Over the last few months, it has become blatantly clear that the primary reason people are purchasing LED grow lights is NOT to grow tomatoes and herbs. While I am sure there are a select few visitors that do actually grow everyday food or herbs indoors and even fewer still that inquire about outfitting a greenhouse for any number of plants, a majority of site visitors are here for one reason: using LED grow lights to grow cannabis.
Neither myself or this website condones or supports any illegal activities. Information is provided for legal medical marijuana growing operations and educational purposes in the event laws change. All readers are expected to check with local laws before growing.
With that out of the way, it is safe to say that most of this site's visitors that purchase LED grow lights are doing so with the sole purpose of growing cannabis for personal/medical use. I know this and, most importantly, LED grow light manufacturers know this as well so why do most of the published coverage areas seem out of touch with reality?
LED Grow Light Coverage
While some grow light companies flat out overstate their recommended growing area simply to dazzle the visitor into purchasing, others have not-so-sinister reasons for their claims. The former is out to make a quick buck - customers be damned - and they end up shooting the industry in the foot by perpetuating negative reviews. This is especially true of low-wattage LED panels and spotlights (LED grow panel review). The latter is trying (sometimes to the detriment of its bottom line) to keep neutral by not catering to any particular customer niche, i.e. Cannabis Growers.
Coverage area varies widely depending upon many factors:
- wattage of individual diodes
- shape of the grow light
- degree angle of the diodes
- overall wattage of the light
- intended usage
- . . . the list goes on
Of all of the reasons coverage is affected, the most important is its intended usage. You see, many manufacturers publish coverage areas based on the vegetative stage. This is a very important point. When plants are in the vegetative stage, they need less intense lighting than in the flowering stage. As cannabis growers already know, getting plants successfully through the vegetative stage with LED grow lights is pretty straight forward at this point. It gets tricky when bringing your plants through the flowering stage successfully due partly to the fact that some lights are just not up to the challenge. More importantly manufacturers are eager to show clients a huge savings in electricity (thus justifying the higher entry cost) stating a 90W LED grow light can support a gardening space of 4'x4'.
Let me be blunt here - a 90W LED grow light CAN support a 4'x4' footprint but only during the vegetative growth of plants like lettuce, herbs, and some fruits and vegetables. If that is what you are wanting to grow then you will do just fine. For those of you growing cannabis, coverage expectations need to be put in check.
Big Grow Space - Little Light, A Recipe For Disaster
A common complaint about LED grow lights among cannabis growers is that they just don't get the yield they were expecting as compared to their previous grows using HID lights. Or things might look great when growing - big leaves, tons of buds - but comes up short on dry weight due to light, airy buds instead of the thick, dense buds they may be used to.
If your buds are looking like the wispy little nug on the right, then your issue could be that you are trying to grow more than your light can handle. Trying to force that 90W LED grow light to fully flower all your plants in a 4'x4' space is never going to work.
What you need to do is reduce the coverage area - generally by 50% - of what a manufacturer states the light can handle for the common gardener growing flowers or herbs for cooking. So now you can use that 90W LED grow light in a 2'x2' space (enough for a couple decent plants or even a SOG/SCROG) and come away with thick, dense bud as you see in the picture below on the left.
LED Grow Light Coverage Area Guide
I have already stated that there are many factors that can affect the coverage area of LED grow lights, here is a rough guide to what I think are suitable grow spaces for a given wattage of light. There are many LED manufacturers and many more wattages of lights so here is a list of common sizes. All lights listed are tri-band, 5 spectrum grow lights. By keeping these guidelines in mind with your growing effort, you will find that your results will match or exceed your expectations.
|Light Wattage||Vegetative Stage Coverage||Flowering Stage Coverage|
|90 Watt||4' by 4'||2' by 2'|
|180W||5' by 5'||3' by 3'|
|350W||6' by 6'||4' by 4'|