Stuppy Greenhouse Blog

What are greenhouse curtains?

Greenhouse curtain systems are called shades, screens, and even blankets. No matter what they are called, they consist of moveable panels of fabric or plastic film used to cover and uncover the space enclosed in a greenhouse. Curtains may cover an area as small as a single bench or as large as an acre. Small systems are often moved by hand and large systems commonly by motor drive. Internal shade systems mount to the greenhouse structure below the rigid or film covering of the house. They are used for heat retention, shade (and the cooling effect of shade), and day length control or blackouts when the covering transmits lower than 1% of the incident light.

How do the curtains provide heat retention?

Any interior curtain system can be used for heat retention at night when the heating demand is greatest. Blackout systems can serve this purpose, even when day‐length control is not a consideration. The amount of heat retained and fuel saved varies according to the type of material in the curtain. Curtain systems can save energy in three ways; they trap an insulating layer of air, reduce the volume that must be heated, and when they contain aluminum strips reflect heat back into the house. A curtain system used for heat retention traps cold air between the fabric and the roof. This cold air falls into the space below when the curtain reopens in the morning. To avoid stressing the crop, it is important to uncover the curtain gradually to allow this cold air to mix with the warm air below. Alternatively, if the crop can tolerate the shade, the curtain can be left uncovered until sunlight warms the air above the system.

It may take longer but for your business it is the way to go. The way is a partnership, with a company that will work through your project with you. Some may say this takes out the competition between manufacturers in turn raising the price automatically. In reality the competition is up front, before the greenhouse that your business will rely on is the chess piece between manufacturers. The price of the greenhouse doesn’t go down in bid situations, the offering is simply reduced. Vetting companies and partnering with one you trust leads to a well thought out and designed greenhouse. In the typical greenhouse bid situation we've seen time and time again where bids come back that aren't comparable. This is due to several reasons i.e. each company has different ways of doing things, in bids price is a huge deciding factor so changes are made to the bid to reduce cost etc. This creates confusion for the buyer. The bids may be ok but deciphering the differences and coming to the conclusion of which one is right for the business is difficult.

What materials are most commonly used for glazing commercial greenhouses?

• Type 1: Thin plastic films, generally ranging from 2 to 8 mils (.002”‐.008”), normally installed using two layers with air inflation between the layers to provide added insulation. Specific types of films: ethylene vinyl acetate (EVA), polycarbonate (PC), polyester, polyethylene (PE), polyvinyl chloride (PVC), and polyvinyl fluoride.
• Type II: Rigid Plastic panels such as single layer corrugated polycarbonate and fiber glass‐reinforced plastic (FPR); multi‐wall acrylic, impact modified acrylic and poly carbonate
• Type III: Rigid Glass materials including annealed, tempered and laminated.

This article is brought to you by the NGMA

A grow light is an artificial light source designed to stimulate plant growth by emitting an electromagnetic spectrum appropriate for photosynthesis. Grow lights are used in applications where there is either no naturally occurring light, or where supplemental light is required. For example, in the winter months when the available hours of daylight may be insufficient for the desired plant growth, grow lights are used to extend the amount of time the plants receive light.

Metal Halid (MH)

• Produce an abundance of light in the blue spectrum
• This color of light promotes plant growth and is excellent for green leafy growth and keeping plants compact.
• Best type of light to be used as a primary light source (if no or little natural sunlight is available).
• The average lifespan is about 10,000 cumulative hours. The bulb will light up beyond this time but due to the gradual decline of light, it is not worth your while to wait for the bulb to finally burn out.
• If you compare their lumen (brightness) per unit of energy consumed, metal halides produce up to 125 lumens per watt compared to 39 lumens per watt with standard fluorescent lights and 18 lumens per watt for standard incandescent bulbs.

How do environmental control computers benefit horticulture?

The greenhouse environment must be accurately controlled to produce optimal conditions for crop production. In addition to controlling the humidity and temperature, environmental control computers can manage shade systems and supplemental lighting, control carbon dioxide concentration, schedule and sequence irrigation valves, and control the pH, EC, and temperature of the irrigation water. Because they integrate these functions into a single control system, environmental control computers can manage the complex instructions between these elements providing the grower with a tool to optimize production.

This article is brought to you by the NGMA

Why save energy?

• Purchased energy is a significant and ongoing expense for most greenhouse operations. There is high probability that energy prices will continue to rise.
• Most greenhouse operations have the ability to economize on fuel use.

Energy is consumed all the time, year after year. Once it is consumed, you can never get it back. Anytime you can save energy costs, you are moving money directly to your bottom line, increasing your margins and competitiveness. Energy efficient systems are usually engineered for optimum conversion, distribution and retention of heat. They can often produce better, more uniform crops, as well as being good for the environment. Even if it takes additional capital to achieve the highest level of energy saving, today’s interest rates are low, and the long life of many energy saving greenhouse system components make them sound investments.

This article is brought to you by the NGMA

How does electricity work?

Electricity moves through wires, pushed along by a force called potential. Electric potential is measured in units of volts. The voltage forcing electricity through the power wiring comes from a utility company’s generating plant. Large wires are needed to carry large currents. Electricity faces resistance to its flow through a wire, and in fact, resistance is the electrical term for the force that works against the free‐flow of electricity. Resistance is measured in units called ohms.Electricity, voltage and current all work together to form power, which is measured by watts.

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• Basic Installation – The labor cost to install a greenhouse is dependent on the equipment and the structure type.
  • CS3 vs. RB+ vs. RBS
    • Number of Columns
    • Covering Options
  • Internal vs. External Shade Systems
    • Internal is more labor intensive can will be a significant driver of labor cost
    • External is not labor intensive and can be an economical way to have shade
  • Benching
    • Benches can be labor intensive to build. Dependent on the SQFT of the project, it can be a significant driver of the labor cost 

Who is in charge of pesticide regulation?

The Environmental Protection Agency (EPA) regulates the pesticide industry under the Federal Insecticide, Fungicide and Rodenticide Act. With this law the EPA is permitted to control all aspects of pesticide use, from production through the disposal of empty containers. In many states, the Department of Agriculture is the inspecting and compliance entity for the EPA concerning pesticides.

What is the EPA Worker Protection Standard (WPS)? The Worker Protection Standard is a regulation issued by the Environmental Protection Agency. It covers pesticides used in the production of agricultural plants on farms, forests, nurseries, and greenhouses. The WPS requires you to take steps to reduce the risk of pesticide‐related illness and injury if you use such pesticides or employ workers or pesticide handlers who are exposed to such pesticides.

This article is brought to you by NGMA

If you are an agricultural pesticide user and/or an employer of agricultural workers or pesticide handlers, the WPS requires you to provide to your employees, and in some cases, to yourself and others:

• information about exposure to pesticides
• protections against exposures to pesticides
• ways to mitigate exposures to pesticides

The WPS regulations went into effect on January 1, 1995, and can be found in the EPA’s How to Comply Manual, 40CFR170.

CO2 Concentration and Plants

Photosynthesis is the process of plants using light energy to convert absorbed carbon dioxide (CO2) and water into sugars. Plants use these sugars for growth through the process of respiration.

Plants absorb CO2 through their stomatal openings located mainly on the underside of leaves. Although light, moisture, temperature and humidity levels all affect the rate of CO2 absorption, the concentration of CO2 outside the leaves is a significant influence.

The concentration of CO2 in ambient outside air commonly varies from 300 to 500 parts per million (ppm) or more by volume depending on the season, time of day and the proximity of CO2 producers such as combustion or composting, or CO2 absorbers such as plants or bodies of water. Plants growing in greenhouses, particularly “tight” double‐layer structures with a reduced air infiltration rate, can reduce CO2 levels to well below ambient levels, greatly reducing the rate of photosynthesis. Conversely, enriching the concentration of CO2 above ambient levels will significantly increase the rate of photosynthesis. In general, a drop in CO2 levels below ambient has a stronger negative effect on plant growth than the positive effects of enriching CO2 levels above ambient.

This Article is brought to you by NGMA 

Daily CO2 levels in un‐enriched greenhouse environments will climb to several hundred ppm above outdoor ambient at night due to CO2 produced by plant and microbial respiration. CO2 levels drop quite rapidly after sunrise as the crop’s photosynthetically‐driven consumption of CO2 exceeds the basic rate of respiration. In the absence of some other source, CO2 levels remain low all day limiting plant growth. At dusk, plant and microbial respiration once again begins to accumulate CO2 in the greenhouse.