King Plus UL Series Grow Lights – Review & Comparison (2022)

king led UL series

Are you considering a King Plus UL Series grow light? I’ll walk you through the specifications of each model, hopefully answering any questions you may have.

King LED is an LED grow light manufacturer currently offering four models of quantum board LED grow lights for use with indoor gardening. The UL Series is the newest design from King LED, and includes the UL-600, UL-1000, UL-2000, and UL-4000.

If you want a quick answer whether you can grow cannabis or other plants with these grow lights, the answer is yes, and you can purchase them here.

But I also think you should browse LED Grow Lights Depot for other high quality grow lights that you won’t find on Amazon. You never know exactly which grow light will steal your heart!

Keep reading below for the details about King Plus UL Series grow lights!

Sizes & Design:

There are four sizes available, as you can see in the images. The sizes are UL-600, UL-1000, UL-2000 and UL-4000:


The UL-600 is a small 80 watt model that’s probably only good for seedlings or a small coverage area that’s not good enough for an adult plant. I know the description says otherwise but the coverage area from 80 watts isn’t going to be large or really even very strong anywhere except the center directly underneath. I would go with the UL-1000 model or above if you want to grow a cannabis plant to harvest with these grow lights. 


(Click Here to View or Buy)

The UL-1000 consumes 110 watts of power and is good to cover a 2x2 foot area, which is sufficient for one cannabis plant.



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The UL-2000 consumes 210 watts and covers a 2x4 foot area. This size is sufficient for growing two cannabis plants.


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The UL-4000 consumes 420 watts and is the largest size and covers a 4x4 ft area. You can fit 3-4 cannabis plants in a 4x4 foot space depending on size of the plants.



The design of the King Plus UL Series is a very common design that’s been used by several different manufacturers. This is what’s known as a quantum board style design. It’s a flat board with LEDs and a driver, and nothing else.

The King Plus UL Series uses Samsung LEDs, like many of the other similar competing brands. Here’s a picture of my Spider Farmer grow light that uses the same LEDs as King Plus:


When you turn the light on you’ll be blinded. The picture doesn’t do it justice because my camera dims the image when it’s too bright.

There are a few features that distinguish this design from older model grow lights that use pink or purple looking light:

Energy Efficient

These grow lights are more energy efficient than traditional LED grow lights. That’s partially due to the fact they don’t use cooling fans. Another reason is the LEDs they used in these designs are newer versions of diodes compared to grow lights that were designed years earlier but are still for sale today.

These LEDs emit about 2.7 micromoles per Joule which is at the high end of efficiency compared to most other grow lights that typically fall between 1.5 and 2.4 uMol/Joule.

Power efficiency: 2.7 uMol/Joule;

UL 1000 consumes ~100 watts

UL 2000 consumes ~220 watts

UL 4000 consumes ~450 watts


Fanless design

Quantum board LED grow lights are designed to dissipate heat efficiently, and therefore don’t utilize cooling fans. With that said, tests of quantum board grow lights like King Plus grow lights have shown that they still generate heat.

Depending on your growing environment, you may want to still consider purchasing a space fan. During the winter months when your room is colder, the moderate heat coming from the King Plus grow light may help maintain temperatures in your grow space. But during the summer months you may choose to use a space fan if things get too warm.

Uniform Light Coverage:

sf-2000 ppfd

The uniform light coverage is perhaps the best characteristic of King Plus grow lights and other quantum board style grow lights. The image above shows how light intensity is spread a lot more evenly across the grow space.

When I tested my Spider Farmer that uses the same LEDs as these King Plus UL series grow lights, the uniformity of light is a lot better than older design LED grow lights.

This is important because you ideally want your whole canopy covered in usable light. This way the side branches have a chance of growing sizeable buds or fruits instead of only the stems under the center of the light.

Light Intensity and Coverage Area:

I’ve covered the topic of light intensity well in this article, so I won’t go into too much detail here about how I arrived at the calculations below.

But this is how the King Plus UL series grow lights stack up in terms of the light intensity they provide compared to what you need when you’re growing cannabis, fruit or vegetables.

For a moderate cannabis yield you want a light that emits ~306 uMols (PPFD) of light during an 18 hour vegetative light cycle, or ~463 uMols during a 12 hour flowering light cycle. 

If you want to get the most yield from your plants, you’ll need a stronger light emitting ~617 uMols of light during an 18 hour vegetative light cycle, or ~925 uMols during a 12 hour flowering light cycle.

The UL 1000 is a small grow light sufficient for 2x2 feet of coverage, as seen below. You can grow cannabis and other fruits or vegetables through all stages of growth with this grow light.

  King plus UL-1000 ppfd

(Click to View Details or Buy)

The UL 2000 will get you closer to the max yield levels in the center, and moderate on the edges, in addition to covering a larger 2x4 foot area compared to the UL-1000:


sf-2000 ppfd (Click to View Details or Buy)

Lastly, the UL 4000 will get you pretty close to maximum yield in a 4x4 area, definitely in a 3x3 foot area. The usable coverage area is roughly twice as large as the UL 2000:


UL-4000 ppfd

(Click to View Details or Buy)

Definitely nice performance for a grow light of this size and price. Are you looking for an industrial grow light or a stronger grow light that will flower 5x5 feet and veg 7x7 feet? The HLG 650R is more expensive, but more powerful and better for very large or industrial cannabis grows.

King Plus UL Series Hang Height Information:

Seedlings28 in.30 in.30-32 in.
Vegetative16-18 in.24 in.26-28 in.
Flowering10-12 in.16-18 in.18 in.

For more information on proper hang height, read my full article about Grow Light Hang Heights.


Light Spectrum Information:

best led grow lights

The spectrum included with King Plus UL series grow lights is exactly what you want and need for growing cannabis, or other types of plants. It consists of 3000K white, 6000K white, 660nm Red, and 760nm Infrared diodes. All together they make up a nice full spectrum white light.

Is King Plus Grow Light Dimmable?

You can not dim the King Plus UL series grow lights based on the manufacturer provided details. But thats not a huge problem because you can always increase or decrease the hang height of the grow light to increase or decrease the intensity of light on your plants.

Intensity Test & Overview Videos:

These videos are from my Spider Farmer SF-2000, but as I noted earlier, these King Plus grow lights use the same LEDs and are very similar in dimensions.

Spider Farmer LED Grow Light | PPFD PAR Intensity Test

Spider Farmer SF-2000 Quantum Board LED Grow Light Unboxing and Overview

How Do King Plus UL Series Grow Lights Compare?

mars hydro ts-3000
spider farmer sf-4000
hlg 550 eco

The main competition for King Plus UL Series grow lights are the Mars Hydro TS Series and the HLG series from Horticulture Lighting Group. There are other grow lights on the market that perform just as well, but are priced considerably higher, so I’ll discuss the two closest competitors.

What sets the King Plus grow lights apart from Mars Hydro TS Series grow lights is the brand of LEDs, as well as the slight difference in color temperature in the light spectrum.

The Mars Hydro uses unbranded LEDs and driver, as well as a slightly different color temperatures in the white spectrum, which isn’t a big deal. For that difference, the Mars Hydro TS Series grow lights are priced lower than King Plus.

King Plus UL grow lights use top shelf Samsung LM301B diodes. Both lights have received solid reviews, so it’s up to you to decide if the price difference is worth it.

King Plus grow lights are actually much closer to HLG in quality. Both grow light series use Samsung diodes. There’s a difference in light spectrum because HLG only uses one white color temperature of 3000K or 4000K where the King Plus grow lights use a mixture.

HLG is American made, so that factors into their slightly higher cost. But HLG actually offers a wider variety of models, including DIY kits that help their prices compete a lot better with similar brands. Spider Farmer only offers three pre-assembled options at the moment.

Click Here To Browse High Quality Grow Lights at LED Grow Lights Depot


Full Specifications Table:

UL 1000
UL 2000
UL 4000
” 12" x 10.5” x 2.5”
25” x 13” x 2.5”
25” x 22” x 2.5”
2x2 feet
2x4 feet
4x4 feet
Watts Consumed:
Light Intensity:
Up to 520 @ 18" height
Up to 840 @ 18" height
Up to 1320 @ 18" height
Full White + Infrared
Full White + Infrared
Full White + Infrared
LED Brand:
AC 85v to 265v
AC 85v to 265v
AC 85v to 265v
3 Years
3 Years
3 Years

Owner Comments and Warranty Info:

spider farmer grow light

The lights have solid reviews on Amazon, and they’ve generated good commentary in the forums I’ve visited. But you don’t really even need much word of mouth because the proof is in the pudding, in this case the high quality Samsung LEDs.

Regardless of whether you’re in the market for a low cost light, or a professional grade light for a larger space, Spider Farmer has a nice lineup from the affordable SF 1000 to the serious SF 4000.

The King Plus UL grow lights come with a 3 year warranty, as well as an unconditional 30 day money back guarantee. If you think Spider Farmer grow light could be right for you, check them out!


Is King Plus a good grow light?

King Plus grow lights feature modern design, efficient power consumption, and strong light intensity, making them a strong choice for indoor growing. The company has been in business for at least fifteen years.

Are King Plus grow lights a good price?

King Plus grow lights are not the cheapest grow lights, but they’re priced very competitively considering what they offer. I would say King Plus grow lights are priced fairly.

Are King Plus grow lights strong enough to grow cannabis?

The UL-1000 and UL-2000 will grow a moderate cannabis yield while the UL-4000 model will grow close to the maximum yield.

What’s the difference between King Plus grow lights and Mars Hydro grow lights?

King Plus grow lights are not dimmable, and you cannot remove the drivers and hang them outside the grow tent. You can do both of those things with Mars Hydro grow lights.

What’s the difference between King LED grow lights and HLG grow lights?

King Plus uses the same brand LEDs as HLG. King Plus grow lights are priced lower than HLG grow lights. Horticulture lighting group offers a larger selection of grow light models and DIY kits.



My name is Nick, and I'm a home grower who spends time writing about indoor growing tools and setups. My goal is for 420ExpertGuide to be a one stop shop for indoor growers to find the information they need.