Best Light for Growing Weed in Closet

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Space and money are two common challenges you are likely to face as a home marijuana grower. Perhaps you have a small space for growing weed and don’t have a large budget to spend on the setup.

Regardless of the small space, you still want to get the highest yield from your buds.

In this article, we will cover everything you need to know about growing weed in small spaces. Apart from this, we will answer the question, “Which is the best light for growing weed in closet?”

You can use the Table of Contents to scroll to different parts of this article. However, if you are fairly new to indoor marijuana growing, you may want to read the whole article.

Table of Contents

How Much Space Do You Need for Each Cannabis Plant?

Growing cannabis is a fun hobby. To get a good start, it’s important to know and address your grow area. Before you start looking for the best grow lights, there are a number of things you should consider:

Square Footage

Take advantage of every space in the closet. You have to calculate the closet area to determine the best lighting to use.

Light Spectrum

The light spectrum plays a crucial role in maximizing plant yield. The light should cover the entire growing process, from seedlings to vegetation to buds without being too much of an inconvenience or expense.


Since we want to grow weed in a confined space such as a closet, HIDs are out. These bulbs produce a lot of heat and will require ventilation. Depending on the size of your closet, under 5×5, the lights are impractical.

For growing marijuana in closets, the best lights to use would be LEDs and Compact Florescent Lights (CFLs) as they produce less heat.


Finally, consider the amount you are ready to spend on your grow room as well as lighting.

Figuring Out the Amount of Space Each Weed Plant Requires

Growing too many plants in a small area will reduce your total yields. Moreover, you do not want to waste the available closet space by failing to utilize the whole of it. Continue reading to find out how many plants you “can” grow.

What is Your Grow Method?

Some weed grow methods require more space than others. Therefore, you should consider the grow method that you prefer.

Below are two different grow methods that have different space requirements per weed plant.


The “Low Stress Training” grow method involves training the plants by pulling them vertically. When you get more experienced in LST, you can grow your plants up to 5feet of space.


Also known as the “Sea of Green”, this grow method can be used when you have minimal space. The plants can thrive in 12: of space.

If you are a beginner, we will elaborate a basic, simple grow that uses no real grow method.

  • Seedling to early vegetation: 1 foot per plant
  • Vegetation to flowering/budding: 16″ to 18″ circumference, or about 15 sq/ft.

With the above options, we are playing it safe for a full grow and plan on having a short vegetation stage. For advanced growers, each plant would need a minimum of one foot.

Here’s an example:

Let’s say that you are growing in a closet that is 3″x3″ space.

3×3 = (9 square feet)/(1.5 square feet per plant) =  6 plants

How Many Watts/Lumen Will Each Plant Require?

There are two ways by which you can calculate the amount of light that you would need: Watts and/or Lumen. Most people opt to measure in Watts as it’s easier. If you prefer to measure in Lumens, you can use a Lumens to Watts calculator to ensure you have the correct measurements.

Here’s an overview of the conversion:

  • 10 Watts from LED produces about 600 lumens
  • During vegetation, each square foot should receive 2500+ lumen
  • During flowering, each square foot should receive 10,000+ lumen

Continuing with our example from above, we would need:

(3’x3′) = (9′ grow room or 6 plants ) x (10,000lm Max) = (90,000lm or 150watt)

From the math, it’s evident that the real cost of LED grow lights should not be too much. When you consider the low heat output and energy savings, it is easy to see why LEDs are the best lighting for stealth grows, closet/small grow rooms, and even commercial-level setups.

Grow Light Spectrum

Grow lights spectrum is quite a huge topic that would be best tackled through a separate article. In this section, we will just cover the basics.

All plants go through a natural light cycle that is part of the changing seasons and its environments. You should know how these natural light cycle and seasons affect the growth of the plants. Moreover, you can also alter the grow rates of your plants by controlling the indoors light cycle.

Visible Light Spectrum

Wavelength is the unit used to measure light. The visible spectrum lies within 300nm to 800nm. When it comes to growing weed or indoor plants, this is the spectrum that is useful to us.

Any lighting source that can cover this range effectively is referred to as “Full Spectrum” lighting.

While it may be nice to mimic the whole range indoors (300nm – 800nm), it is not really necessary for good grow and high yields. The entire range is represented in nature but not the whole of it is required for photosynthesis.

For Better Yield, Maintain 400nm to about 750mn Light Spectrum

400nm to 550nm Spring to Mid Summer Vegetation
550nm to 750mn Mid Summer to Autumn Vegetation to Flowering (Budding)

Most LED grow lights are power-efficient and produce less heat than standard grow lights. However, not all LEDs are the same. There are a number of things you should keep in mind to find the best LED light for growing weed:

  • Space required
  • Lumens
  • Spectrum
  • Lifetime
  • Cost per Watt

CFL Color Temperature (or Kelvins)

If you are new to growing with fluorescent lighting or CFL, you may not know what “Kelvins” is. The concept is, however, simple.



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Best Light for Growing Weed in Closet

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