Greenhouse lighting. Which bulbs to choose?
Incandescent lamps
Often used as a spot lamp to illuminate a specific plant or a small group of plants. The lamp must be hung at a distance of at least 60 centimeters from the plant(s). These bulbs get hot, so they need to be hung in places where they won't interfere with work in the greenhouse.
Incandescent bulbs are used as an additional source of light for plants.
Incandescent lamps are inexpensive, but have a lifespan of less than 1,000 hours.
Fluorescent grow lamps
These lamps are ideal for germinating plants because they are traditionally at the blue end of the light spectrum, and blue light promotes growth. Since these lamps have a cooler temperature, they can be installed within 5-10 cm. from plants. As time passes and the plants grow, the lamps will have to be raised accordingly. These fluorescent lamps are quite efficient and can offer up to 20,000 hours of use.
Fluorescent grow lamps.
T-8 and T-12 bulbs refer to fluorescent lamps where T refers to the diameter of the bulb. Newer types of fluorescent lamps that emit light in the red spectrum are now available. Such lamps stimulate the flowering of plants and can be combined with blue bulbs. At the same time, they provide the entire spectrum of light needed by plants. Not so long ago, full-spectrum fluorescent lamps appeared on the market. T-5 bulbs are also available, which emit three times more light than T-8 or T-12 bulbs, while consuming the same amount of energy.
High Intensity (HID) lamps
This type of bulb is used to illuminate a large growing area. HID bulbs provide high output with light from a ballast, which allows them to be hung high above plants. These bulbs emit heat that can burn the plant's leaves if they are too close. The hanging height of an HID bulb is determined by its wattage. A reflective hood is often used with these lamps to direct light to the plants.
The HID lamp is used in the greenhouse.
There are two types of HID lights: metal halide and high pressure sodium. Metal halide lighting produces a spectrum of blue light that is very similar to natural light, so it works well as primary lighting. High pressure sodium lights use the red light spectrum and can be used as supplemental light for plant growth. The latter bulbs help plants grow straight and healthy. This prevents unwanted plant distortion and branching. High-pressure sodium bulbs last longer than metal halide bulbs, but should be replaced in accordance with manufacturers' recommendations for maximum efficiency. A bulb that has been used for a long time, but is still working, may emit less light than expected and increase energy costs.
LED grow lights
These bulbs provide a balance between blue and red light. They are small in size and weigh much less than other types of grow lights. LEDs are characterized by high light intensity. They generate almost no heat, so they are very economical in terms of energy consumption.
LED lamps are intended for lighting plants in a greenhouse.
Although they have a higher initial cost, especially compared to T-5 fluorescent lights, they can last an average of 50,000 to 100,000 hours. This is not the best and cheapest option.
Tips to keep your greenhouse energy consumption low
Ventilating and heating greenhouses can be expensive in the long run, especially if you live in colder regions. To be more efficient and economical, you can use these tips and reduce your energy consumption to a minimum.• Keep the greenhouse structure tight by reducing or completely eliminating cracks through which air can penetrate. Seal door frames and other gaps with sealant. Repair all holes in the foundation, doors, greenhouse covering and around vents. Keep the door closed.
• Insulate the greenhouse. If you are building a new greenhouse, add 2 to 5 centimeters of polyurethane or polystyrene insulation over the new foundation. Place the insulating material at a depth of 45-60 centimeters, under the entire foundation. If you already have a greenhouse with a foundation that is not insulated, repair all cracks and holes • Add a windbreak to the outside of the north greenhouse wall. Planting conifers or using a temporary fence as a windbreak can help direct the wind over the greenhouse as well.
• To prevent heat loss at night, place a thermal blanket or night curtain.
• Perform annual maintenance of heating systems (if installed).
• Use HAF fans to circulate air. Keep in mind that a tighter greenhouse retains not only heat but also moisture better. HAF fans improve greenhouse temperature and humidity levels. We discuss greenhouse ventilation in more detail in this article .
• Maximize the heated area of the greenhouse and group plants according to their temperature requirements.
• Use infrared (IR) and anti-condensation films to reduce infrared and thermal radiation losses in polyethylene-covered greenhouses.
• Use computerized control systems to increase energy efficiency.
• Use alternative heating sources.