Introduction
LED (light emitting diode) lights have become increasingly popular in recent years as an energy efficient and long lasting lighting solution. Many home gardeners and indoor farmers are now exploring using LEDs as grow lights for plants and vegetables. But can LEDs provide everything that plants need to grow successfully?
The benefits of using LED grow lights
There are several potential advantages to using LED grow lights:
- Energy efficiency – LEDs convert electricity into light very efficiently, with little energy wasted as heat. This makes them much more energy efficient than traditional incandescent or fluorescent grow lights.
- Long lifespan – LEDs can last up to 50,000 hours or more. This is much longer than other types of grow light bulbs which need replacing frequently.
- Compact size – LEDs are small and lightweight. This allows growers to set up efficient grow light arrays, even in tight spaces.
- Directional light – The light from LEDs is directional, allowing for more control over where the light ends up. Reflectors and lenses can focus the light on the plant canopy.
- Variable light spectrum – By adjusting the mix of colored LEDs, grow lights can provide different light spectrums optimized for the vegetative or flowering growth stages.
- Low heat output – LEDs produce very little radiant heat. This enables lights to be positioned closer to plants without risk of scorching or drying out the leaves.
- Durable – With no fragile filaments or glass bulbs, LEDs are much more resistant to vibrations and breakage.
These features make LED grow lights an appealing option for indoor gardening. The ability to produce intense light optimized for plant growth while using far less electricity gives LED grow lights the potential to revolutionize hydroponics and controlled environment agriculture.
Potential drawbacks of LED grow lights
However, there are some potential disadvantages of using LED grow lights to consider:
- Upfront cost – The initial investment in LED grow lights is higher than other types of grow light, although the cost should be recouped over time due to their efficiency and long operational lifespan.
- Light distribution – LEDs produce directional light, so even coverage over an entire plant or grow area requires careful positioning of multiple LEDs.
- Light intensity – While LEDs are efficient, high power LEDs may be needed to produce enough intensity to fully replace sunlight in some situations, adding to the cost.
- Heat management – LED lights produce heat that needs dissipating to avoid high temperatures. Proper heat sinking is required.
- Spectrum balance – The optimal blend of light wavelengths must be provided to support all stages of plant growth. This requires LEDs with different color wavelengths.
- Unknown longevity – LED technology is still advancing rapidly. The actual usable lifespan under grow light conditions is still under investigation.
These limitations need to be taken into account when designing an LED grow light setup. With careful selection of LEDs and proper fixture design, these potential disadvantages can be minimized.
Light spectrum considerations
One of the key factors that determines the suitability of LED grow lights is the light spectrum they emit. Plants require different wavelengths of light at different growth stages.
Chlorophyll absorption spectrum
Chlorophyll is the primary pigment used by plants to absorb light energy for photosynthesis. The chlorophyll absorption spectrum has two main peaks, one in the blue light region at around 450 nm and one in the red light region at around 660 nm. These are the most efficient wavelengths for photosynthesis.
| Wavelength | Color |
|---|---|
| 450 nm | Blue |
| 660 nm | Red |
Therefore, LED grow lights tailored for vegetative growth should emphasize blue and red wavelengths. However, chlorophyll on its own is not sufficient to power all plant growth.
Accessory pigments
Plants also use accessory pigments such as carotenoids and anthocyanins to harness light energy. These accessory pigments absorb strongly in the green, orange, and yellow regions of the visible light spectrum. Providing some light in these wavelengths can improve plant growth and health.
| Accessory pigment | Absorption peak |
|---|---|
| Carotenoids | 450-520 nm (blue-green) |
| Anthocyanins | 500-600 nm (green-orange) |
Therefore, LED grow lights designed for vegetative growth stages should include green and yellow wavelengths in addition to blue and red.
Photomorphogenesis
Plants also use light signals to trigger important developmental processes like germination, flowering and fruiting. These processes are influenced by specific wavelengths through the process of photomorphogenesis:
| Plant process | Wavelength |
|---|---|
| Germination | 660 nm (red) |
| Flowering | 400-500 nm (blue) |
| Fruit/seed development | 700-750 nm (far red) |
LED grow lights can be tailored to provide key photomorphogenesis wavelengths during specific growth phases. For example, emphasizing far red light during the flowering and fruiting stages.
Summary of plant light absorption
To summarize, an ideal LED grow light spectrum for general vegetative growth contains:
- High levels of blue (400-500 nm) and red (600-700 nm) light to power photosynthesis through chlorophyll absorption.
- Additional green, yellow and orange wavelengths (500-600 nm) to activate accessory pigments.
- Small amounts of far red light (700-750 nm) to regulate plant development.
The specific ratio of these wavelengths can be tailored to the growth stage. Flowering and fruiting stages benefit from more far red light, while vegetative growth requires more blue and red.
Types of LED grow lights
There are a few key varieties of LED grow lights available:
Full spectrum white LED
These LED fixtures produce a broad spectrum of light designed to mimic natural sunlight or daylight. They emit a mix of wavelengths across the visible light range from 400-700 nm. While less tailored than other LED options, full spectrum white LEDs can still offer good general purpose grow light for most growth stages.
Blurple LED
Blurple LEDs produce a combination of blue and red light, resulting in the distinctive pinkish-purple color. They target the peak absorption wavelengths of chlorophyll at blue 450 nm and red 660 nm. Blurple LEDs are optimized for photosynthesis during the vegetative growth phase.
Multi-color spectrum LED
These LED grow lights offer control over multiple color channels. The LEDs are grouped into clusters emitting different wavelengths, for example blue, red, far red, and white. By adjusting the relative intensity of each color channel, the light can be customized to specific plant needs.
Tunable spectrum LED
Tunable spectrum LED fixtures contain an array of different colored LEDs covering a wide range of wavelengths. The relative intensity of each group of color LEDs can be digitally controlled to produce a very specific light output optimized for each growth phase. For example, increasing far red output to induce flowering. This allows complete customization of the LED light spectrum.
Choosing the right color spectrum
Selecting the variety of LED grow light with the best color spectrum for your needs depends on several factors:
Growth stage
Different plant growth stages have varied light requirements:
- Seedlings need lower intensity light focused on the blue and red chlorophyll absorption peaks.
- Vegetative growth benefits from more blue and red light to fuel rapid plant growth.
- Flowering and fruiting requires more far red light to trigger blooming and seed/fruit production.
Select LEDs tailored to the growth phase of your plants. For example, blurple LEDs for seedlings and vegetative growth, or a tunable spectrum LED to transition from vegetative to flowering.
Crop selection
Some plant varieties have specific light spectrum needs. For example, lettuce and leafy greens grow best under LEDs with enhanced green and yellow light. Know the optimal light requirements for the crops you intend to cultivate.
Grow space size
The size and layout of your grow space impacts light requirements. For larger spaces, high power broad spectrum white LEDs can provide adequate intensity for total light replacement. A small grow tent may need more focused blurple or tunable LEDs.
Budget
Tunable spectrum LED fixtures provide the most customization but at a higher cost. Fixed spectrum LED grow lights like blurple are a more budget-friendly option. Compare lighting costs to the value of your anticipated harvest.
Energy efficiency
Full spectrum white LEDs convert electricity into photosynthetically useful plant light less efficiently than customized LED spectra. Prioritize energy efficiency for larger grow spaces with higher electrical costs.
By taking into account these factors, you can select the LED grow light system with the spectral output that best matches your horticultural setup and goals.
Other LED grow light considerations
In addition to the light spectrum, there are a few other features of LED grow lights to evaluate:
Wattage and coverage
More watts and higher power LEDs produce greater light intensity. Make sure the LED grow light has adequate power and footprint to cover your grow space and plants. Insufficient intensity results in weaker, stretched growth.
Light distribution
Look for grow lights engineered to distribute light evenly. Reflectors, lenses, and arrangement of LED clusters all impact coverage. even light distribution promotes consistent growth across the entire plant canopy.
Cooling and heat management
Proper heat sinking and fans must be incorporated into the LED light fixture design. Evaluate reviews to ensure selected grow lights don’t run excessively hot for your space.
Safety certification
Make sure LED grow light electrical systems carry standard safety certifications to avoid risks of fires or electrical problems when operating at high power. Reputable grow light manufacturers will indicate certified safety testing.
Warranty
LED grow lights are long term investments, so look for at least a 3 year manufacturers warranty. 5 years or more of coverage is ideal, as it reflects confidence in the LED lifespan and product quality.
Cost effectiveness
Compare LED grow lights based on the cost per square foot of growing area covered, or cost per intensity of photosynthetic light produced (measured in micromoles). More expensive LEDs may pay for themselves over time via enhanced yields and energy savings.
Conclusion
LED technology offers indoor gardeners unmatched ability to provide customized, energy efficient supplemental light tailored to any plant’s specific needs. While upfront costs are higher, the long lifespan and efficiency of LED grow lights along with their potential to optimize plant development and yields make them one of the most promising and rapidly developing grow light technologies available. Carefully evaluate LED color specs, intensity, coverage, cooling, and quality of construction to choose the best LED grow light option for your gardening setup and goals. Properly implemented, LED grow lights can take indoor and controlled environment cultivation to new levels of productivity and sustainability.
