Presentation on theme: "Starter – 2-13-12 From what you know, how does a greenhouse work?"— Presentation transcript:
Starter – 2-13-12 From what you know, how does a greenhouse work?
Functions of a Greenhouse Competencies 7.00-9.00
Functions of a Greenhouse The basic function of a greenhouse is to provide a protective environment for crop production. Several factors must be monitored: Temperature Moisture Pest control Nutrition Light
Temperature ranges must be conducive to crop production The cost of heat is the second highest expense of greenhouse plant production. (labor is the greatest expense) Greenhouses lose heat through the plastic, glass, etc. and additional heat has to be provided especially in winter.
Greenhouse Effect The greenhouse effect is the way greenhouses collect and store heat from the sun. Radiant energy warms the greenhouse and its contents
Controlling Temperatures There are two ways to control temperatures in a greenhouse: Thermostats Air or ventilation
Thermostats Thermostats should be at plant level for most accurate control. There are two kinds of thermostats: Aspirated thermostat-small fan blows air continuously over the temperature sensing unit to help maintain a more uniform temperature Thermistor-uses solid state electronics that enable growers to use computers to monitor the greenhouse environment
Temperature Control Equipment Heaters Fans Cooling pads Mechanical air conditioners Ventilators Shade cloths and materials Fogging and misting
Moisture must also be conducive to plant production Moisture is monitored by Watering Humidity levels
Controlling Moisture Levels Humidistat is used to control fogging or misting systems to regulate relative humidity (moisture) in the air. Heat dries moisture from the air and moisture must be added by both watering and through misting and fogging for most plants.
Moisture Control Equipment Watering system Shade cloth Foggers Mist system Humidifiers
Controlling Light Levels Photocell measures light intensity and relays signal to computer that turns on lights or activates the shade cloth to control light Timer is used to turn lights on or off at a certain time
Light Control Equipment Lights Shade cloths Shade materials Black cloth
Writing Assignment Explain to me in detail (use pictures if needed) how a greenhouse works.
Maintaining Temperature Equipment Inspect heaters Use adequate clean fuel Ensure that thermostats are working properly Inspect fans, fan motors, belts, etc. Check water levels in cooling pads and are clean Shade cloths should be attached and applied or removed depending on need
Maintaining Light Equipment Determine need for shade cloths to be attached or removed Replace light bulbs as needed Ensure that timers and photocells are working correctly
Maintaining Moisture Equipment Inspect humidistats and fogging or mist systems Ensure that water lines and faucets are not leaking Determine if there is an adequate source of high quality and clean water
General Maintenance Practices Inspect and make structural repairs Loose, torn or cut plastic covers Broken glass or fiberglass Door locks and fasteners Air leaks Damaged framework and foundation
General Maintenance Practices Inspect and make repairs for controls and equipment Heaters Fans Pumps Thermostats Humidistats Photocells Timers sprayers
General Maintenance Practices Inspect and make repairs for utilities Water Electricity Gas or fuel oil Waste and trash disposal
Chapter 19 – pg 357-358 Finish work from yesterday! Part A 1, 3, 5 Part B Part C 1-10 Get the Greenhouse Production Review Test from the front table!