Home and professional growers have used a different variety of light sources that distribute their light differently. And while some are a big fan of HPS lamps, others swear by LEDs. Horticraft Holland thinks LED has many benefits over other types of light sources, which we will discuss in another article. In this article we want you to meet the different types of lamps growers use.
High Intensity Discharge (HID) lamps
High Pressure Sodium
HPS lights are the most common type of supplemental grow light for professional greenhouse growers. HPS lights emit a mix of yellow, orange, and red light, making HPS lamps great for the flowering phase, but not so great for the vegetative phase of your plants. Metal Halide (MH) lights are used with HPS, since these emit more blue light and are thus useful for the vegetative phase of the plant. HPS lamps produce a lot of light, but also a lot of heat. The bulbs can reach very high temperatures (as high as 450ºC or 842ºF) and lights should not be placed too close to the crops or anything flammable. HPS bulbs have a lifespan of about 10.000 hours and should be replaced every 12 months.
MH lights are mostly used during the vegetative phase because MH lamps put out light in the blue and green range of the spectrum. That’s why you’ll see MH and HPS used in combination, MH will be used during the vegetative stage and when it’s time to flower, the MH bulbs will be replaced by HPS bulbs. Since MH lights are best for vegetative stage, they are good for growing lettuce and spinach. MH bulbs are filled with a gas mixture of mercury and metal halides (compounds between metals and halogens). To grow with MH bulbs, you will also need a ballast and a reflector. Finding the right ballast is important, since it can underpower or overpower the MH bulb. Overpowering the bulb can lead to the bulb exploding. MH lights tend to become very hot and can lead to serious burns of your canopy, but also anything flammable. MH bulbs have a lifespan of around 6.000-15.000 hours and should be replaced every 6-10 months.
Ceramic Metal Halide
CMH lights have a balanced output, since they have a mix of blue, orange and red light. This makes CMH lights more PAR efficient than MH or HPS lights. Though, HPS still have a better red light output than CMH and are better for the flowering stage. The Color Rendering Index (CRI) of CMH bulbs is higher than MH and HPS bulbs, making your plants appear more realistic with CMH lights. This makes it easier to inspect your plants for diseases and pests, but also for their general well-being and growth. CMH lights have a higher initial cost than both MH and HPS lights, although they will prove to be cheaper in the long run. CMH lights put out a lot of heat and should be handled with caution. CMH bulbs have a lifespan of around 20.000-24.000 hours and should be replaced every 2-3 years.
Compact Fluorescent Lightning
CFLs are cheap and suitable for small grow areas or a single plant. They can be found in most hardware stores. These types of light are especially great for beginners. The “soft white” and “daylight” color temperature bulbs are best for gardening. The daylight bulbs are good for the vegetative stage, while the soft white are better for the flowering phase. CFL bulbs put out less heat than HPS bulbs and can be placed closer to the plant, making them well suited for seedlings and young plants or any other kind of low-key indoor gardening. However, the light does not penetrate deep into the canopy, making them less suitable for bigger plants and full grow areas, and as a consequent giving you lower yields. Since the light from CFL bulbs is mostly pointed away from the plant, using a reflector can be useful to direct all light to your crops. CFL bulbs have a lifespan of around 8.000-15.000 hours and should be replaced every 6-10 months.
Light Emitting Diodes
LEDs use a low amount of energy and put out little heat. LED lights are made up of many small diodes and each of these can be customized to put out a specific color wavelength. This means that LEDs can be customized to a full spectrum, making them ideal for every stage of the plant life cycle. LEDs have a better penetration than CFL bulbs and their light can be directed better. LEDs produce a lot less heat (usually less than 65ºC or 149ºF) and direct a lot less infra-red radiation towards your plants. Although LED grow lights are the most expensive option, they are far cheaper in the long run, since you will need less climate control, pay less for energy consumption, get higher yields and their lifespan is significantly longer. LEDs have a lifespan of around 50.000 hours and should be replaced every 5 years.