Starting an indoor grow operation can be overwhelming for beginners since there is a lot to consider to make sure your plants grow healthy. One of the significant aspects of any indoor growing system is the lighting, and most people can assuredly say that LED lights are the way to go. The question that immediately arises is: what size of grow light do I need?

There are various brands and types of LED grow lights available on the market and choosing the right one isn’t the easiest task. Most first-time indoor growers don’t have any knowledge about the requirements of their indoor garden in terms of space and size.

You’d like to get a LED to grow light system of adequate size to accommodate your garden for efficient growth. So, what size of grow light do you really need?

Well, the size of your grow light mainly depends on three factors.

1. The type of plant you’re growing

Before getting any sort of grow light, growers need to consider the nature and species of the plant they’re growing. You should know that LED grow lights of all sizes can accommodate typical seedlings so they reach complete maturity.

With that being said, some plants require larger LED grow lights that provide more power, energy, and surface area. You can find LED lights with sizes that specifically assist different types of crops according to their needs.

2. The potential size of the growing space

The grow space area that you set up for your indoor growing garden essentially helps decide the size and number of LED grow lights that you will need to accommodate the traffic and surface area. When growing indoor plants, a good rule of thumb is to use a minimum of 32 watts of LED supply to light every square foot of growing space.

Consider a situation where your grow area is limited to about 16 feet. Your LED growth lighting requirement would, therefore, be around 500 – 550 watts. Plants that grow well under such intense light should then be able to bloom and flower, whereas vegetables and fruits usually need about half the amount of LED light that has been recommended above.

3. The type of LED grow light

Programmable LED grow light apparatuses are the most technologically advanced of all the present systems that are found in today’s markets. They are mostly recommended since their LED panels are geared with one-touch control systems that help growers avoid any unnecessary manual hardships and input needed to get the desired light output for each stage of their plant’s life.

For efficient and easy growing, most programmable LED lights come equipped with hardware designs that accommodate any kind of plant garden, so you can choose from their various sizes to suit your garden.

Grow variables

It is important to understand that the number of actual watts that you need for your grow will vary depending on:

1. Plant type (high light or low light)

• High light plants - i.e. tomatoes, peppers, etc
• Low light plants - i.e. herbs and leafy greens (such as basil lettuce)

2. Growth phase

• Seedlings, vegetative, and flowering plants all require a different amount of light
• Total area of your grow
• A larger grow area will require more power

How to calculate grow light wattage requirements?

Most flowering plants grow best with 20-30 watts of light per square foot. Don’t make the mistake of thinking more is better. Too much light can lead to bleaching and burning your plants. 

Let's say you are growing in a 5’ x 5’ grow space. If your plants need 20-30 watts/square foot, and your canopy takes up 4’ x 4’ of that space, you will need 320-480 watts of grow lighting. That is calculated on basis of 4’ x 4’ space instead of 5 x 5 grow space.

So how many grow lights do I need?

As far as you know how many total watts of grow lighting you need, it’s not difficult to get an answer of how many lights you will use for indoor growing.

Let’s take this 5’ x 5’ grow example, the space is big enough where two grow lights could be an option. When you choose 2 LED grow lights (P2000) with 200W actual power per unit, you may cost 398 dollars in total.

However, it seems to make more sense to use one large grow light (XS2000) with 480W actual power. But you only spend 270 dollars on one grow light fixture, saving 128 dollars at one time!

Therefore, the number of grow lights your room will need really depends on the real performance of it. Grow lights have gotten more and more powerful as technology continues to advance. No matter one or two grow lights, it is the actual power and real cost that matter most!

There are some high-performance LED grow lights suitable for various sizes of grow tents.  They provide solutions for growing from a minimum of 2’ x 2’ grow area to a maximum of 5’ x 5’ grow area.

XS1500

XS2000

XS4000

Quick Guide (watts per coverage area)

1' x 1': 32 watts (~30 to 40 watts)

2' x 2': 128 watts (~120 to 140 watts)

2' x 4': 256 watts (~240 to 300 watts)

3' x 3': 288 watts (~250 to 300 watts)

4' x 4': 512 watts (~500 to 650 watts)

5' x 5': 800 watts (~700 to 900 watts)

4' x 8': 1024 watts (~900 to 1100 watts)

6' x 6': 1152 watts (~1000 to 1200 watts)

Note: The above data is referred from ledgrowlightsdepot.com.