“You light up my life”
“You give me hope to carry on.”
“You light up my days.”
Okay, we are here to talk about grow lights and not sing along with Kenny Rogers.
To select an indoor light that is right for your plants, you need to know how plants use light and about the options you have.
Grow lights are not all created as equals. Just because you have light, your plants might love it or hate it. Why? because plants respond differently to different colors of light (spectrum), and to different light intensity (lumen).
The first grow light
In the beginning, there was light, the everlasting powerful sun. Some grow lights try to supply a light spectrum similar to that of the sun, or at least a spectrum that is more suited to the needs of the plants being cultivated. Natural sun light provide varying colors, temperatures and spectral.
Depending on the type of plant being cultivated, the stage of cultivation, and the photoperiod required by the plants, aeroponically grown plants need a specific range of light spectrum, luminous efficacy and color temperature. Not only this but also a light schedule for lightness and darkness.
Grow lights use electricity to generate light and can be used for plant growth in three different ways:
- To provide all the light a plant needs to grow.
- To supplement sunlight, especially in winter months when daylight hours are short.
- To increase the length of the “day” in order to trigger specific growth and flowering.
Pay for it now or much more later
As a general rule, inexpensive lights you can purchase tend to be the most expensive to operate and the least effective. While price is not necessarily an indicator of performance, many of the efficient grow lights require ballasts as well as specialized fixtures.
Please give me light
The distance of your light source to your plants makes a huge difference in what to use. The light radiating from your lamp that reaches the surface of your plants is inversely proportion to the square of the surface’s distance from the source. Ha? It just means that if you move the light just a little more away from your plants, the amount of light that now reaches the surface of your plants will drastically drop.
Many methods are designed to use light as efficiently as possible. Reflectors are one often used with lights to maximize light efficiency. These reflectors focus the light toward your plants. Plants or lights are moved as close together as possible so that they receive equal lighting and that all light coming from the lights falls on the plants rather than on the surrounding area.
The Right Color
Sunlight contains the complete spectrum of light, including all colors of the rainbow: red through yellow to blue and violet. Plants use the full spectrum for photosynthesis, although red and blue light seem to be most critical.
Plants need red light
Red light stimulates vegetative growth and flowering, but if a plant gets too much red light, it will become tall and spindly.
Red light, on the opposite end of the spectrum, triggers a hormone response which creates blooms.
Plants need blue light
Blue light regulates plant growth, which makes it ideal for growing foliage plants and short, stocky seedlings.
Blue light, referred to as cool light, encourages compact bushy growth.
Orange and reddish light
Grow lights producing the orange and reddish light typically produce substantial heat., However, some lights are able to produce full spectrum light without the heat.
The light spectra of different grow lights
Different stages of plant growth require different spectra. The initial vegetative stage requires a blue spectrum of light, whereas the later “flowering” stage is usually promoted with red–orange spectra.
Turn the lights out.
No matter what types of plants you are growing indoors, you must be sure to give them a rest. When it’s dark, plants respirate, which is an important part of their growth process. The balance of rest time to active growth time affects many biological processes, including the growth rate, and the setting of buds and fruit.
In addition, many plants also require both dark and light periods, an effect known as photoperiodism, to trigger flowering. Therefore, lights may be turned on or off at set times. The optimum photo/dark period ratio depends on the species and variety of plant, as some prefer long days and short nights, and others prefer the opposite or intermediate “day lengths.”
How much light? Right Intensity
The intensity of light that a plant receives is determined by the wattage of the bulb and by how close the plant is to the light source. Just as plants differ in their need for certain colors of light, they also differ in their need for light intensity. Typically, those plants that are native to tropical jungles or shady forests do not require as much light as plants that evolved in dry, sunny climates, such as the Mediterranean or southern Mexico.
Most indoor flowering houseplants are happy with the light source 10 to 12 inches away. Foliage plants, such as leafy lettuce, can be placed 36 inches away from the light source. However, closer is better. However major flowering plants vegetable plants like tomatoes, require a higher light intensity to flower and produce fruit.
Lux and lumen are photometric units, in that different wavelengths of light are weighted by the eye’s response to them. This makes them inappropriate measure of the lighting level in a horticultural lighting system. Instead, lighting levels are quantified as amount of radiation in the wavelength range from 400 to 700 nm, or photosynthetically active radiation (PAR). It can can be expressed in units of energy flux (W/m2) or photon flux (mol m-2s-1).
Plants require light levels between 100 and 800 mol
Light intensity plays a very important role in photosynthesis rates. Photosynthesis rate is the major determination in our yields. To a point, more light = more yield.
We use a light meter to measure light intensity. However, a light meter only determines how much light there is lumens (lux), not the spectrum. So we have to estimate the amount of spectrum light our plants our getting. For everything but LED grow lights, these are close to the readings to what we want at the top of the plant canopy:
15000-20000 lux – the lower end of what we want for veg growth
35000-40000 lux – what we want to try to hit this level for flowering
75000 or so lux – way too much light, you are wasting beyond this level of light intensity, saturation level
Kinds of light sources:
Fluorescent lights are available in color temperatures ranging from 2700 K to 10,000 K. Standard fluorescents are usually used for growing vegetables and herbs indoors or for starting seedlings to get a jump start on spring plantings. Fluorescents have an average usable life span of about 20,000 hours. Cool white fluorescent lights are sometimes used as grow lights. High-output fluorescent lights produce twice as much light as standard fluorescent lights. A high-output fluorescent fixture (T5) has a very thin profile, making it useful in vertically limited areas.
Compact Fluorescent lights are smaller versions of fluorescent lights used for propagation, as well as for growing larger plants. Compact fluorescents work in specially designed reflectors that direct light to plants. Compact fluorescent bulbs are also available in warm/red (2700 K), full spectrum or daylight (5000 K) and cool/blue (6500 K) versions. Usable life span for compact fluorescent grow lights is about 10,000 hours.
High-output fluorescent/high-intensity discharge hybrids combine cool operation with the penetration of high intensity discharge technology. The primary advantages to these fixtures is their blend of light colors and broad even coverage and reduced electric requirements.
They are a common choice for homeowners. Fluorescent lights are reasonably energy efficient and relatively easy to install. A typical fluorescent bulb will last approximately 20,000 hours. Fluorescent light is typically on the blue end of the spectrum. Blue light encourages bushy compact growth which makes them perfect for seed starting. Blue light is also cool to the touch making it possible to place lights within just a few inches of the seedlings.
New Full-Spectrum Fluorescent Lights. Provide the red spectrum as well to encourage blooming. Combining the lights in a fixture makes for even, all around growth. The next generation in fluorescent lighting includes the new T-5 lights. These new lights have extremely high output but are energy efficient and long lasting.
The T-5 lights triple the light output of normal fluorescent lights without increasing the wattage, less heat. Plants absorb a high percentage of T-5 lighting with their fixture. High output T-5 bulbs require a high output fixture to operate.
Bare incandescent lights generally have a red-yellowish tone and low color temperature (approx. 2700 K). They are sometimes used to highlight indoor plant groupings but not as a true plant “growing” light. Some incandescent bulbs specifically marketed as “grow lights” come with a blue filter coating which reduces the amount of red light the bulb gives off. Such “grow lights” have a brief life expectancy of about 750 hours and are energy inefficient, producing more heat than usable light.
The least expensive lights to purchase cost around $30. These incandescent lights work well for specific plants where the light is placed a minimum of 24” from the plant. These lights get extremely hot so they must be used with care. Spot grow bulbs, color corrected incandescent lights, install easily and are good for use with a specific plant or a small grouping of plants. Most spot incandescent bulbs last less than 1,000 hours. Some light fixtures come with a clip handle so you can put them exactly where they’re needed.
The newest type of grow lights use LED technology. One major advantage to the LED lights is the small size. LEDs is short for Light Emitting Diodes. They were first invented in 1927. LEDs are more efficient than any other type of artificial light. LED lights sold for growers are more powerful than ever before. Within the last few years, LED grow light systems have flooded the market for indoor gardeners.
LED grow lights offer the dual benefit of low energy-consumption and low heat- generation. LED lights weigh a fraction of other lights and are easy to configure where needed. According to LED manufacturers, LED grow lights maximize blue and red light to provide and excellent balance for plants.
LED grow lights are designed to stimulate photosynthesis by providing light in the frequencies that plants primarily use for this critical biological process. Individual LEDs may contain one of 29 known combinations of elements that emit light in different colors when excited by electrons. Grow light manufacturers emphasize blue and red LEDs in their fixtures, sometimes with other colors, which gives many LED grow lights their distinctive purplish-red color. Optimizing the light spectrum helps in two ways: it enhances photosynthesis and saves energy by not generating light in colors that plants do not use.
For vegetative growth, blue LEDs are preferred, where the light has a wavelength in the mid-400 nm (nanometer) range. For growing fruits or flowers, a greater proportion of red LEDs is considered preferable, with light very near 600-640 nm, the exact number this wavelength being more critical than for the blue LED. So hopefully by using red and blue light combination, you’ll plants happy and use less energy.
LED lights are only a few inches in diameter and are easy to mount. This make LEDs more suited to be placed close to your plants for better efficiency and waste of the light.
In conclusion – How should I light up my aeroponic plants?
For indoor crops, we have so many lighting options to choose from. Each has it pros and cons.
The easiest way to go for beginners are fluorescent lights. Purchase the most High-output fluorescent light you can afford, CFL or T-5. Use 6500K daylight bulbs. For fruiting plants, begin by adding 4100K cool white bulb. When your plants begin to flower, transition to half 6500K and half 4100K lights.
If you have the money and want to keep the electricity bill down go for LEDs. To keep the cost down get a multi-colored LED module, red, blue and white.
Stay away from high intensity discharge (HID) lights, metal halide lights and high pressure sodium lights . These lights get too hot. Not only could they be a fire hazard but these lights can heat up a small room or your home to uncomfortable levels.
Keep lights close as possible to your plants without burning them. An be sure to provide at least six hours of darkness.