Best Lights for Growing Marijuana Indoors

No ratings yet.

Best Lights for Growing Marijuana Indoors

Marijuana needs light to grow. For outdoor growers, this is supplied by the sun but indoor growers need to replicate the sun in their grow room using marijuana grow lights.

In this topic you should come out with an understanding of the terms used in lighting, the types of marijuana lighting available for your marijuana grow room, and the light cycles you will need for the different stages of your marijuana plant’s life cycle.

Lumens and Kelvin
The main terms used when people refer to light in marijuana growing are lumens and kelvin, which are the brightness and warmth of light. Lumens are a measurement of the total amount of visible light and Kelvin is a measure of the color temperature the bulb is emitting. Light is comprised of separate bands of colors, with each color sending the plant a different signal and promoting different types of growth. These contrasting color signals mean you require different marijuana grow lights throughout the various stages of your growth.Best Lights for Growing Marijuana Indoors

Vegetative growth
You need a bulb that emits light from the blue end of the spectrum as it imitates the midday sun of summer. The recommended light will be 6500k.

When flowering your plant, you will need a bulb that imitates a similar light of fall or autumn, which is towards the red end of the spectrum. A bulb that is 2700k will be suitable for flowering.

Brilliance is used to discuss the clarity and the sharpness of the light as it gets further away from the source, or in this case, the bulb. As you get further away from the light source, its brilliance deteriorates. This affects how far away you keep the plant from your marijuana grow lights:: too far away and you’ll stretch and weaken your plants; too close and you’ll burn and damage them.

The wattage you use affects the amount of space your light will cover; the higher the wattage, the larger the surface area covered. For example, a 1000-watt bulb lights a larger surface area than a 600-watt bulb. The type of light you are using and the amount of space you are growing in will affect the amount of wattage you will need.

This section will explain the different lighting options available, how to use them, as well as very basic pros and cons.

What are they?Fluorescent tube
Fluorescent tubes are long glass tubes filled with inert gases. They come in a selection of lengths and are available in a variety of different color spectrums, emulating the spectrums found in sunlight. Most growers use fluorescent tubes on clones to maintain mother plants. They can be used for flowering, but the buds and yield will be poor, making it not worth your while. Also, the light brilliance from fluorescent tubes degrades rapidly.

Best practice:
To get the most out of fluorescent tubes, you will need to keep them 6-8 inches away from your plant. They are good for use on clones and seedlings or for vegetative growth. Try to avoid using them for flowering.

$80 for T5 Grow Light 2 Tube – $220 for T5 Grow Light 8 Tube.

20,000 hours.

-Excellent for seedling and clone growth.
-Low Running Cost.

-Not good for flowering.
-Bad light penetration.

What are they?
Compact flCFL bulbuorescent lights or CFLs are similar to standard fluorescent tubes, but are smaller in size and boast increased power. They are available in both daylight (6500k) and warm/soft light (2700k) and generate very little heat so are ideal for smaller grow spaces.

Best practice advice:
If you’re using CFLs as your weed grow lights, you are better using more, lower wattage bulbs to spread the light around the plant. You will need to keep CFLs close to your plant as they have poor light brilliance. Increase your light coverage and penetration by hanging lights around the side of the plant.

20,000 hours

What are the Costs?
$40 for a 100watt bulb.

-Good for small grow spaces.
-Low running cost.
-Do not require ballast.
-You can get them from home depot.

-Not suitable for larger grows.
-Lack penetrative power so need to be kept close.

What are they? LED Grow Lights
Unlike HID lights LED grow lamps contain no filament to burn out and therefore have an extremely long lifetime, making them an ideal hydroponic lighting choice. For many, LED lighting is seen as the future of indoor growth as it has extremely efficient running costs that are a fraction of HID and CFL lights while generating very little heat.

Best practice advice:
LED grow lighting runs at very low heat, meaning you can grow your plants right up to the light without overly worrying about heat burn.

60,000 hours

What are the costs?
$900-$1000 dollars for 400watt HID equivalent.

-Extremely efficient.
-Lamps are at a fixed angle so all light is directed at the plants.
-Run at low temperatures.
-Long life.

-Extremely expensive initial cost.
-Currently do not produce the same quality weed as an HID marijuana lighting set up.

What are they?
HID or High-Intensity Discharge lamps are the most common type of marijuana grow lights used for indoor growing and are arguably the most efficient way of producing good yields indoors. The HID family includes Metal Halide (MH) and High-Pressure Sodium (HPS). HID lamps produce the perfect spectrum for both the vegetative and flowering stages of marijuana growth.

What are they?Metal halide bulb
MH or Metal Halide is currently the most efficient source of artificial white light available to indoor marijuana growers for vegetative growth. MH bulbs come in a range of watt sizes, including; 175, 250, 400, 600, 1000 and 1100. The most popular indoor growers are the 400 – 600 watts.

Best practice advice:
A metal halide bulb’s light spectrum and 6500 Kelvin temperature are perfect for the vegetative growth stage of your marijuana plant. MH bulbs have excellent light brilliance but produce a lot of heat.

10,000 hours.

What are they?High pressure sodium bulb
HPS or High-Pressure Sodium is an extremely efficient bulb that emits an orange light spectrum, mimicking the sun of fall/autumn (2700K). Like MH bulbs, HPS come in a range of watt sizes. The most popular indoor growers are the 600 watts.

Best practice advice:
To get the best out of your HPS bulbs, use for the flowering stage of your plant’s life cycle in conjunction with an MH bulb, with the most efficient ratio being 1 HPS for every 1 MH.

10,000 hours.

What are the costs?
Average Cost incl. ballast (need to have specific costs inserted)
400 watt MH lamp – $85 – $120.
400-watt HPS $25 -$40.
400-watt Ballast $175.

-Excellent marijuana lighting for bud production.
-Excellent Spectrum.
-Still the best light source for indoor growth.

-High electricity bill.
-Run at high heat.
-Short life in comparison to others.

Reflector HoodsReflector hood
Reflector hoods make your bulb more efficient as they reflect light back towards the plant. An effective horizontal reflector hood increases the amount of light coverage and brilliance your weed grow lights produce, helping to produce bigger yields. The closer you move the hood to your bulb, the more light it will reflect. This in turn generates more heat which growers need to be careful of as it can cause your plant to suffer from heat burn. . Open-ended hoods dissipate heat quicker as do those made from aluminum. To increase cooling, aim a fan at the light hood to circulate air around the bulb.

Grow Room Reflection
Using reflection helps get light to the lower parts of the plant, increasing your overall bud production and making your grow room more efficient. There are many different types of reflective materials available for your grow room with the best two listed below. For more examples, please view the Grow Room section.
Mylar reflective material
Mylar Reflective Mylar – This is the preferred reflector of choice for most indoor growers as it reflects almost all light from your marijuana lighting when laid flat against the wall. Cover staple or nails with tape to prevent ripping.Flat white paint

Flat White Paint – Contains little or no light-absorbing pigment and therefore reflects a large amount of light. Use a matt texture as it reflects more light.

What is ballast?
Ballast for marijuana lightsBallast is used in conjunction with an HID lighting setup. A ballast is a transformer that alters the electrical current used by your bulb. A smart grower will buy their entire HID system at the same time, including, the lamp, ballast, socket, connecting wiring, and timer. If you do not match the ballast with the bulb, you either run the risk of having inefficient lighting or burnout, which could result in you losing more than your marijuana crop! Ballasts run between 90 – 150°F, so make sure they are not placed on anything flammable.

Bulb Proximity
Plants need around 10,000 lumens for maximum growth and yield. The table below will tell you how far you should be keeping your light bulbs above the plant.
Grow light proximity table

Light Cycles
A light cycle is the amount of light and darkness within a 24-hour period. Throughout its life, your marijuana plant will require different amounts of light depending on what growth stage it has reached. Having your plant on the correct light cycle is important if you’re going to grow good-quality weed. Putting your plant on the wrong cycle can put it under stress resulting in a hermaphrodite plant and small amounts of weak marijuana.
You can use the following table to see what light cycles you should be on for the various stages of your marijuana plant’s life cycle, to help ensure you’re getting the most out of your marijuana grow lights.Marijuana light cycles

Selecting the right marijuana lighting can be a daunting task when setting up your grow room. The information above on marijuana grow lights and hydroponic lighting should provide all the info you need to help grow some sticky green buds.


  1. Hello A.J. Sugalskivitz,
    I dont know where it said 2700k lighting for seedlings, but you are correct a light source nearer to the 6500k spectru would be more suited to seedlings and veg growth.


  2. Hey there. I noticed it said 2700K light for the seedling stage, why is that? From what I’ve always read and heard seedlings need more blue light (6500K) to develop properly.

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Articles

Back to top button
Seraphinite AcceleratorOptimized by Seraphinite Accelerator
Turns on site high speed to be attractive for people and search engines.