Understanding Grow Lights & Botany 101

Aug 20, 2021
How plants use light is critical to understanding how to grow them successfully.
Light & Photosynthesis
Through a process called photosynthesis, plants turn light into energy. The plant's leaves and stems are the light collectors which absorb the rays, and specific cells (chloroplasts in the plant's stem and leaf cells and store all the needed pigments and food) convert the light energy into sugars. These sugars move around the plant, feeding different biological functions. Photosynthesis in plants generally involves the green pigment chlorophyll and generates oxygen as a byproduct. When light reaches a chloroplast, chlorophyll absorbs the pigment inside the chloroplast and converts it into sugars to use as energy. The more areas of a plant that can absorb light, the more photosynthesis occur within the plant. It is essential to know how much light your specific crop needs to thrive. Some plants need some form of light only three to six hours a day, while others need twelve hours to produce fruit. If you were to take these two types of plants and swap their light schedules, they would look sickly and not reach their full yield potential; they would be stunted and possibly die. The wrong amount of light would result in the plants not producing the chemical energy needed through photosynthesis to survive and thrive. On the light spectrum, chlorophyll absorbs and uses more red and blue light, leaving more green light to bounce back to the human eye, resulting in most plants' green-colored appearance. 
Indoor Lighting
Often, artificial indoor lighting is insufficient or not the correct light spectrum to grow healthy plants. That is why most people position indoor plants near windows to absorb the sun's light, which helps produce photosynthesis to survive.
Grow Lights
A grow light is an artificial source of light that emits electromagnetic radiation in the visible light spectrum that simulates sunlight for photosynthesis. Some grow lights are programmed to give off specific light spectrum colors, allowing the plant to receive the best lighting to produce a healthy crop for harvest. Grow lights are a must for any indoor farming and cultivating of plants. 
Types of Grow Lights 
  • Incandescent lightscreate a lot of heat; in fact, 90% of the energy used by incandescent bulbs is turned into heat, while the remaining 10% produces 'white' light wavelengths. Incandescent lights are suitable for lighting up a room or growing low-light houseplants, such as vines, ferns, or dracaenas. They have limited utility for growing plants with higher light requirements. 
  • Fluorescent lights- fluorescent bulbs are suitable for plants with low to medium light requirements like African violets. They are also satisfactory for starting vegetables indoors before planting outside. Fluorescent bulbs use 75 percent less energy than incandescent lights. These lights typically come in long, tube-like bulbs in sizes, including T5, T8, and T12.
  • HID- High-Intensity Discharge grow lights including mercury vapor, metal halide, high-pressure sodium, and conversion bulbs. Metal halide and HPS lamps produce a color spectrum that is somewhat comparable to the sun and can be used to grow plants. The first type of HID was Mercury vapor lamps used for street lighting, but they produce a relatively poor spectrum for plant growth for indoor gardening. HID grow lights are more affordable than LED lights, and while less productive, represent an option for many indoor cannabis growers. HID lights also produce tremendous amounts of heat and consume more energy, making them less desirable in many applications.
  • LED Grow Lights LED grow lights consume 60% to 90% less energy than other lighting systems. LED grow lights can provide a full spectrum of controlled lighting that makes them the ideal choice for your growing space. Cannabis growers are using LED lights in their cannabis greenhouses because they require minimal maintenance and because most LEDs have light spectrums optimized for the entire growth cycle for cannabis. LED grow lights do not burn anything to produce light. Though LED lamps cost slightly more than traditional grow lights, their durability and efficiency make them cheaper in the long run.
  • Sulfur Plasma Grow Lights- Plasma lights are new to the market, making them one of the most expensive grow lights. They claim to have a full light spectrum, but that is still under testing. They work by using Light Emitting Plasma (LEP) bulbs, which seek to mimic the sun's spectral output. They are a solid-state light source, meaning they do not have an electrode.
Which Grow Light Is Right For You?
There are so many choices of grow lights; how does one choose? Whether you are looking to improve the plant's health in your house, a greenhouse farmer, or an indoor commercial farmer, you must consider what type of plants you want to grow. Know what lighting spectrum the plants need and considering the following subject may be necessary for your lighting purchase. Do the plants need: low light, bright light, 6 hours of artificial light, 14 hours of artificial light, do they need more red light or blue light, are you growing to produce tall plants, shorter plants with more foliage, flowers, fruit, or a harvest of high THC (the primary psychoactive compound in cannabis that has the high sensation) in cannabis. 
Creating an environment that is best for the type of plant you are growing takes planning, and grow lighting is critical. Being able to place lighting so that the plants can absorb as much light as possible without being so close to causing burning or drought is essential. Keep in mind how much heat some of them grow lights emit. 
The design of your growing space may dictate your light source choice.
What kind of space do you have for growing? Top lighting comes in many forms. There are linear, rack, compact, and many more. They can be mounted above the plants and lowered or raised depending on the growth stage of the plants. Top lighting can be mounted on the wall or side movable panels to ensure that light penetrates the entire leafy plant. 
Cost is a factor of grow lights. Consider the cost of the lights and the long-term costs of electricity. Maintenance is vital as some of the lights need to be changed often due to dead bulbs. Which lights emit heat, and how much will this affect the cost of cooling the greenhouse and using more electricity. Selecting the best grow light for the greatest harvests providing the highest profit for each situation, is the ultimate goal.