The Plastic Greenhouse

Greenhouse Plastic

Polyethylene film or 'Poly' is a common and inexpensive covering for a wide range of plastic greenhouses.  It is particularly common among commercial growers using tunnel greenhouses due to its low cost per square foot.  

Traditionally greenhouse plastic sheeting, although inexpensive, was not very long lasting, tended to tear fairly easily and had relatively poor heat retention with an R value of 0.83 for 200micron (7.8mil) polyethylene film.

However, with the application of new manufacturing technology a higher mechanical strength has been achieved. Companies such as Ginegar in Israel have incorporated EVA (ethylene-vinyl acetate) and metallocene to increase strength and flexibility. EVA also provides transparency and thermal retention advantages. Other stabilization additives provide long-term durability to the poly plastic even under severe weather conditions.

Ginegar’s Sun-Selector line of greenhouse plastic sheeting incorporates a wide range of innovations to make it the go-to plastic for plastic greenhouses.

Light Transmission

As the graph below illustrates Ginegar achieves close to 80% light transmission in the crucial 400 – 700nm wavelengths with its poly film.  A maximum of light transmission is essential for the promotion of photosynthesis and other related growth processes in the plant.

Light Transmission 

Light Diffusion

Sun Selector™ light diffusion characteristics greatly improve photosynthesis efficiency by improving light dispersion. Especially important for self-shading, tall and trellised plants.

Light Diffusion graphic

Thermal Effect (IR)

• Sun Selector™ I.R. films

  • prevent heat radiation loss from the Greenhouse to the atmosphere.
  • maintain higher foliage temperatures and drier plants
  • reduce the incidence of frost damage
  • lead to saving in heating costs

Thermal Effect graphic

Anti Drip Action (AD)

Droplets formed on the inside surface of greenhouse films due to watercondensation can have negative consequences on the plant quality and growth, as they reduce light transmission by 15-30% and increase the incidence of certain diseases. The Anti Drip films contain special additives which eliminate individual droplets, turning them instead into a continuous thin layer of water that runs down the sides of the greenhouse roof and walls. 

Anti Drip films, when used properly, offer the following benefits:

• More light in the greenhouse

• Higher crop yield

• Earlier harvesting

• Better quality of crop, higher commercial value 

• Fewer diseases 

• Reduced need for Pesticides

Reduction of Mist Accumulation (Anti-mist)

The anti-mist additive minimizes the occurrence of fog inside the greenhouse, when covered by anti drip films.

• The Sun Selector™ film with Anti Mist additive helps to reduce leaf diseases such as phytoftora and Botrytis.

• allows maximal transmittance of light radiation in the early morning hours. Ultra Violet (UV) Radiation Absorption (Anti Virus)

Additives, which enable polyethylene to block the entry of U.V. radiation into the greenhouse, provide special properties to the plastic greenhouse cover.  

 

Reflected Radiation graphic

Sun Selector™ Anti-Virus films provide a significant reduction in the:

  • damage caused by various insect pests
  • incidence of viral diseases, transmitted to the plants by insects
  • sporulation of foliage diseases, especially Botrytis
  • use of fungicides and pesticides
  • “blackening” of the petals of Red roses.