Types of Greenhouses Edited and adapted by: Ms. Ryan

What is a greenhouse? An area designed to grow plants An area designed to grow plants A controlled environment which allows optimum growth A controlled environment which allows optimum growth When several are joined together, they are referred to as a greenhouse range When several are joined together, they are referred to as a greenhouse range At a home they are usually attached to the house or garage At a home they are usually attached to the house or garage 6 th per. 5/11

Greenhouse Range

Three main purposes of greenhouse structure: To provide a controlled growing environment for plants whose economic value justifies the expense. To provide a controlled growing environment for plants whose economic value justifies the expense. To permit the growth of plants in regions where survival outdoors is not possible. To permit the growth of plants in regions where survival outdoors is not possible. To extend the season of growth for plants at times when they would normally go dormant. To extend the season of growth for plants at times when they would normally go dormant.

Greenhouse Location Very important – remember plant crops will be delivered at all times of the year Very important – remember plant crops will be delivered at all times of the year Keep greenhouse next to major roads to be sure that they are open through all times of the year to get goods to retailers Keep greenhouse next to major roads to be sure that they are open through all times of the year to get goods to retailers

Greenhouse Location (cont.) Several factors to be considered in establishing a greenhouse range: Several factors to be considered in establishing a greenhouse range: A. Room for expansion A. Room for expansion –1. Land larger than immediate needs should be acquired –Area should be added to this figure to accommodate service buildings, storage, and access drivers

Greenhouse Location (cont.) B. Topography B. Topography –1. Building site should be as level as possible to reduce the cost of grading –2. site should be well drained. Vast amounts of water will be in the greenhouse, so it is advisable to provide a drainage system. Try to select a site with deep, well drained loam, or sandy loam soil

Greenhouse Location (cont.) –3. Select a site with a natural wind break such as a tree line or a hill C. Land use prediction C. Land use prediction –1. Local zoning and tax laws are subject to change brought on by development pressures. Such changes have brought about the termination of many greenhouse businesses.

Greenhouse Location (cont.) D. Climate D. Climate –1. The greenhouse site should be selected with specific crops in mind Accessibility Accessibility –1. A site should be selected which has easily accessible shipping routes. –2. Select a site that isn’t long distance –3. Site location is often the deciding factor in the type of fuel used 1 st per. 5/11

Types of Greenhouses Even Span Even Span Uneven Span Uneven Span Lean-to Lean-to Quonset Quonset Gothic Arch Gothic Arch Curvilinear Curvilinear Dome Shaped Dome Shaped

Detached Greenhouses Freestanding greenhouses that may be constructed in one of several styles Freestanding greenhouses that may be constructed in one of several styles

Even Span Greenhouses A detached greenhouse style most commonly used today for single houses or for several houses connected together to form one huge structure A detached greenhouse style most commonly used today for single houses or for several houses connected together to form one huge structure –Usually have clear spans with truss supports rather than supporting columns –Without the columns the heat closures can be used to conserve energy

Even Span

Uneven Span Greenhouses One side of the roof is longer than the other side One side of the roof is longer than the other side When the longer side would face South, the sun’s heat could be used to maximum advantage When the longer side would face South, the sun’s heat could be used to maximum advantage High fuel costs are causing growers to switch back to this type of greenhouse High fuel costs are causing growers to switch back to this type of greenhouse

Uneven Span

Lean-to Greenhouses Built against other greenhouses or building Built against other greenhouses or building The roof slopes to one direction usually facing South The roof slopes to one direction usually facing South Small and may be added to other structures Small and may be added to other structures Used mostly for bulb-forcing or seed starting operations Used mostly for bulb-forcing or seed starting operations Nice to have when space is a problem Nice to have when space is a problem –Half a greenhouse 6 th per. 5/12

Lean-to

Quonset Greenhouses Used during World War II for storage sheds Used during World War II for storage sheds Inexpensive and easy to build Inexpensive and easy to build Freestanding greenhouses are often quonset type Freestanding greenhouses are often quonset type An arch shaped house An arch shaped house –Bad thing about them is the lack of height near the side walls

Quonset

Gothic arch Greenhouses Not widely used Not widely used Framework formed from laminated wooden trusses Framework formed from laminated wooden trusses Trusses made up of a bunch of wood glued together Trusses made up of a bunch of wood glued together Potted plants usually grown in this type of greenhouse Potted plants usually grown in this type of greenhouse

Gothic-arch

Curvilinear Greenhouses Used in city parks, botanical gardens, and by wealthy individuals as conservatories Used in city parks, botanical gardens, and by wealthy individuals as conservatories Was used for large conservation Was used for large conservation

Curvilinear

Dome-shaped Greenhouses Rarely used in the common flower greenhouse because it is such a small house Rarely used in the common flower greenhouse because it is such a small house Usually found at technical institutes Usually found at technical institutes

Dome-shaped

Structure Materials Galvanized steel rods make up the frame Galvanized steel rods make up the frame Frame covered with sheets of polyurethane with air space in between the two sheets to act as insulation Frame covered with sheets of polyurethane with air space in between the two sheets to act as insulation Glass and polyester can also be used Glass and polyester can also be used

Greenhouse Materials (cont.) Frame work components: Frame work components: –Slash-sill provides a base for the glass –Eave plate sits on side, post supports roof members –Gutter- collects runoff water and takes it away from the building –Drip gutter – condensation that forms on the inside of the glazing goes to the ground

Greenhouse Materials (cont.) –Slash-bars must carry weight of glazing material, snow, and wind –Bar-caps hold glazing in place; located on the exterior of the greenhouse –Purloins run the length of the greenhouse to support the slash bars –Framing materials must be strong, light, and be able to cast a shadow 1 st per. 5/13

Climate Control Heating requirement of a greenhouse depends on the types of plants that are in it Heating requirement of a greenhouse depends on the types of plants that are in it Heating must be adequate to maintain the desired temperature, day or night Heating must be adequate to maintain the desired temperature, day or night Site location is often the deciding factor in the type of fuel used. Natural gas has been cheaper than other fuels in some regions Site location is often the deciding factor in the type of fuel used. Natural gas has been cheaper than other fuels in some regions

Climate Control (cont.) 1. Heating 1. Heating –Requirement for heating a greenhouse resides in the task of adding heat at the rate of which it is lost –Heat is lost by conduction –Unit heaters are often referred to as forced air heaters 6 th per. 5/13

Fuels Many types: heating oil, gas, wood, or electric Many types: heating oil, gas, wood, or electric Heat can be distributed by forced hot air, radiant heat, hot water, or steam Heat can be distributed by forced hot air, radiant heat, hot water, or steam To keep greenhouses warm in the winter install fans to keep the heat circulating To keep greenhouses warm in the winter install fans to keep the heat circulating

Air Circulation Without the fans the hot air rises and the cold air settles around the plants Without the fans the hot air rises and the cold air settles around the plants A small fan that blows 3 feet air in a minute is equal to one quarter of the air volume A small fan that blows 3 feet air in a minute is equal to one quarter of the air volume In a small greenhouse, you should place the fans diagonally opposite in the corners In a small greenhouse, you should place the fans diagonally opposite in the corners –Develops a circular pattern of air movement

Ventilation The change from old air to new air The change from old air to new air Natural ventilation is when you have a vent in the ridge line of the roof Natural ventilation is when you have a vent in the ridge line of the roof Mechanical ventilation – an exhaust fan to move the air out one end of the greenhouse while it is sucked in the other end Mechanical ventilation – an exhaust fan to move the air out one end of the greenhouse while it is sucked in the other end

Ventilation (cont.) Needs may vary due to weather and seasons Needs may vary due to weather and seasons First you must decide how much the greenhouse will be used First you must decide how much the greenhouse will be used In summer, one half the air amount needs to be changed In summer, one half the air amount needs to be changed In winter 20-30% of air volume changes In winter 20-30% of air volume changes

Ventilation (cont.) By using LS screens you can deflect solar radiation as needed By using LS screens you can deflect solar radiation as needed With a shade retention system you can open the side walls and or roof of the structure With a shade retention system you can open the side walls and or roof of the structure

Water Systems Water is an essential need Water is an essential need Hand watering is one way Hand watering is one way Automatic system can be designed to water as needed Automatic system can be designed to water as needed Time clocks and mechanical evaporation can be used to control watering systems Time clocks and mechanical evaporation can be used to control watering systems

Detached A-frame Truss Is the most expensive to build and heat, but provides the best environment control. Is the most expensive to build and heat, but provides the best environment control. 1 st per. Reviewing 5/19

Quonset-style Greenhouse (hoop house) Requires new covering nearly every year. Requires new covering nearly every year.

Traditionally people mostly used plastic to cover greenhouses since it was cheaper than glass, but because of the recent rise in cost of all petroleum-based products, plastic and fiberglass now rival glass in initial cost.

Eight common types of greenhouse Materials Glass Fiberglass Glass Fiberglass

Soft-plastic* Shade fabric * Three different types of soft plastic: polyethylene, vinyl, polyvinyl fluoride. 6 th per. 5/18

Polycarbonate rigid panels Polycarbonate rigid panels Acrylic rigid panels Acrylic rigid panels

Hotbed: a low growing structure that uses electric cables or heating pipes to provide the warmth needed to propagate, start, or harden off plants. 1 st per. 5/18

Cold Frame- a low growing structure that uses the heat of sunlight passing through glass or plastic to provide the warmth needed to propagate, start, or harden off plants. Cold Frame- a low growing structure that uses the heat of sunlight passing through glass or plastic to provide the warmth needed to propagate, start, or harden off plants. Why is the need for supplemental heating apparent in a greenhouse? Why is the need for supplemental heating apparent in a greenhouse? –A greenhouse lacks the ability to retain sufficient heat after the sun sets.

Nearly all greenhouse systems are automated now, and many involve both primary and back-up (emergency) systems. Nearly all greenhouse systems are automated now, and many involve both primary and back-up (emergency) systems. The even distribution of air throughout the greenhouse is essential for consistent temperatures and uniform plant growth. The even distribution of air throughout the greenhouse is essential for consistent temperatures and uniform plant growth. Greenhouse air should move slightly as often to minimize mildew and other diseases of plants that proliferate under stagnant conditions Greenhouse air should move slightly as often to minimize mildew and other diseases of plants that proliferate under stagnant conditions

Ventilation System Roof & Side* Exhaust Fans Roof & Side* Exhaust Fans Retractable Roof Fan & convection tube * oldest method of ventilation

Three basic approaches taken with a greenhouse depending on time of year, and geographic location: Shading the glass to reduce light intensity. Shading the glass to reduce light intensity. Ventilating to allow cooler outside air to replace warm air inside. Ventilating to allow cooler outside air to replace warm air inside. Promoting heat exchange through water evaporation. Promoting heat exchange through water evaporation.

Two ways of providing shade in a greenhouse: Externally- spraying on a compound Externally- spraying on a compound Internally- Fabric or cloth suspended above crop to reduce light intensity. Internally- Fabric or cloth suspended above crop to reduce light intensity.

Greenhouse ventilation systems bring fresh air into the greenhouse to replace the warm internal air. Greenhouse ventilation systems bring fresh air into the greenhouse to replace the warm internal air. Especially during hot weather, ventilation alone is not enough to cool a greenhouse. Especially during hot weather, ventilation alone is not enough to cool a greenhouse. Both fan and pad cooling and fog evaporative cooling systems can reduce greenhouse temperatures from 10 degrees to 30 degrees F below the outside air. Both fan and pad cooling and fog evaporative cooling systems can reduce greenhouse temperatures from 10 degrees to 30 degrees F below the outside air. 6 th per. 5/19 1 st per. 5/20

Cooling: Fan and pad - Uses exhaust fans and continuously wet pads of excelsior (a fibrous porous material) cross fluted cellulose, aluminum fibers, or glass fibers. Cools through a re-circulating water system. Fan and pad - Uses exhaust fans and continuously wet pads of excelsior (a fibrous porous material) cross fluted cellulose, aluminum fibers, or glass fibers. Cools through a re-circulating water system. Fog evaporative- Uses a high pressure pump to create a fine mist. As the fog disperses through the greenhouse, the evaporation causes desired cooling without wetting plants. Fog evaporative- Uses a high pressure pump to create a fine mist. As the fog disperses through the greenhouse, the evaporation causes desired cooling without wetting plants.

Greenhouse and Energy Conservation Greenhouse management has shown an orientation of crop types to geographic regions. Crops needing higher temperatures are being grown more in southern states than in northern ones and vice versa. They are also constantly trying new conservation techniques.

The principle disadvantage of adding an extra layer of plastic to an existing greenhouse is the reduction of light intensity. The principle disadvantage of adding an extra layer of plastic to an existing greenhouse is the reduction of light intensity. True or False: Large amounts of heat are lost through the concrete or wooden sides of the greenhouse? True or False: Large amounts of heat are lost through the concrete or wooden sides of the greenhouse? After Dark: After Dark: –When most heat is lost in greenhouse –When fuel consumption is greatest True

Automated blanket systems have been developed for greenhouses because they can be set on timers. Automated blanket systems have been developed for greenhouses because they can be set on timers. The focus of conserving energy has caused the greenhouse industry to enter into a period of change. The focus of conserving energy has caused the greenhouse industry to enter into a period of change. The style of benches, materials used, and arrangements within the greenhouse depend upon the crop being grown. The style of benches, materials used, and arrangements within the greenhouse depend upon the crop being grown.

Three functions a greenhouse must fulfill Must drain quickly Must drain quickly Must be of a width that allows workers to reach into their center Must be of a width that allows workers to reach into their center Must maximize the crops exposure to light Must maximize the crops exposure to light

Tomatoes and lettuce require ground beds. Tomatoes and lettuce require ground beds. Raised benches are used in the production of potted crops as well as cut flowers. Raised benches are used in the production of potted crops as well as cut flowers.

Raising the bed above the ground allows air to flow more freely around the crop and permits a warmer root-zone temperature to be maintained. Raising the bed above the ground allows air to flow more freely around the crop and permits a warmer root-zone temperature to be maintained. A framework of pipe constructed above a regular bench allows for hanging baskets to be grown above another crop. A framework of pipe constructed above a regular bench allows for hanging baskets to be grown above another crop. 6 th per. 5/20

The most important quality of a bench is its capacity for rapid drainage. The most important quality of a bench is its capacity for rapid drainage. Any wood used in the construction of greenhouse benches should be preserved with some type of preservative. Any wood used in the construction of greenhouse benches should be preserved with some type of preservative. One determines the number and width of aisles within a greenhouse by finding the width of the carts needed in the aisles, and whether the crop can be worked from one side or needs to be accessible from both. One determines the number and width of aisles within a greenhouse by finding the width of the carts needed in the aisles, and whether the crop can be worked from one side or needs to be accessible from both.

Typical cross-bench arrangement

Different types of bench arrangements: Cross-bench arrangement-aisles along the sides and between the benches, is least efficient use of space for growing. Cross-bench arrangement-aisles along the sides and between the benches, is least efficient use of space for growing. Peninsular benching- features a wide central aisle to accommodate carts and other equipment. The narrow aisles between benches allow access by workers and efficient space for growing. Peninsular benching- features a wide central aisle to accommodate carts and other equipment. The narrow aisles between benches allow access by workers and efficient space for growing. Length-of-house- utilizes growing space efficiently, but workers must walk the length of the house to get to the other side of the bench. Length-of-house- utilizes growing space efficiently, but workers must walk the length of the house to get to the other side of the bench.