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The Best Grow Lights for a 3×3 Grow Tent – Pictures, Specs, and More

What are the best grow light options for a 3x3 grow tent? Consider one of the following options: A Viparspectra P1500 (budget), A Mars Hydro TSW 2000 (performance), an Optic 4 Gen 4 (Fancy), or a 250 watt HPS grow light (HPS option).

The most important factors to consider when choosing a grow light for a 3x3 foot grow space are the light intensity and uniform coverage area of the lights.

If you pick the wrong grow light your plants won’t grow to their full potential. All the options I mention below meet or exceed those requirements.

When you’re done reading this, don’t forget to check out my article on choosing the right size fan for your grow tent.

Budget Choice: Viparspectra P1500

Viparspectra P1500

   (Click Here to View or Buy at LED Grow Lights Depot)

The Viparspectra P1500 is the most modern design LED grow light from Viparspectra, a grow light manufacturer that has been around long enough to sell several generations of best selling LED Grow lights.

I bought the smaller P1000 model and wrote about it here.

This P1500 model will veg and flower your 3x3 foot grow tent. Is it the best performing or most powerful? No, but at ~$160 it offers a solid bang for your buck if you’re on a tight budget.

Why Choose Viparspectra P1500 for your 3x3 Grow Space:

I speak with growers who swear by their Viparspectra grow lights. As a matter of fact, they won’t switch to another brand despite there being options that offer higher performance.

These Viparspectra owners also swear by the reliability. The enthusiasm around Viparspectra is a great thing to see for a brand.

The dimming knob is very convenient. The fact that this Viparspectra P1500 isn’t overly powerful allows you to hang it close to your plants, saving you overhead space.

The light intensity is strong enough to cover a 3x3 foot grow space, preferably a grow tent for increased light reflection.

Viparspectra P1500:
Watts Consumed:150 watts
Peak Intensity:1000 micromoles (enough for seed to flower)
Coverage Area:Flowers 3x3ft
Spectrum: 640-660nm (far red), 3000-3500K (white), 6500-7500K (white)
Warranty:3 years
Where To Buy:Click Here
Video of my Viparspectra Grow Light:
Viparspectra P1000 Pro Series Grow Light | Test & Overview

Performance: Mars Hydro TSW-2000

mars hydro TSW 2000

(Click Here to View or Buy at LED Grow Lights Depot )

The Mars Hydro TSW-2000 is a modern quantum board style LED grow light. This grow light is rated for 3x3 feet of flowering coverage, slightly larger for vegetative growth.

I bought a different size Mars Hydro model for my 2x4 grow tent at home and it looks and performs great. This is one of the best selling LED grow light brands around.

Why Choose Mars Hydro TSW-2000 for a 3x3 foot Grow Space:

This TSW-2000 is a bit more powerful than the Viparspectra P1500 listed above. For that added performance, plus a few other features, you’ll pay a bit more.

With that said, if you have the money it’s totally worth it. The stronger light will result in better yields in your 3x3 foot grow space. You can remove the drivers on the TSW-2000 and hang them outside the grow tent with the extra cord length. This helps you keep your growing temperature down.

The spectrum coming from the TSW-2000 is similar to the Viparspectra (white + red) except the Mars Hydro also contains infrared, which helps plants resist any potential disease, and grow more dense buds.

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Mars Hydro TSW-2000:
Watts Consumed:310 watts
Peak Intensity:1150 micromoles
Coverage Area:Flowers 3x3 feet
Spectrum:3000K (white), 5000K (white), 660nm (red) 760nm (infrared)
Voltage:120v / 240v
Warranty:3 year
Where to Buy:Click Here

Take a look at the buds people have grown with Mars Hydro grow lights:

mars hydro cannabis

Video of My Mars Hydro Grow Light:

Mars Hydro TSL-2000 Grow Light | Test and Overview

Click Here to See Prices and Reviews of The Mars Hydro TSW-2000 at LED Grow Lights Depot


Fancy Choice: Optic 4 Gen 4 COB LEDs

optic 4 gen 4

(Click Here to View or Buy from Optic LED)

The fancy, high performance grow light option for a 3x3 foot space comes from another reputable LED grow light manufacturer, Optic LED.

This COB LED differs from the previous two 3x3 foot grow light options. It differs because COB LEDs are stronger, so you’ll pay for that. But you’ll read below why you get what you pay for with the Optic 4 Gen 4.

Why Choose Optic 4 Gen 4 grow light for 3x3 foot space?

Although I haven’t personally owned or tested this brand, I’ve personally spoken with owners of just about every grow light brand. Optic LED is another brand that I’ve heard growers swearing up and down by.

There are three reasons why you get what you pay for when you pay a higher price to hang the Optic 4 Gen 4 grow light in your 3x3 foot grow space.

The first reason is the larger vegetative growth coverage area. The Optic 4 Gen 4 flowers 3x3 feet, but with the high strength COB lenses, you’ll actually be able to grow plants in a 5x5 foot space until they’re ready to flower. Then you’ll have to shrink to a 3x3 foot space.

The second reason is the Ultraviolet and Infrared spectrum. I’ve noticed that Ultraviolet spectrum being included on grow lights is pretty much going extinct.

The reason is unknown because ultraviolet rays are documented to increase THC levels. My guess is grow light manufacturers want to save money (what else is new?).

Infrared spectrum is also documented to help plants grow thicker stems and more dense buds, and it’s included on the Optic 4 Gen 4.

The third reason is the very strong light, as you’ll see in the image below. Advanced growers, or growers who plan to use CO2, should take advantage of a high performance grow light like the Optic 4 Gen 4 because you need this level of intense light when using CO2. The previous grow lights I listed are not this strong.

optic 4 gen 4 ppfd

When you put a Optic 4 Gen 4 grow light in your 3x3 tent you’ll be getting all of these benefits.

Optic 4 Gen 4 Specifications:

Optic 4 Gen 4
Watts Consumed370 watts
Peak Intensity:1700+ micromoles
Coverage Area:3x3 ft flower / 5x5 ft veg
Spectrum:660nm (red), 460nm (blue), 3500K (white), UV, IR
Voltage:120v / 240v
Warranty:10 years!
Where to Buy:Click Here

If you don’t mind paying extra for a top-shelf product, the Optic 4 Gen 4 is absolutely your match. Especially if you’re growing in a 3x3 foot area.

HPS Option: 250 Watt HPS Grow Light

(Click Here to View or Buy on eBay)

If you have a 3x3 foot grow tent, and don’t mind using a non-LED grow light, you may want to consider a 250 watt HPS grow light. This FloraLux grow light is priced nearly the same as the budget Viparspectra option above, but will provide you stronger light.

Of course, this light uses 100 extra watts compared to the Viparspectra P1500. Should you worry about heat when you put a 250 watt HPS grow light in your 3x3 foot grow space? At 250 watts I wouldn’t worry too much. You really only have to be careful when you get to 400 watts and above.

Why Choose a HPS Grow Light for a 3x3 Foot Grow Tent?

  • Flowers a 3x3 foot space.
  • Offers the performance of a more expensive LED grow light at a budget price.
  • Relatively low 250 watt consumption.

Click Here to View or Buy the FloraLux 250w HPS Grow Light on eBay

FloraLux HPS Grow Light
Watts Consumed:250 watts
Coverage Area:3x3 feet
Spectrum:Red & Blue spectrum bulbs sold separately
Where To Buy:Click Here

Which of these grow lights would I personally choose for a 3x3 foot grow tent?

Growers often ask my opinion after reading my lists. My personal choice for a 3x3 foot grow tent would be either the Mars Hydro TSW-2000 or the Optic 4 Gen 4.

Both are very good lights and I think you’ll be very satisfied with either one. The Viparspectra could be a little stronger, and I’d personally rather have an LED grow light than an HPS grow light.

I don’t recommend the 250w HPS, but occasionally I talk to people who are on a tight budget. If that’s your case you can go with one of those.

Is 3x3 feet the best grow tent size?

In my opinion, 3x3 feet is not the best grow tent size. You can fit one to two plants, but with the recommended spacing of 2x2 feet per plant, fitting even two plants plus a humidifier can get cramped quickly.

I prefer 2x4 foot grow tents, or 4x4 foot grow tents. I’ve outlined the best grow light options for 2x4 foot grow tents here, and for 4x4 foot grow tents here.


How many watts do I need to grow cannabis in a 3x3 foot grow tent?

The smallest number of watts needed to grow cannabis in a 3x3 foot grow tent is 40 watts per plant, although the best grow lights use at least 200 watts for the whole tent.

How many cannabis plants fit in a 3x3 grow tent?

Two cannabis plants will fit in a 3x3 grow tent. It can vary depending how large the plants are allowed to grow.

What size inline fan should I use in a 3x3 grow tent?

An inline fan rated for 150 to 175 cfm will be sufficient for a 3x3 grow tent.

How do I control temperatures in a 3x3 grow tent?

If your grow tent is too hot, try cooling the room where the tent is located by opening a window or using an air conditioner. If the grow tent is too cold you may need to buy a space heater for the room the tent is located in.

How do I control humidity in a 3x3 grow tent?

You can control humidity in your grow tent by using a humidifier or dehumidifier.



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.