7 Best Grow Lights For Autoflowering – How Many watts

(Last Updated On: August 15, 2021)

Do you want to know what are the best grow lights for autoflowering? Autoflowers and led grow lights are the best combinations. You don’t believe me? Well, then believe the expert marijuana growers. Mr. Canucks, one of the best auto breeders. He  advised that you should use full spectrum LED lights for maximum production.

Both are the most advanced version of their respective field and complement each other perfectly. Auntoflower grown under led grow lights gives the best yield, perfect growth structure, lively green leaves, and fresh flowers.

Now you might naturally wonder how to grow these cannabis plants in my grow space, What would be the best led grow lights for autoflowering, do they even need bulbs for their growth, should I use LED, HPS, or HID  lights, how long should I keep it on, what should be the light spectrum, should I do anything else to increase the plants efficiency and more importantly how many watts light should I buy. 

Hold your horses and sit tight because I will answer them all.

So let me tell you all about how many LED watts per autoflower you would need, some initial details and most importantly some of the best LED grow lights options for you to choose from. So let’s get started.

What is Autoflower?

First and foremost, if you are just starting your journey as a cannabis breeder or thinking about becoming one, you would need the safest and most hassle free option. That’s where autoflower comes in.

The present day cannabis producers have a buffet of choices. Now more than ever there are many varieties of plants In the market just to meet the growers’ needs.  Numerous producers are fancied and taken aback by the new and improved variant of marijuana. i.e autoflower.

In around the late 1990s a cannabis breeder and researcher Joint Doctor accidentally came across the original strain of autoflower cannabis. He named the strain Lowryder.

But funny enough this sort of cannabis plant wasn’t that popular back when it came to the market. It was less efficient than others for its low THC level. But growers tinkered with it for a while and finally came up with the best marijuana to grow indoors.

It has high CBD or THC levels now and takes about 10 weeks to fully grow ( for dwarf it takes only 100 days). 

So this cannabis plant is now popular among growers for three reasons

  • It can withstand harsh weather
  • It grows really fast and
  • When the plants have matured it automatically flowers regardless of the light source

Where did the Autoflower come from?

I already mentioned that a person named  Joint Doctor was the creator of an autoflower cannabis strain. How did he discover it?  Well, no one ever got hands on the full spec yet. However, we did get the information on our hand that the auto-flowering trait derived from a particular strain of Cannabis ruderalis.

These types of cannabis plants are the strains of marijuana that mostly grow in Central and Eastern Europe. And since Ruderails emerged from a colder, less hospitable environment than other mainstream marijuana like Indica and Sativa, it evolved as an auto-flowering plant so that it can quickly grow and produce a quality harvest.

This first strain of autoflower (Ruderalis) grows abundantly in ditches and elsewhere in its indigenous environment. It is a type of cannabis, after all. But on the downside, it doesn’t contain much THC like the others. So buyers mostly rejected these autoflowers at first.

Joint Doctor then continued his research and mixed and matched many generations of Indica, Sativa, and ruderalis to get that perfect hybrid.  And finally, he did! The output of his hard work is the current autoflowers- Ideal marijuana for both indoor and indoor grow space. 

Today, there are roughly three hundred varieties of auto-flowering cannabis that are just as THC efficient as their associate marijuana.

Why Choose Autoflower?

Now, you might wonder what makes it better than regular Sativa or Indica plants. Well, these variants are “photoperiod”. This means like the Starks in Winterfell they need a constant reminder that winter is coming.

You will need to invest in grow lights, create specific light schedules and change the light spectrum from time to time in your tent. Extra Cost, Extra Work. Since you are growing the marijuana indoors, you need to set your room in a way that it can mimic the change of nature for the plants to grow and harvest.

However, the freshly originated strains of autoflowers have proven to be a savior of all this hustle and bustle. Let me tell you why-

  •  Autoflowers can create excellent medicine. . Most breeders satisfyingly concluded that some newest variants have 25 percent THC. The developed autoflower marijuana also has a rich amount of  CBD content.
  • The growth rate is pretty high. In about 13 weeks they give a good harvest. Some plants mature even before that. Par plant yield is pretty good too.
  • You can keep the structure of the plants small to accommodate your grow space. The amount of quality of the harvest will still be the same. 
  • The marijuana ruderalis spreads flowers 2–3 weeks after germination [the maturing of the plant from seed after a while of staying dormant.]
  • You can save a lot of money since they don’t need a distinct vegetative and flowering environment.
  • Easy seed re-production. Per plant can produce hundreds of seeds.  Some even grow up to be 1 foot (30.5 cm) tall. So they can easily be produced in any compact grow area and have a short blooming period. 
  • Photoperiod dependent cannabis plants need a lot of attention and a certain amount of heat to grow.  But since autos have a short lifespan they can easily endure cold weather.

When to Put Autoflower under Grow Light

Now on to the first dilemma! You keep one thing in mind, as an indoor gardener you always need to invest in grow lights.  The amount and spectrum may differ from plant to plant but you will always need to invest in some grow light.

The question is why? Most plants require light to trigger photosynthesis. It turns energy into a food source, And naturally, your autoflowers need food for growth. And your plants are planted indoors; they are not getting sufficient light sources to build their nutrients.

So that is why you need to give them an alternative light source. And so right after you sow the seed of the auto place the tub under light fixtures.

Autoflower Light Spectrum

While growing auto-flowering plants in an indoor grow room we need to create the environment they habitually grow in; create as much as possible that is. Their natural surroundings include temperature, humidity, and most importantly light.

While gardening indoors, you need the light spectrum that closely mimics the actual sun. In short Full spectrum. Whether you get LED lights or hps bulbs, you need the right amount of light intensity so that your plants thrive perfectly. 

But what is the light spectrum? The light spectrum is the various color shades (aka wavelength) a light source can release. Initially, illumination is calculated in nanometers (nm) and per nanometer accounts for a band of light (a band of light is a segment in the color palette). With bare eyes, people can see only a tiny part of the spectrum, (380 to 780 nanometers).  This means we can only perceive the colors from violet to red.

The sun is a full spectrum light source.  Which means it contains all the colors of the wavelength. All the colors of the palette make the color white. That is why rainbows have seven colors and that is why you will see so many white light bulbs in the market.



In the growing stage, the wild autoflower plants use the blue hue of the sun to promote leaf growth. In the case of autoflower, we intend to grow as many leaves as possible indoors. More leaves mean more upper surface to soak up the grow light. This way you can make sure that your plants develop a fit stem and branches, fixing them up for the flowering stage.

FOR Flowering  The PLANTS

When the marijuana plants enter the flourishing stage, autos in the wild use the red spectrum of the sun to promote sprout formation. So if you want to create thick buds and increase harvest, you need to give your growing plants a red hue. This will maximize the amount of photosynthesis which will increase bud generation

But we recommend you to use a full spectrum light. You can definitely use red and blue light if you can afford it. But full spectrum lights are more efficient in terms of cost and hue. It gives off different wavelengths throughout the growing process.

UV Light: Power ups the sprout and improves trichomes.

Bluish Light: Aids in leaf growth. It is also the reason for the deep green color.

Deep Blue Light: Develops leaves and branches. 

Green Light: Frankly it is the least used hue.

Yellow: Upgrades taste, boasts micronutrients retention, and helps in nourishment

Red Light:  helps In photosynthesis and flowering cycles.

Deep Red Light: Enhances bud quality and harvest

Since all of these hues somehow play a huge part in the development and you can’t frequently buy new lights, we recommend you to use a white full spectrum led grow light. It has a mixture of all the necessary hues to grow a healthy auto.

WHAT is LED Grow Light?

We have been going round and round about Led lights. And naturally, if you have never heard about it, you will be more curious to know about it.

LED lights were invented a long time back; in fact in 1962. And like autiflowers they weren’t widely accepted at first. But as technology advanced, so did the LED grow lights.  Nowadays LEDs have broadened their user facility and breeders have largely profited from that.

See Also  Full Spectrum LED Vs Red And Blue- The Truth You Need to Know

Light Emitting Diodes  ( LEDs) are those types of grow lights that can be used to cultivate almost any variety of plants. In scientific terms, it is made of a lot of small chips (diodes) and encompasses two semiconductors – electrons and protons.

Electrons are charged positively while the protons are negative. When electric power is applied over the LEDs, the two semiconductors become active and clash with each other and emit energy or photons. The whole process in the technical term is called recombination. The PPFD ( Number of photons emitted by the light) was really low in its first edition

Reviews of 7 Best Grow lights for Autoflowering

The first version of LED grow lights didn’t give marijuana growers any kind of advantage, since the light output was lower than other lights. However, after years of research, it all changed. Now high quality LEDs are the only lights that can almost replicate the sun’s full spectrum.

1. MARS HYDRO TS 600W LED Grow Light

TS 600W best grow lights for autoflowering

Key Features

  • Coverage : 2×2 feet
  • True Power: 100w
  • Par Test (PPDF) : 430μmol/m².s
  • Efficiency (PPE): 2.7umol/j
  • Yield (Per wattage): 2.0g
  • LED Type: 225pcs LEDs Epistar SMD Chips

Mars Hydro Ts 600W is one of the best grow lights for autoflowering plants in the market. It’s cheap, it’s powerful and most of all it gives you the most utility. This light closely imitates the natural sunlight so this modern grow light is suitable for every stage of the plant’s growth cycle. In the veg stage, it covers 4 sq (2×2)  feet area and in the blooming stage, it covers 3 sq ft (3×3) area.

It has a light spectrum of 3000k white light, 5000K blue light, 760nm RED light, and 660 nm infrared (IR) light. The perfect spectrum ratio to grow splendid autoflowering plants. The high efficiency level of 2.7umol/j and perfect coordination of wavelength gives you 2 gram yield per wattage.

The full spectrum light is equipped with advanced technologies 225 diodes which not only help to produce superior yield but also consume only 100 true watts. Less power consumption, more quality harvest! This compact light also ensures that you have enough light for the plant’s optimum growth. Which is really impressive for a bulb this size.

The whole light body is covered with strong Aluminum. This reduces the light waste, keeps the bulb cool while also providing 20% more intensity. So you won’t have to spend extra bucks on fans. This LED is truly the perfect light source for indoor gardening.

2. SPIDER FARMER SF-1000 LED Grow Light


Key Features

  • Coverage : 3×3 feet
  • True Power: 100w
  • Efficiency (PPF) : 2.5 umol/J
  • Par Test (PPDF): 1033μmol/m².s
  • Yield (Per wattage): 2.5 gram
  • LED Type: LM201B Samsung chips

This is another best led light for autoflower. Why do we say that? Because it is offering you the latest technologies Samsung LM301B chips at a very low price. The supreme Lumene intensity ( 2.5umol/J) gives you a powerful gleam that perfectly penetrates the plant canopy to boost harvest.  Not to mention the 100 true wattage consumption gives you more bulb lifespan and less electricity bill.                          

The light has the ideal mixture of 3000white ( 3000K), red (660nm), IR(760nm), and 5000K blue wavelengths that are perfect for the veg and bloom stage. The amazing thing about it is that you will get a Meanwell Driver to control the heat intensity. This one covers a bigger area than Mars Hydro. In a veg state, the bulb engulfs 6 square feet (3×3) area and in flowering, it covers about 4 to 5 sq feet.

The perfect light spectrum, enhanced coverage and high efficiency level (2.5umol/J) helps in the growth of the auto flower plants and produces a greater harvest. In per watt, you can easily get 2.5g high quality yield.

Constant fan noise can be quite annoying sometimes. But The light doesn’t heat up due to its Aluminium heat sink, so you won’t have to install extra fans. Enjoy a noise free environment.

From this led grow light manufacturers You will get free maintenance service if you face any problem in the next three years after purchase. Pretty sweet deal huh!

MARS HYDRO TS 600W vs  Spider Farmer SF- 1000 LED Grow Lights For Autoflowering

Features Mars Hydro TS 600W Spider Farmer SF-1000
LEDs 225pcs LEDs Epistar SMD Chips LM201B Samsung chips
VEG COVERAGE 4 sq ft (2×2) 6sq ft (3×3)
FLOWERING COVERAGE 3 sq ft (1.5×1.5) 4 sq ft (2×2)
Per Test (PPFD) 430μmol/m².s 1033μmol/m².s
Intensity (PPE) 2.7umol/j 2.5umol/j



Key Features

  • Vegetative Coverage : 4’x4′
  • Flowering Coverage : 3’x3′
  • True Power: 405W
  • Par Test (PPFD) : 915 μmol/m2/s
  • VEG and BLOOM switches
  • Advanced high speed quiet fans
  • Upgraded aluminum cooling heat sinks
  • Lifesoun: 100,000h
  • LED Type:  High Intensity 240 Chips 5W Epiled/Bridgelux

Since its release the Viparspectra 900W has proven itself to be one of the best led grow lights for autoflowering. It provides just the right amount of light plants would have gotten under natural sunlight. These grow lights can easily replace 600w HPS/MH bulbs while only drawing about 405w. The light covers an 8 sq ft area in veg and a 6 sq feet area in the flowering stage.

The unique thing about this light fixture is that it has two separate light spectrum and magnitude for the veg and bloom. You will find two switches on the top right corner of the bulb. And since you are giving your plants just the right amount of gleam, your plants will return the favor with bigger buds, more fresh looking leaves, and higher yield.

Apart from having an advanced aluminum heat dispersion system, the light is also equipped with a noiseless cooling fan for extra heat protection. Additionally, you will get a 3 years warranty and 30 days satisfaction and return guarantee from the Viparspectra Company.

4. Phlizon CREE 3000W LED Plant Grow Light (COB LIGHT)

Phlizon CREE 3000W LED Plant Grow Light (COB LIGHT)

Key Features

  • Actual Power: 600W±3%
  • Lifespan: 50,000h
  • Core Coverage: 48″48″(44 ft)
  • Maximum coverage : 50″50″(4.24.2 ft)
  • Higher brightness, smaller thermal resistance
  • Par Test at 18″ (PPFD): 2522.8 umol/m²/s
  • LED Type: 2x6000K & 2x3000K COB  plus mixed LEDs
  • light Contains: 6pcs COB, 110pcs 630-660nm, 12pcs 470nm, 12pcs 6500k, 4pcs UV, 6pcs IR

Phlizon CREE COB 3000W led grow light is also very demandable among indoor growers. This is due to its exceptional features. Besides, the  Chip On Board (COB) circuit led lights are much more beneficial and emit a much brighter tone than the regular  LEDs.

These cob lights offer higher illumination along with equal light distribution and little thermal resistance. Like most LED lights in our list, this one also has the right amount of color spectrum of  UV, IR, Red, Blue, and white. And using the veg and Bloom buttons, you can smoothly jump between the light profiles at distinct growth phases.

As the LED has less attenuation and the highest  Photosynthetically Active Radiation (PPFD) rate (2522.8 umol/m²s), it doesn’t have to endure much from burnout. The product is highly long lasting for its  durable fireproof cover,  UV protection, and metal frame

Moreover, Philzon beats MH, HPS, HID, or fluorescent lights in terms of energy efficiency since it only consumes 600 watts. And the Maximum coverage is about 8.4 square feet makes it one of the best led of the decade.

VIPARSPECTRA 900W VS Phlizon CREE COB 3000W grow light for autoflowering

Features VIPARSPECTRA 900w PHLIZON 3000w
LEDs High Intensity 240 Chips 5W Epiled/Bridgelux 2x6000K & 2x3000K COB plus mixed LEDs
Actual Watts 405w 600w
Coverage 4×4 feet 4.2×4.2 feet
Lifespan 100,000 50,000
PPFD value 915 μmol/m2/s 2522.8 umol/m²/s

5. KingLED Newest 1200w LED Grow Lights

KingLED Newest 1200w LED Grow Lights

Key Features

  • Vegetative coverage : 3.5’x3.5’
  • Flowering Coverage: 3’x3’
  • True Power:165W
  • Efficiency (PPE) : 2.8 umol/J
  • Par Lumen Output (PPFD):2300  umol/m²/s
  • LED Type: Newest LM301B LEDs 
  • VEG and BLOOM switches
  • Lifespan: 100,000

Another one of the best LED grow lights for autoflower, the King Plus 1200W helps you to get maximum output with its great features at a cheap rate. It is the ultimate budget friendly product.

The grow light includes  UV &IR spectrum ranging from 380 to 780 nm that is identical to natural light. Like the last two lights in our list, this one also comes with two different switches (VEG & BLOOM). The Veg mode mostly uses blue and white LED lighting for seeding and the Bloom one mostly has red and white for flowering.

However, the thing that makes it unique from the rest is its effective heat distribution system.  It is built with multiple powerful aluminum radiators that keep the bulbs 50-60 F cooler, multiple high speed noiseless fans, and four way vents that enable the lights to perform at a low level temperature. So less plant burn and a higher possibility of healthy plant growth and enhanced safety.

The latest LED technology led lights provide brighter gleam while only consuming 165W. It saves a lot of electricity and a whole lot of money. The light covers a maximum of 8 sq ft area. You can easily grow healthy autoflower plants with it.

6. MARS HYDRO TS 3000W LED Grow Light

MARS HYDRO TS 3000W LED Grow Light

Key Features

  • Veg Coverage : 5’x5′
  • Bloom Coverage : 4’x4′
  • True Power: 540
  • Par Lumen Output (PPFD) : 1274 umol/m2/s
  • Yield (Per wattage): 2 gram
  • LED Type: 1016 pcs LEDs Epistar SMD
  • Daisy chain function up to 15 multi-lights
  • 2 waterproof Mean Well Drivers

Another Mars Hydro TS series grows light on our list. It truly deserves its place here since the light provides you the most amount of features in the least amount of money.

See Also  How many LED lumens Per Plant - The Precise Amount

The full spectrum light has the newest Epistar and SMD technology that not only expands the light intensity by 20% but also supplies a towering lumen output (1274 umol).  Not only that, but the even light distribution also allows the plants to receive more energy without burning them. It has the most coverage area ( 10 sq ft in veg and 8 in the flowering stage) compared to others in our list.

Its advanced scientific method makes it more energy efficient. By only using 450w power the light can help you to produce 30 percent more auto than its predecessors. The light is easy to install and operate so even a beginner can use it pretty easily.

7. Likesuns 1000W inexpensive LED Lights for Autoflowering

Likesuns 1000W inexpensive LED Lights for Autoflowering

Key Features

  • True Power: 120w
  • Lifespan: 50,000h
  • Core Coverage: 42×42 inches
  • maximum coverage : 65×65 inches
  • VEG and BLOOM switches
  • Par Lumen Output (PPFD) : 365umol/m2/s
  • LED Type: 100pcs high power chip

All indoor growers want the best harvest and for that, you need the best equipment. Over the years the 1000w Likesuns full light spectrum grow light has proven itself to be one of the best grow lights for autoflowering.

This powerful light spectrum covers the most amount of area; max 30 square feet. The veg and bloom mode provide exactly the right amount of natural light for maximum yield.

Likesuns 1000w has advanced ventilation and two cooling fans which helps in the process of heat dispersion. It keeps the environment cool and also less prone to plants hating up. The modern LED chips give you more brightness than 1000 HPS/MH/HID bulbs.

The light is highly efficient with a per lumen output of 365umol/m2/s  while also only consuming 120w. It not only saves money but also gives you a lifespan of 50,000h or maybe even more. And of course, Likesun Company will give you 24 hour service to ensure maximum satisfaction.

Now that you know what sort of light you will buy, You need to know what LED wattage you need to grow your auto flowering plants.

Best Wattage for Autoflowering (Per Square Foot)

Generally, 32-50 watts per square foot is needed at the blooming stage and a half for the veg stage. You will see different opinions over the internet.

Suppose you are growing an auto that takes the area of 2×2 which means 4 sq ft. So you can either buy a LED grow light that covers the total area or you can buy 2 separate light fixtures. If you buy two lights with 32-50 watts of power then the total amount together is 100 watts. Or you can just buy one hundred watts per square foot fixture.

And so in that way in the vegetative stage, your plant will need near about 50 watts.

Each LED grow light will have a distinct level of proficiency. Superior LED will need fewer watts to discharge the same volume of light than a less efficient LED grow light. So quality matters more than watt percentage. Suppose you have one premium 300w led light and another low quality 300 led wattage. The output will be greater on the elite ones.

 Hence, as I have mentioned, wattage is not the most precise quality to measure how powerful light you could possibly need per square foot area.

How Many Lumens Per Autoflower

Lumen is the total number of light a grow bulb can emit. And naturally, more is always better. So how much does each plant need in your grow room?

 Ideally, the pro breeders agree that for per square foot you need around 2000 to 5000 lumens.  So suppose you have 4  square feet of grow area. So you would need a total of 16000 to 20000 lumens. It doesn’t matter the number of plants you are growing in that space. 

That is to say, you shouldn’t just try to plant as many plants as you can in that area. Because when your marijuana plants start to brunch out they will need space. And if you don’t give them much space to spread they won’t give you a premium yield. Try to grow 3 or 4 plants per square foot.

So in that way one plant will get around 500 to 1250 lumens from par LEd grow light.

Growing Autoflower with Led grow Lights

Though it’s not mandatory, we highly recommend breeding autoflowers under LED lights.  There are few reasons for this

Firstly, the full spectrum light they emit;

Secondly, their long lifespan

Thirdly, perfectly balanced heat

Fourthly, higher efficiency light output

Full Spectrum

Obviously, You can grow your plants as you feel like. As long as you do it perfectly, you’ll have sizable yield output.  But as autos have a short life cycle, it’s important to grow them beneath the finest lighting you can find in the market. Always keep in mind, a premium grow light does not only bring out the intensity that the plants need in your grow space but also provides a hue that will stimulate your plants to showcase their maximum potential.

Suppose we are comparing three same variants of auto grown in the same conditions. But one being grown under a full-spectrum LED grow light, another beneath the t MH  bulb, and the last under HPS light. What do you think will happen to these plants?

Well,  it is most likely that the plant under  LED grow light develops better than the ones under Metal halide and high pressure sodium. This is because the led grow light gives the plant all the wavelengths it could get in nature.

Increased lifespan

LEDs or light emitting diodes can live up to 50,000 hours. Some even go up to 100,000. This amount is way more than any other bulbs. This is because the diodes implemented in the lighting keep it cool. Other grow lights discharge a lot of heat. And that extra energy lowers their lifespan. So in conclusion, although bulbs initially come across as cheaper,  you will have to change them often which in the long run could cost you more than LED grow light.

Less Heat

LEDs discharge less heat than bulbs while maintaining the same intensity while withdrawing less power.  You can find LED fixtures that come with fans.  However you won’t need it as long as you have a quality led light with good diodes,  and extra fans & a well built ventilation system in your tent.

Obviously, there are all sorts of  LEDs in the market. And trust me when I say this, you will see that most of these grow lights lose to bulbs. However,  if you are ready to invest in your indoor garden, a high-quality LED will give you extraordinary results. You could easily compare and identify the difference in caliber, thickness, and trichome production of your cannabis plants in different lighting.

Higher Efficiency, Less Energy Usage

Apart from less heat production, the light output of the led grow lights are exceptional as well. Due to LEDs having more power, they can make more with less energy. LED fixtures to utilize whooping 75% less energy and at the same time give the same or 2 x  more lamp intensity.

For better understanding let me give you the exact number. LEDs use 12 watts to lit. Equivalent to that power is a 50 watt bulb. So you need a less light source. So less cost while purchasing and also maintaining. Plus you will save a lot of electricity.

Note:  pricy LEDs don’t do magic.  They are just bulb fixtures.  So you still need to modify your tent setup.  Because even the greatest  LED grow lights won’t produce a smashing output if the other conditions (temperature, nutrients, and humidity.) are not up to the mark.

So get a lot of knowledge and put together your whole grow tent or grow room before deciding to spend $1000 on LED grow lights.


How many LED watts per autoflower

Led grow lights are the only efficient and cost-effective method to grow autoflowers. Though it is the ideal choice, not just any wattage will do the trick. You need to at least incorporate the bare minimum watt for the plant to grow.

 So what watt led should you install per autoflower?

I have given you the detailed watts chart below assuming you are blooming your plants. But in case you are vegging, you need to reduce your wattage by 50%  for greater efficiency. Since in the autoflower vegetative stage plants don’t need that much light intensity, power, or heat.  And as always, we recommend you follow manufacturers instructions before doing anything.

Using the charts

Before going to the chart let me clear some phrases for you. In each chart you will find the following columns:

  • The square feet coverage of the plants
  • ‘# of Plants’ to be grown
  • Suggested LED wattage for the number of plants grown in the specific area.

Quick Guide (wattage per coverage area)

Here is the mathematical term for feet

  • 1′ x 1′: 32 W (~30 to 40 wattage)
  • 2′ x 2′: 128 W (~120 to 140 wattage)
  • 2′ x 4′: 256 W (~240 to 300 wattage)
  • 3′ x 3′: 288 W (~250 to 300 wattage)
  • 4′ x 4′: 512 W (~500 to 650 wattage)
  • 5′ x 5′: 800 W (~700 to 900 wattage)
  • 4′ x 8′: 1024W (~900 to 1100 wattage)
  • 6′ x 6′: 1152 W (~1000 to 1200 wattage)

Minimum and Ideal Watt Par Plant

Number of PlantsMini LEDs Watt (Low intensity)Mini LEDs Watt (Mid intensity)Mini LEDs Watt ( High Intensity)Ideal LEDs Watt (Low Efficiency)Ideal LEDs Watt (Mid Efficiency)Ideal LEDs Watt (High Efficiency)
152 watts43 watts35 watts69 watts46 watts100 watts
2104 watts86 watts69 watts138 watts92 watts200 watts
3207 watts171 watts138 watts276 watts184 watts400 watts
4310 watts257 watts207 watts414 watts276 watts600 watts
5414 watts343 watts276 watts457 watts369 watts800 watts
6517 watts429 watts346 watts571 watts461 watts1000 watts

One thing you need to know is that the listed wattage is not actually the power LED lights extracted from the wall. We incorporated the estimated bulb equivalent just in case the providers don’t write the actual wattage.

See Also  How To Use Ozone Generator In Grow Room?

Best Light Cycle for Autoflower with LED Grow Light

Each pro breeder has their own techniques of harvesting. But most agree on one thing that the minimum amount of light to give auto strains is roughly about 18 to 24 hours. You should adjust your led grow lights based on the cultivar you’re growing

Well, there are four light cycles for you to explore: 12/13, 18/6, 20/4, and 24/0 24/0 (the first digit is the light hours, the second is the dark). You can always customize the schedule as long as the plants receive more than 12 hours of light a day. For instance 16/8, 19/5, 16/8, etc.

Growers always experiment with their schedule but if you are new just stick to the ones we describe.

Note: we are only mentioning the schedule suited for LEDs.

24/0 light schedule for autoflowers

Plants usually grow faster when they get more light. This schedule is a good choice if you live in a cold climate, keeping the lights turned on 24hrs a day will keep your autoflowers warm.

Obviously, this is the easiest autoflower light cycle as you don’t even need a timer, just turn on lights until harvest.


Doesn’t require a timer.

May result in the best yields.


Uses more energy, can get expensive

Finishing autoflower on 12/12

Though it is not favorable, some breeders still favor the 12 hour schedule. They mostly use this cycle in the flowering stage. It has proven to be a safe option too as plants grown in these lite circumstances can still yield a good harvest.

If you choose to do this you need to keep one thing in mind that the buds you grow under a 12 hour lighting schedule will look tinier compared to what you would have gotten under an 18–24hr light cycle.

But still here are some reasons in its favor:

To save money: Money is a big factor, no doubt. And keeping some lights on for 18-24 hours can be pretty costly. And sometimes all these can scrape some light lifetime too. Cause you to buy more and more light. So 12/12 can be a cost effective option if you have a tight budget.  And other appliances will be switched off at that time too. Meaning you will save energy and obviously money.

Heat concerns: In a tropical or heated environment too much light operation can be dangerous. Keeping the lights on for 18-24h can cause a lot of heat. These excess amounts of heat can harm your plants and other appliances too. So what you can do is keep them on at night while the temperature outside is cool and then keep the light off on the day when the sun is on the horizon.

Autoflower 18/6 LED light cycle

Most breeders would tell you one thing that the ideal amount of light your autoflowering strains need is somewhere between 18-24 hours of light per day.

And The 18/6  cycle is the most popular one among the growers. Why though, right? Well! Because it supplies more than 16 hours of light. Even though autoflowers don’t need a specific amount of light to grow, it needs the necessary amount of light to make food and sustain.  And the 18 hour provides the plant with an opportunity to work at its full potential. Not to mention the six hours resting period is downright perfect time for the plant to replenish and rejuvenate.

With enough darkness or a relaxing period, the plants have plenty of time to recover and flourish. It is also a perfect schedule for new cannabis growers who are really alarmed by autoflowers. Autoflowers are programmed to grow as quickly as possible and they begin to flourish right from the get-go.

You can’t afford to stress the plant because it becomes difficult for the plant to bounce back. During a 24/0 light cycle, there’s no time for the plant to fight against stress, but an 18/6 cycle provides six hours that can be used by the plant to recuperate.

Your light also needs a break from time to time. When they work continuously without stopping, they often heat up and damage the plants. So it is advised that you give your lights a time out. Also, it will cool the room too. After a long day of heat, your room needs to cool up too.

The exact same argument can be made for your other appliances as well. For example your fans,  air conditioners, and just about any other electronic devices you use to manage the temperature of your indoor garden. Your devices will give you long term utility if you give them some time to breathe from all the hours of work.

And the last point I would like to make in its favor is that you save a few extra bucks and energy even if you are reducing just 6h of light each day. If you do a mental calculation, you would see that you are saving about 180 hours of light per month. All this logic does tip the scale in its favor, huh?

Do Autoflowers need darkness?

Well, Technically speaking, the autoflowering plants don’t necessarily need darkness. It is because its predecessor, the Ruderalis is used to the 24 hours of natural sunlight. So the best thing about them is that you can grow them in any light schedule, that is if the environment and the temperature favor them.

Even in the forest, the Ruderalis don’t entirely depend on light to flourish. When the plants reach a certain height they naturally start to flower. The buds start to form after the plants grow some branches or leaves.

However, these new strains of autoflower are different from their predecessors that grew in the wild. And even they needed some light to make their necessary nutrients. So it is true that we can’t now deny it anymore that we need to give autos a proper amount of light to sustain and grow.

However, we have already mentioned several times that a 24 hour light schedule may put too much stress on the plants. It leaves no practical work for the grower either. Some may even neglect their plants thinking they are doing everything by just constantly keeping the lights on. And by doing that the plants get deprived of much needed time to rest and relax. Ruderalis plants that grow in the wild have adapted to the harsh conditions after years of the ecological system and now they don’t have any problem with that environment whatsoever.  But we are not growing those wild breeds, are we?

Though I agree that the autos strains we have today are strong and fight against many minor or chronic diseases with a unique ability to adapt anywhere. However, we can’t really compare them with the ones that grow in the wild forest.

So to summarise, we suggest you some amount of rest per day as the plants need a few moments of darkness for some metabolic processes.

When to Put Autoflower under Hps (High Pressure Sodium) grow lights

To cannabis growers, HPS lights are not a new name. However, most autoflower breeders don’t use them and won’t advise you to use them either. Because in Lumene and watt competition it looses to LED on a high number. But still, you can use them in two cases.

  • Firstly in a big project where you have a huge space of autos. Since HPS lights produce a huge amount of heat, you can easily use HPS lights on there.
  • Secondly in the blooming stage. HPS bulbs have a huge amount of red light spectrum. So you can place your plants under this light once your plant enters the flowering stage.

People also ask

1. What is the best light schedule for Autoflower in the grow tent?

We think that the ideal one is 18/6.

But then again some think it is 12/8 or 20/4. You need to decide for yourself. And since autoflowers don’t need much of a lighting schedule, you can experiment with them.

2. How many square feet are needed per Autoflower?

Well, a plant needs about 2-4 square feet area to grow. So in a 4×4 grow tent you can easily breed One plant.

3. Do Autoflowers need red lights?

If you are not using full spectrum lights then yes, your plants will need red light to make nutrients and grow. In full spectrum bulbs, you will already have reddish light installed in them. But if not then you have to buy separate red light and blue light for plant growth. All the color spectrum together makes white light.

4. What lights do I need for my autoflowering plants?

You need full spectrum led lights for maximum Utility. We have recommended some of the best LED grow lights for you in our article.

5. Do autoflower need total darkness?

No, autoflowers don’t need total darkness. They need to absorb light to make food for their growth.


LED lights are the best edition of the indoor gardening world. You can grow different sorts of herbs, fruits, and cannabis due to this light. And since autoflower grows spectacularly well due to its natural light spectrum, it is safe today that investing in it is a safe bet for newbies and experts alike.

Your plants need the best equipment if you want to grow them in an artificial environment because it is not their procedure. So buy one of the best grow lights for your autoflowering and get the finest result.

Note:  Remember you need to set a good environment for your plants too. And more importantly, your autos need love and care to thrive and grow.

Leave a Comment

Your email address will not be published.

64 + = 73