Protected Plant Production

Course CodeBHT223
Fee CodeS2
Duration (approx)100 hours
QualificationStatement of Attainment

Learn to grow plants in a controlled environment such as a greenhouse; shade house; cloche or inside a building.

There are two main reasons to choose to grow a particular crop in a protected environment, such as a greenhouse:

1. Because the plant simply does not grow well enough in the open (e.g. it may be damaged by extreme conditions, or appropriate conditions might not occur in order to stimulate the crop to reach maturity (e.g. Flower buds might not form).
2. Because a protected environment will achieve greater productivity or a less risky outcome (e.g. the chances of damage to the crop are fare less, or the rate of growth is so much faster).

Sometimes, even though these benefits might be had, it might not be economically viable to grow a crop in a protected environment. For example you may grow better strawberries under cover; but in warm climates, any additional income achieved might be very small and not enough to off set the cost of providing a structure to grow them in.

Lesson Structure

There are 8 lessons in this course:

  1. Structures for Protected Cropping
  2. Describe and Evaluate the type and shape of modern growing structures.
  3. Environmental Control
  4. Cladding Materials and their Properties
  5. Irrigation and Nutrition
  6. Relationship between Production techniques and Horticultural practices
  7. Harvest and Post Harvest Technology
  8. Risk Assessment

Each lesson culminates in an assignment which is submitted to the school, marked by the school's tutors and returned to you with any relevant suggestions, comments, and if necessary, extra reading.


  • Describe and Evaluate the type and shape of modern growing structures
  • Describe and evaluate environmental controls in protected cropping
  • Explain the nature of solar radiation, transmission properties of glass and its substitutes
  • Determine the water requirements of a crop; and methods of irrigation.
  • Relate horticultural principles to the production and harvesting of a range of crops.
  • Evaluate the factors involved in marketing protected crops.
  • Evaluate the factors involved in marketing protected crops.
  • Undertake risk assessment

What You Will Do

  • Identify the main types of growing structure.
  • Relate use of structures to shape and type of construction.
  • Identify the range of environmental factors controlled within a growing structure.
  • Describe the use of the equipment used to measure and monitor these factors
  • Name and describe a range of types of environmental controls.
  • Evaluate the use of IT facilities for environmental control.
  • Describe the meaning of “daylight” and explain the role of sunlight and diffused light.
  • Relate time of year to the quantity and quality of available light.
  • Evaluate how the shape and orientation of a structure will affect light transmission.
  • Assess the effectiveness of glass and cladding alternatives for light transmission.
  • Describe the durability and insulation properties of glass and alternative materials.
  • Select and describe appropriate systems of irrigation for plants grown in situ.
  • Select and describe appropriate systems of irrigation for container grown plants.
  • Specify and evaluate systems for incorporating plant nutrients into the irrigation water.
  • Explain the effects of environmental control on a range of plants.
  • Relate the essential features necessary for successful plant establishment and development to their underlying scientific principles.
  • Describe the production of a range of crops.
  • State the optimum stage of growth for harvesting a range of crops.
  • Describe the harvesting systems for protected crops.
  • Explain how shelf life can be affected by pre and post harvesting treatment of the crop.
  • State the factors to be considered when marketing crops.
  • Evaluate alternative marketing outlets.
  • Relate packaging & presentation to marketing.
  • Assess benefits to the grower and customer, of grading a crop before marketing.
  • Determine elements of risk in the practical operations associated with protected plant production.
  • Identify safe working practices.

How Can the Growing Environment be Controlled?

Each year with new research and technology, the greenhouse system is becoming more complex. To effectively manage the interior environment within the greenhouse, consideration must be given to a range of factors including:

  • temperature
  • irrigation
  • shading -both natural and with blinds/curtains
  • light-including supplemented light if needed
  • levels of CO2
  • mist/fogging
Sophisticated monitoring and control systems such as analogue controls, thermostats and computerised environmental management equipment are often used in large set-ups to enable the grower to accomplish the monitoring process. 

Computer controlled equipment is now available to manage the greenhouse environment. The computers are capable of delivering a 15 to 25% saving in costs and reduce labour considerably. They are able to control temperature, humidity, light intensity, application of black cloth shade, light reduction as needed, ventilation fans and irrigation. Some of the advantages are:
Computer controlled environments can control the temperature to within one-tenth of a degree where manual control is at best within 2-3 degrees. They also do the job gently which puts less ‘load’ on the equipment, rather than the abrupt changes from manual operation.
It works 24 hours a day, 7 days a week. It will deliver the most cost-efficient control of your heating/ventilating system every minute of the day and night.

  • Thermostats either on-off or proportioning are inexpensive and easy to install. On-off thermostats control fans, heaters and vents as temperatures change. Proportioning thermostats provide continuous control of systems with changes in temperature.
  • Analogue controls use electronic sensors that enable the heating and cooling systems to be integrated giving greater environmental control and performance then just thermostats alone.
  • Computerised controls use microprocessors to make complex evaluations from sensors placed throughout the greenhouse
  • Computerised environmental management systems are the most sophisticated, flexible and accurate way to control the greenhouse environment. All the equipment throughout the system is tied together allowing unlimited environmental control options. The greenhouse is divided into zones each zone has an array of sensors that feed information back to the computer which then analyses and changes settings according to the environmental conditions. These systems are becoming popular with large producers.
  • Link to external weather station – sensors strategically placed within the structure and linked to external computers that are programmed to activate to establish optimal balance of growing conditions can manipulate all environmental factors. The measurements and adjustments are made to maintain growth at the fullest potential, without unnecessary expenditure of energy. The new computer control systems are manually programmed, which allows the grower to alter growing parameters to accommodate a new crop or incorporate new information.  
  • Ability of systems to record data - these new computer controlled systems, known as ‘intelligent environmental controllers’ also record data, including temperature, light intensity, carbon dioxide concentrations and humidity. The adjustments


  • Farmers and farm workers growing cut flowers, fruits, herbs, vegetables or other crops in a protected environment
  • Equipment suppliers (dealing with greenhouses, farm supplies, hydroponic equipment, etc.
  • Plant nurserymen
  • Horticultural consultants
  • Horticultural teachers
  • Research workers 


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