Led grow lights - how to select

Hi all,

I am looking at LED grow lights and am baffled.

What are the specs that we should be looking at and how do we find honest reliable sources




Good question- I’ll be following this thread.


I bought this unit last year and had great results. It uses T5 bulbs (6500K)54w.
The total output of the system is rated as 20000 lumens ( a measure of brightness).


I tried another product that was similar but used led bulbs (32w grolux bulbs by sylvania and they were not sufficient. My plants growing under) them were stunted and didnt turn out great. I noticed that alot bulbs dont advertise how much output their bulbs produce; particularly the led ones.

I germinated my seedlings under a heat mat and tried to maintain a temperature of 70-75F. Some seeds require more or less to germinate. Generally speaking, your more tender plants will need more warmth.

The temperature at which the plants grow at is very important. For tomatoes I follwed advise, growing them between 50-60F. This grows you a plant with a thick stalk, a good root structure that will easily transplant out in cooler spring weather. Growing in warmer conditions a plant with grow faster but with tend to get leggy and not do well in the real world.


@scottfsmith has one of these lights and can vouch for them


What’s your goal, are you trying to get plants to fruit or just start plants? Do you like DIY? I made my own light out of strip lights and its worked very well for me. I’m not sure it’s more cost effective, but can be completely customized, added to, or reconfigured if needed.

I’m just using the regular white lights, but there are some manufactures that make horticulture ones with IR diodes for flowering.

Not great pictures but you can get the idea.


Very cool, Travis. Where did you find the strip lights?

I got them from digikey.com. These are Bridgelux brand, Samsung also makes some nice lights that are really efficient, but they’re a little more expensive. I like these because they’re affordable and they can be over driven to twice the power. If I remember right I can get about 9000lm/strip if I crank it up. Although your efficiency goes down. These are the older series. They have a new series out EB Gen 3 that are rated at 200 lm/watt.

Here’s some different options for sizes and color temperatures. These are about $15/strip. You’ll need to pair it with the appropriate driver which takes a little bit of research to figure out. If you want some more DIY instructions check out ledgardener.com


These look cool too, but I don’t really have a need for them.

For the fixture I used aluminum. This one is angle, but I got some 1" U channel for the other ones I made and that works a little better. heatsinkusa.com also has some 1" heatsinks that they make to whatever length you want. To attach I used double sided thermal tape. So there’s no drilling or anything.

I have 5 of these I’ve made of the past 3 years and the first ones are all still working perfectly. I don’t use them year round. Mainly they’re for starting my peppers and other random veggies in the spring.


Pretty cool! What would you estimate was the total cost for the project?

Really useful and thorough - thanks for all the facts & links. It looks tidy enough that I think my SO will approve a tiny tomato starter corner … somewhere.

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~$150 for the 4 light one probably. The driver is around $70, but if you watch on eBay you could probably find one for cheaper. For my seed starting shelves I have 3 light ones and that’s more than enough light for them. I find the higher color temp promotes better growth while the lower (3000K) promotes blooms. I had peppers blooming last winter that were only a foot tall.

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No problem. Off topic, but if you haven’t looked already check out micro dwarf tomatoes. They’re cherry types that only get around a foot tall. Perfect for indoor growing. The HLG lights linked above are supposed to be really good also.

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I’ll try to not get too off-topic, but the only reason I want to start plants indoors is to have a specific tomato (Early Cascade) that apparently isn’t being planted by greenhouses any longer. It’s an indeterminate that will grow to about six feet. https://www.ufseeds.com/product/early-cascade-tomato-seeds/ Does real well for me when I can get it.

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Okay, I misunderstood! I thought you wanted to fruit them indoors. My tomatoes did wonderful under LED lights last spring.

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I have 2 led light fixtures…one is a Ygrow that consumes about 130 watts from about a year ago and another one i bought a few months back is a parfactworks that is about 115 watts. Can’t really comment much other then they work pretty good for my houseplants. I run them about 12 hours a day…i figure the heat (they both have fans that run nonstop) is just going to heat the house this time of year. The light directly under them is very intense…like melt your eyeballs. I also have a cheap light meter i got off amzn (all of these are amazon leds).

It depends on whether you are fruiting/flowering plants, or just growing vegetative. Vegetative lights are mostly blue (400-520 nanometers), flowering lights are mostly red (630-730 nanometers). Blue light causes thick/dense foliage, red light causes fruiting/flowering and vertical/stem growth. The only advantage to white bulbs is that they contain a small amount of green light that facilitates biological processes, without wasting power on a green bulb. The amount of green light is minimal, and the blue/red spectrum of these bulbs is not optimal for plant growth. They are designed to produce white visible light for human eyes, not for photosynthesis. You are basically losing much of the efficiency of LEDs when there are a lot of white lights. You are better off saving money by buying screw-in CFL lamps made for plants than with white LEDs.

Chlorophyll a is good for flowering, chlorophyll b for vegetative growth (oversimplified). The 700-780 nanometer range improves stem growth and flowering, but is not absorbed as much as the 660-680 nanometer range. The 700+ nanometer lamps tend to generate a ton of heat, and almost always burn out if they are covered by a plastic splash guard. 660 nanometer bulbs are the major flower/fruit producers. 630 nanometer red will trigger flowering, but is mainly associated with stem/petiole growth-improves woodiness?.

A common mistake people make is mounting them too close to their plants. 3W bulbs are best 40-50 inches above the plants if they have an appropriate lens (60, 90, and 120 degree are most common, but many suppliers call the 120 degree lenses 60 degree. Primary 460/660 nanometer lamps should never be the 120 degree lens type. You reserve those for the lesser used spectrums that are still needed. For a 90 degree lens, the coverage area is twice the distance from the bulb, but is most intense directly beneath. Most of the ‘affordable’ LEDs are cobbled together with the cheapest stuff they could get their hands on, so I would not have a ton of faith in them. The claims about the long life of LEDs is mostly BS, because the cheap/noisy driver/fans will crap out on you long before the bulbs. Then you will be left with an expensive paperweight until you can source new components. Another thing to look out for are idiot salesman who think Watts are a unit of light. They pack 30x 3W lamps and 3 cooling fans into a “90W” system, and power it all with a 60W driver. This is called “getting ripped off”.

You should cover the walls of your growroom and tops of pots with Panda Film or reflective mylar to reflect light. Gloss white paints helps too, if it is laying around. In a perfect world, bulbs would not be packed together like most systems, but spread equidistant to each other, over the grow area to minimize shadows. This is why I think the long bars are a slightly better design.

There are a lot of things to consider, and I did not do a good job putting this together. I am getting tire of composing this, so I will elaborate/edit as needed. If you need a shorter answer, “you get what you pay for”, and “do your homework” will have to suffice.

This has some good info on wavelengths.

I have:

2 - blurple type lights, One is a Phlizon 1200 and The other one is a Sunraise 1000, both cover a 3x3 sqft area at 24" above the canopy

1 - double T8 fixture using ‘2’ 4000k GE led tubes, forget the Lumens atm, which I use in a 18"x48" space, roughly 12" above the canopy.

I also have a single 30w LED Hyperikon outdoor floodlight that I ended up using last year in a pinch. This was used in various ways to help get some bareroot strawberries going. It covered a nice 18"x18" or so space at about 12"-18" above the canopy.

All of my veggie starts did very well in each of the settings. All areas above had Panda Film walls and a Panda film make shift top.

All of my plants, including the strawberries were flowing before I put them in the cold.frame except the the watermelons, which were quite big despite no flowers.

None were leggy, or seemingly unhappy.

Just looked up one of them. I don’t know if this is the one you have, but it is the one you want for flowering. The only thing I don’t like is that they combine the 630 and 660 nanometer lamps together in the specs. 660 nanometer lamps are significantly more expensive and do not have the same effect as 630. Other than that small technical issue, it seems like a good system. I would also prefer 60 degree lenses on the 660 and 470 nanometer lamps to raise it up above their 18 inch recommendation. I honestly can’t explain why, but more acute lenses at a greater height have given me better results.
Good for the price.

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i have 2 viparspectra 600w leds and i love them! they’re quiet and grow nice full green plants. they have a vegetative and bloom switch. for a mid priced led they have many good reviews. i made a 5’x5’ grow room out of wood and silver tarps in my spare bedroom. with both leds running with a fan blowing it only gets to 80f in there. keeps me in fresh greens and herbs all winter. you would be surprised how much you can grow under those lights in such a small area.

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Here is the Phlizon 1200 I got on a lightning deal ~$112.

Phlizon 1200W Double Switch Series Plant LED Grow Light for Indoor Plants Greenhouse Lamp Full Spectrum Growing LED Light for Veg Bloom with Thermometer Adjustable Rope(Actual Power 250watt) https://www.amazon.com/dp/B07GBLF7Q6/ref=cm_sw_r_cp_api_i_ALI.Db9WPS12N

This is the Sunraise 1000 I got on a lightning deal and a on coupon for $91.75

1000W LED Grow Light Full Spectrum for Indoor Plants Veg and Flower SUNRAISE LED Grow Lamp with Daisy Chain Triple-Chips LED (15W LED) https://www.amazon.com/dp/B07KR2S65L/ref=cm_sw_r_cp_api_i_8NI.DbYF11HV1

At the time I purchased, I had yet to really study the physiology of plant growth in regards to light wavelengths, the ratio of each and the other attributes of lighting that impact the of how they grow and what stage such as DLI, Critical Day Length, short vs. long day etc. All that aside, now that I have a better, yet very basic understanding of the above, I’m impressed how well the plants grew under each type of light.

If I were to buy a new light today, (soon actually), I’ll be getting a light that “appears” more white, such as the Spider Farmer SF-1000 or SF-2000. I like how even the light distribution is over the given areas, assuming some sort of reflective walls are used, as should be done regardless of light chosen. I say that because as a new grow light user, it is not always clear and the PPFD can look really bad outside dead center.

As stated before by another, what we grow and or what the goal will also determine the needs.

In my case, I’m only doing veggie seedlings as as some Strawberry plant propogation so I don’t need anything crazy. That said, I’m still thinking about buying an Appogee Quantum sensor for taking readings. My theory or thinking is that while the sensor is not cheap, it could slowly pay for itself by allowing me to use and test various bulbs and setups that I have already. I realize the spectrum would still be unknown, but most of my lights are around 4000k and typically have a CRI over 90, some are 84+, and put out between 1000-1500 Lumens, so the spectrum is relatively easy to estimate.

Sorry for the long reply, I wanted to include enough info around my decisions to help those who may be going through the same situation I was in trying to learn.


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mine actually draw 265w and are also full spectrum with uv emitters. i have a cheaper 1200w king led that only draws 175w. more they draw the stronger the light is. I’ve researched this for a long time before i bought what i have. cobb leds are the best but unless you make your own fixtures, they are expensive. TheDerek makes his own and has had great results.