frost damage during cold nights and days.

In this chapter a description of this tunnel.

The tunnel has been made of plastic tubes covered with plastic foil. The bows at both ends are fixed using an wooden beam.

Length of the tunnel is about 4 meters. Width is 1.2 meters.

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A)# Building the frame

A1) Needed

Pieces of electrical conduit pipes (pvc), each about 2.5 meters long, 2 wooden laths, 2 screw eyes, 2 metal pens.

The metal pens are made of concrete iron bars. Length is about 70 centimeter (2 ft). Each pen has been bent at 10 centimeter (4 inch) from one end using a bench vice. Put a piece of (garden) hose over it.

The conduit pipe fits in the screw eye. When needed you can change the size of the screw eye with tungs. Drill a hole in the end of the lath before putting in the eye screw.

Drill some holes in each lath. Drill them slanting. See photos below.

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A2) Building

The photos above show how to put the first bow and the last bow in the soil. The other bows are put between these two bows.

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A3) Different construction

andere-boog

andere-boog-oog

You can fix the first and the last bow using laths that are perpendicular in the garden soil. In each lath is a screw eye. The screw eye is about 50 centimeters (1 ft  8 inch) above the soil.

  • Put the wooden lath (perpendicular) in the garden soil.
  • Put the conduit pipe in the screw eye.
  • Pull the lath a few inches up.
  • Put the ends of the bow in the garden soil.
  • Push the lath in the soil again.
  • Press on the earth around the lath. To fix the lath in the soil.

This construction is more simple than the one with a slanting lath. And no metal pens needed.

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A4) Tie wraps through the bows

tunnel-stormvast

The ends of the bows can go out of the soil during storm or heavy wind. To overcome this problem you can drill 2 holes in the tube, put a tie wrap trough the holes and make a loop in the tie wrap. Put a metal pen through the loop in the soil.

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B)# Putting foil on

B1) Needed

  • Plastic foil, about 2 x 6 meter.
  • 2 plastic flower pots (about 5 inch top diameter).
  • Paving stones or bricks.
  • Spring clamps (clips).  Type of clamps, see     here   .

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B2) Foil on

  • Cut the bottom out of the 2 flower pots.
  • Lay plastic foil over the bows.
  • At each end of the tunnel:
    • lay one paving stone on the garden soil.
    • pull the short end of the foil through the bottomless flower.
    • lay the short end of the foil on the paving stone.
    • lay 2 paving stones or bricks on.

KONICA MINOLTA DIGITAL CAMERA

  • Lay heavy things like stones or bricks on the foil at the “cold side” (opposite of the sunny side) of the tunnel.

KONICA MINOLTA DIGITAL CAMERA

  • Fix the foil to the bows at the sunny side using spring clamps (clips).

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B3) Adapting clamps

klem-1

The spring clamps can be too wide over the tube. They can slip over the conduit tube. And they do not well clamp the foil.

This can be improved;

 klem-2 klem-3 klem-4

Use tongs to take remove the (red) clips. After this adaption, the clamp fits better over the tube. And the foil is fixed better.

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C)# Using the tunnel

Open the tunnel by day at sunny warm weather.

boonboon

Open the tunnel half way at warm weather as shown on this photo. The sunny side is open. The “cold polar side” (north or south) is closed.

KONICA MINOLTA DIGITAL CAMERA

Close the tunnel during cold days. And close it during the nights.

When severe wind is forecasted, put extra clamps on the tubes. See the photo above; there are two or more clamps on each bow to fix the foil.

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D)# At very warm weather

8mei2012

At a very warm day you can open the tunnel completely, as shown on this photo.

At very warm weather and a severe wind, open the tunnel completely. Put (transparent plexiglass) plates in the soil at one or both ends of the tunnel. These plates act as windscreens.

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E)# At heavy frost

Before freezing, put big plastic flower pots over the bean plants under the tunnel.

Then close the tunnel over he flower pots.

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When not freezing by day, you can do as follows (in the morning);

  • Open the tunnel,
  • Remove the flower pots,
  • Close the tunnel.

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F)# Breaking down

Remove the tunnel approximately after May 15th (mid spring). When no night-frost is forecasted anymore. The plastic foil was used for about 7 weeks in early spring. During that time the foil got little UV radiation. So the plastic foil can be used for many years before it is brittle or before it easily tears.

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