What is the best LED grow light on the market for small grow tents 2021?
There is a limited range of quality small LED grow lights in the 50 watt to 150 watt range for small grow spaces of 2ft x 2ft or 60cm x 60cm.
Many of the major brands concentrate on larger lights with commercial applications and ignore the smaller grower. A lot of the small grow lights available, particularly on Amazon, are sub standard and out dated.
To help you decide on the best small LED grow light for your space we have tested and reviewed 14 of the most popular small LED grow lights on the market in 2021 from 12 different LED grow light brands. We also include reference to old technology such as fluorescent, High Pressure Sodium and ‘Blurple’ LED grow lights.
LED grow light PAR output
We show you an objective comparison of their PAR output (Photosynthetically Active Radiation, the light that plants use to grow). Each of the lights have been tested in their specified grow area and at their recommended or optimum hanging height. We have used a quantum sensor to take multiple PAR measurements across the grow area to calculate the average PAR intensity and usable PAR output of the fixture (the amount of PAR reaching the plant canopy with reflective walls).
The PAR output and light spread of all the small LED grow lights we have tested are published at the end of this article.
LED grow light efficiency
Dividing the usable PAR output of the LED grow light by its consumed power (watts drawn from the wall) we can calculate the efficiency of the fixture in PAR output per watt. To achieve a high system efficiency the grow light must use the best power supplies (LED drivers) and a high quantity of LEDs (LEDs run more efficiently when each one is run at lower current, more LEDs per watt = higher efficiency). So higher LED grow light efficiency is a very strong indicator of a high quality fixture.
Higher LED grow light efficiency also means lower heat from the fixture. Heat is a result of low efficiency where the LED drivers and lights will run hotter and increase the temperature in the grow area. This is a particular problem when growing in a small grow tent as more heat means running fans and AC at higher speeds to remove the heat resulting in more fan noise and odour leakage. Higher efficiency = more stealthy growing.
LED grow light spectrum comparison
In 2021 we now have a wide variety of LEDs to generate any PAR spectrum we like. All the grow lights tested in this comparison are truly ‘full spectrum’. This means they emit a mixture of blue, green and red light in the proportions required for good plant development from seedling, vegetative and flowering stage. This is a fantastic development in technology as there is no longer a need to compromise or be concerned about the spectrum quality of grow lights.
Grow light cost comparison
There are two main cost elements, the grow light fixture and the running cost. We have combined the two so the total cost of the grow light over three years can be compared. The cost of the fixture or the relative cost per watt is generally higher for higher efficiency led grow lights. This means the running costs will be relatively cheaper for the higher cost lights. In short you pay more up front and then less over the life of the grow light. The higher efficiency lights quickly earn back the extra spent up front and should last well beyond the three years in our calculation and save you much more than in the grow light cost chart below.
It is clear that the older technologies, ‘Blurple LEDs’, High Pressure Sodium and Fluorescents are no longer a good option due to their low efficiency and the reducing cost of quality LED grow lights.
LED grow lights with white LEDs have developed quickly over the last few years and the older technology of Blurple lights, HPS and Fluorescents are now redundant.
The Light spectrum of white LEDs (with Red diodes to increase their system efficiency) is very similar across most small LED grow lights on the market and is suitable for growing right through from seedlings to harvest.
Higher efficiency LED grow lights are more expensive to buy but save enough in electricity costs in 3 years to easily justify the additional fixture costs.
DATA for all grow lights tested and links to referenced grow light tests by Dr Coco and LED Gardener