Greenhouse Management

Course CodeBHT257
Fee CodeS3
Duration (approx)100 hours
QualificationStatement of Attainment

Learn About Different Types of Greenhouses and Their Management

The greenhouse is a system for environmental modification that allows plants to grow in climates and seasons that they cannot otherwise grow in. Learn about different types of greenhouses, systems and equipment, and understand their management to optimise plant growth.

 

Lesson Structure

There are 9 lessons in this course:

  1. Types of Greenhouses
    • Greenhouse Designs for Commercial Nursery Production
    • Greenhouse Construction Methods and Materials
    • What Type of Greenhouse is Appropriate for Your Nursery?
    • Siting Greenhouses
    • Greenhouse Benching
    • What Can You Grow?
    • Environmental Control in Greenhouses
    • Computerised Environmental Control
  2. Growing Systems and Equipment
    • How to Grow Plants
    • Measuring Conditions Inside a Greenhouse
    • Environmental Control Systems
    • Getting Plants to Flower Out of Season
  3. Pest and Disease Management in Greenhouses
    • How to Stop Pests and Diseases Entering the Greenhouse
    • Detecting and Controlling Pests and Diseases in the Greenhouse
    • Common Greenhouse Diseases
    • Disease Control
  4. Temperature Management
    • Temperature Control in a Greenhouse
    • Heating Systems
    • Ventilation Systems
  5. Water Management
    • Greenhouse Irrigation
    • Soil and Water
    • When to Irrigate
    • The Nursery Irrigation Program
    • Plants and Water
    • Equipment and Methods
    • Maintenance of Watering Systems
  6. Nutrition Management
    • Irrigation and Nutrition Control
    • Liquid Feed Systems
  7. Managing Light
    • Importance of Lighting in a Greenhouse
    • Artificial Lighting
    • Measuring Light
    • Controlling Light in the Greenhouse
    • Photoperiod Manipulation
    • Growth Rooms
    • Efficient Lighting Control
  8. Managing Gasses
    • Carbon Dioxide Enrichment
    • Pollutant Gases
    • Temperature Control Systems (Ventilation)
  9. Automation and Robotic Applications for Greenhouse Production
    • Automation in Vegetable nurseries

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.

Aims

  • Compare different types of greenhouses to better match the plants to be grown inside the greenhouse to be built.
  • Explain the equipment and measuring devices (manual and automated) used inside a greenhouse to help grow plants more effectively.
  • Explain options for reducing the impact of pests and diseases on plants grown inside greenhouses.
  • Detect and control the temperature within an optimal growing range for plants being grown in a greenhouse.
  • Control water in a greenhouse, including irrigation and humidity.
  • Control nutrient levels in a greenhouse at optimal levels for plant growth and health.
  • To explain how light levels can be maintained in a greenhouse for optimal plant production.
  • Explain how to best manage the air characteristics inside a greenhouse.

Inside the Greenhouse 

Although greenhouses are designed primarily to keep plants warm and make the most of available sunlight, they present a unique opportunity to control all environmental factors which influence plant growth.

Some of the things we look at in this course include:

Fogging for humidity - the advantage of a fog system is that it creates the humid environment, which is necessary to prevent the cuttings from drying out but eliminates the water droplets that sit on the leaves in mist systems. Fog droplet sizes are less than 20 micrometres, and they remain airborne long enough for evaporation to occur so that the water is held suspended in the air as a vapour, unlike the larger drops from misting systems which fall out of suspension onto leaves, etc. Humidity levels will be in the vicinity of 90-100%.
Use of water sensors - dielectric sensors measure the soil dielectric constant, an important electrical property that is highly dependent on substrate moisture content. The substrate dielectric constant can be considered as the substrate’s ability to transmit electricity and it increases with the increase of substrate water content. One advantage of this type of sensor is it gives an almost instantaneous reading.

Light intensity sensors - the light sensor is made using an LDR (light dependent resistor). The resistance of the LDR varies according to intensity of light falling on the surface. When the torch is turned on, the resistance of the LDR falls, allowing current to pass through it. The sensors are placed under the shading system at a height approximately 30 cm above the plants on each side of the greenhouse. Light measurements help optimise growth and can be used to automate supplemental light levels in greenhouses and guide positioning of lights in indoor growth facilities. 

Pest control - the integration of biorational pesticides (also known as least toxic or biopesticides) in greenhouses is often necessary in addition to cultural and biological control measures.  Insecticidal soaps (effective against pupae and nymphs and against certain plant pathogens, such as powdery mildews) and horticultural oils (neem tree  produces azadiractin, which interferes with the normal moulting process of insects and is effective against several foliage fungal pathogens) are the examples of insecticides that can be integrated into a biological control program. Beauveria bassiana is a naturally occurring fungus that attacks a wide range of pests including aphids, whiteflies, thrips, and spider mites. 

Pulse watering - this can be used to get a deeper penetration of water where water lost due to runoff is excessive. Pulse watering involves shorter irrigation periods but a greater number of irrigation periods (e.g. Instead of watering for half an hour daily, it might involve a 5 minute watering followed by a 15 minute break, then another 5 minutes of watering and another 15 minute break etc. This might repeat twice more, giving a total of 20 minutes of watering). It has been found that in many cases, pulse watering results in greater water penetration, less wastage through runoff and overall, the same result can be achieved with less use of water.

Fertigation - in greenhouse fertigation systems an automatic mixing and dispensing unit is installed which consists of three system pumps and a supplying device. The fertilisers are dissolved separately in tanks and are mixed in a specific ratio and supplied to the plants through drippers. A typical system may comprise of two tanks beneath each proportioner sealed with a lid through which the proportioner suction hose is fitted. When new solutions are mixed in the tanks, the controller must be turned off to prevent proportioners taking any unmixed solutions.

Artificial lighting - greenhouse growers can meet the requirements of plants by providing supplemental light within the useful light spectrum, and by making intensity adjustments using automated lighting. Other improvements in plant performance throughout the year from supplemental lighting include boosted weights, adjustment of colours, and better cold tolerance of plants. Several artificial light sources have various colour combinations of light. These lights may or may not meet the photosynthetic needs of a plant.

How this Course Could Help You

This course is an advanced greenhouse management course. If you already have a basic understanding of plant growth and environmental influences on plants, and you know a little about different greenhouse components, then you should be in good stead to successfully complete tis course. 

If you are new to greenhouses it will be more challenging, but it is still achievable.  Preferably you will have access to a greenhouse, or you can visit commercial greenhouses to help build your knowledge, though this is not imperative.   

The course is most suited to people working in – agriculture, horticulture, greenhouse growing, hydroponics, crop growing, vegetable production, market gardening, propagation, and plant nurseries. It may also be beneficial for those wishing to make a move into commercial crop production or small-scale crop production.    

 

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