What to Consider Before Choosing Grow Lights [Buyers Guidelines]

Last Updated on December 17, 2018

If you decide to grow the plants indoors, you have to ensure they access sufficient light. If you’ve no access to sunlight, this is where grow lights come to rescue.

Grow lights can be used to effectively to grow plants in an indoor setting with little or no sunlight.

Grow lights are available in an incredibly wide amount of prices, watts, type, sizes, and styles. Some may be better or worse for your specific needs. Let’s get into the details.

Let’s get into the details.

(for a complete guide to the different types of grow lights and a discussion of their strengths and weaknesses, check out this article.)

For someone just starting out indoor gardening, hydroponics or aquaponics, buying the correct grow light(s) is not always a simple task.

Before you make a purchase decision, you may want to consider these guidelines to consider before buying grow lights:

There are many factors and properties that need to be considered, but you should also be aware of your growing purposes, location, and other specifics involved.

Following is a list of the most important things you should look for when making your choice.

Before buying any light, You must

  • Consider what you need
  • know the specifications of lights

Know your needs

1. Space Available

Space availability is a vital factor when purchasing lighting as it determines the amount and size of the lamps you need.

A study showed that most people buying lights grow indoor and are limited in space. That’s why Trend of buying hydroponics tower/vertical garden is growing in urban areas.

If you don’t have the space to operate a certain type of grow light, you won’t be able to use it.!

The reality is that different grow light types will require different amounts of spacing in between the bulbs and fixture and the plants. If your plants are too close to the lighting, they may be burned. In other scenarios, they will have a lower yield.

When space is efficiently used with grow lights, vertical farming stacks can also be feasible by creating multiple layers of plant beds and grow lights.

Do get an approximate idea of the space you will need vertically, see the tables below for LED (light emitting diode) and HPS (high-pressure sodium) lighting.

LED approximate lighting distances
Type of LED Grow LightDistance from Plants
1W bulbAt least 12" (30cm)
3W bulbAt least 18" (45cm)
High wattageAt least 30" (76cm or more
HPS / MH approximate lighting distances
Grow LightClosestSunlightFurthest
150W5" (10cm)7" (18cm)11" (28cm)
250W6" (13cm)9" (23cm)13" (33cm)
400W8" (15cm)12" (30cm)19" (48cm)
600W9" (20cm)16" (41cm)25" (64cm)
1000W11" (26cm)21" (53cm)31" (79cm)

2. Easiness of Use and Flexibility

Sometimes you’ll have to adjust the position of your lamps, based on the plant type and growth stage.

Quality LED lamps are efficient, but also easy to use and will let you fine-tune their placement with little effort.

Also, it is important that the wavelength and light intensity is adjustable as well.

Look for products that are easy to maintain and ready to use straight out of the packaging.

3. Plant Growing Space

It is very important that all of your plants are exposed to light.

You need to measure the exact size of your garden.

Then you need to find out the lighting area size of the lamps you’re considering in order to determine the exact number you need.

The general guideline most growers use is that you need 32 watts of actual power per square foot if you’re growing high-light plants like tomatoes.

Low-light plants like lettuce need somewhere between 11 and 18 watts per square foot.

4. Electricity Output & Consumption and Your Budget

Your LED grow lights will have to operate for at least 10-11 hours each day, which in turn will lead to increased electricity bills.

Making an informed choice and reading the detailed product description can save you troubles in the future, therefore you should always check how many units is the total output.

The options go up to 1,000W but you shouldn’t settle for anything less than 300W.

Have in mind that the higher output helps compensate for any wattage loss.

Know the unit economics

Awareness of the cost per unit area required to light your crops is a good way to compare different grow lights and prices.

Examples for comparison:

  • An $89 T5 fluorescent 2-foot 4-tube system costs approximately $0.29 per sq inch of coverage (~304 sq inch coverage).
  • $35 LED light with $0.24 per sq inch of coverage
  • $36 LED light with $0.25 per sq inch of coverage

Generally speaking, a LED provides more value and lumens in less wattage

A 250 watts LED Grow Light provides same value of light as a 400-watt HPS, though it consumes less than half the power (180w ±).

5. Safety

Not all grow lights have the same safety risks. Two key areas to evaluate with grow light safety are

  1. How fragile the light is
  2. The materials that are present in the light itself.

In both of these categories, LEDs have a clear advantage. Even in household growing projects where pets or children may be disturbing the lights, LEDs are much less likely to break when knocked down or jostled, due to the small size of the diodes and the way they are situated in the fixture.

Other lighting systems like fluorescent tubes and HPS lighting can be very fragile and will shatter or even explode if they are knocked over with enough force.

Are broken fluorescent bulbs dangerous?

Mercury is present in fluorescent lighting. However, mercury released from a broken fluorescent lamp is unlikely to cause health effects because its amount is so small that the vapor is rapidly diluted in air. If you break a fluorescent lamp, promptly clean it up to avoid spreading broken glass and other debris.

One extra consideration: HPS, Metal Halide, and even Fluorescent bulbs give off a significant amount of heat. If you are not sure you have the proper counteractive measures to mitigate this heat, not only will your plants suffer, but you may be creating a fire hazard.

6. Consider What You Are Growing

Some plants need more light. (vegetable & flowering plants)

& some plants can even thrive in shade/dim light (mostly ornamental)

The lighting you choose must be suitable for the type of plants you’re growing. All LED lights will do the job to some extent, but certain models are made to address specific plant needs, as plants need different kinds of wavelengths during each growth stage.

For example, if you are growing heavy crops like tomatoes, you will need a different light to maximize its growth than if you were growing flowers.

Also, do you need lights only for vegetative cycles, flowering or is it a complete growing process?

Know the key grow light specs

1. LED vs Fluorescent vs HPS

You have to choose from 3 types of grow lights: fluorescent lights (CFL), high-pressure sodium lights (HPS), and light-emitting diodes (LED).

LEDs are the most efficient grow lights with a lot of options and have a higher upfront cost than CFL. LEDs require less wattage than CFL for the same amount of light.

CFLs are widely available at most retail stores and have a low upfront cost but they are less efficient than LED.

High-pressure sodium lights (HPS) may be difficult to manage for beginners because of the setup process and ventilation and heating issues that HPS presents.

2. Intensity

Consider the light intensity of the grow lights you want to purchase.

Lumens are a measure of a light’s intensity or brightness, however, this measurement is designed to quantify human visibility, not plant visibility.

The metric to consider for grow light intensity is Watts (W). Generally speaking, the higher the watts, the better.

Light wattage is a key indicator of light pricing, so managing the cost-wattage trade-off for your first grow light system is important.

Check our post about Best Grow Lights Available: 1000w, 600w, 400w, 250w, 150w 

The fluorescent bulbs have most enhanced high light intensity.

3. Light Color and Spectrum

Plants convert light energy into plant energy via photosynthesis.

There are two primary compounds that achieve photosynthesis: Chlorophyll A, and Chlorophyll B.

These compounds absorb blue and red light, while nearly all other spectra are reflected away from the plant and into the nether.

“Red” and “Blue” light spectra are ideal for plant growth, with red being associated more with the flowering stage of plant growth and blue with the vegetative stage.

There is a term called the “absorption peak” which is the point at which Chlorophyll converts light energy into plant energy the most efficiently.

These absorption rises are measured by wavelength (nanometers/nm).

Grow Lights colors and photosynthesis absorption
Photosynthesis depends on the absorption of light by pigments in the leaves of plants. The most important of these is chlorophyll-a

LEDs have edge over HID and fluorescent light in this scenario.

L.E.D’s (LED grow lights) are light sources that emit narrow wavelengths of light and can be tailored to nearly any nm that you as a grower desire.

By using L.E.D’s at the same nm as each of the absorption points for Chlorophyll, high-end LED grow lights (like the Pro-Grow series we use) plants can convert light energy into plant energy much more efficiently than HIDs,

A Pro-Grow 260 LED lamp is easily comparable to a 400-watt HPS, though it consumes less than half the power (180w ±).

Hence, A powerful full spectrum LED grow light enables you to cater to the plant’s specific needs by providing the proper photosynthetically active radiation values.

4. Size of the Bulb

If you’re going to use fluorescent lights, You should check the size of the bulb tube. The standard bulb tube size is T-12 ( can suit various needs).

The standard bulb tube size is T-12 ( can suit various needs). However, the best grow lights for plants have sizes ranging from T-5 to T-8. These bulbs are quite efficient.

If you are not so sure of the sizes that can best suit your plants’ requirements, request for advice from the seller and let him help you choose the best bulbs.

5. Automatic Timers and Light Duration

No plant requires 24-hour sunlight.! In fact, all sun and no shade make Plant a dull boy. Also, you may not want your grow light to die off earlier by keeping it on for 24/7.

Dark hours are equally important in plants’ vegetative growth like flowering and fruit production.

However, Day and Night Cycle varies largely from species to species. Most vegetables and plants require long duration exposure of high light intensity (usually fourteen to eighteen hours a day) to flourish.

So, You must keep the plant exposed to sufficient light during the day to facilitate photosynthesis.

Also, Ensure the plants are kept in the dark at night to allow tissues to rest.

Necessarily, You may want to use automatic timers to automatically adjust from light to darkness and darkness to light, consistently.

Choose one which comes with automatic timers..!

6. Heat and grow lights

One of the major components of indoor growing is the temperature. Generally speaking, most types of grow lights will generate heat.

This is one of the most important things when choosing grow lights, as it contributes to two main factors – plant protection and durability.

The lights are in constant proximity to the plants and having low heat output guarantees that there won’t be any damage but also enables for a smaller distance between the lamp and the plant.

A light with higher heat output would burn out more quickly and will need to be replaced sooner.

High-Pressure Sodium / Metal Halide: will generate significant heat, must use in unison with fans or other tools for ventilation.

Fluorescent: will not generate as much heat as other grow lighting options, but still significant.

LEDs: extremely minimal heat, in most cases, you will not need to factor in any temperature differences if you are using LED grow lights.

Tip: Most content online will discuss the downsides of heat, the preventative measures required with grow lights that generate heat, and how to prevent overheating. However, for many indoor growers, the risk of temperature becoming too low can be decreased by using a grow light that generates some heat.

Keep in mind that just because a grow light adds warmth, you will likely need to take other steps if you are growing in a particularly cold room (< 20 C or 70 F). Some options include tenting for insulation or heating pads.

7. Price of Grow Light

One of the most important metrics to consider when buying your first grow light is the price of the grow light.

The good news for grow lights is this: there are a lot of options at all price points.

$: CFL bulbs: can be found on Amazon for less than 10 USD

$$: T5, T8, T12 fluorescent: good value for less than 100 USD. A 4 tube T5 grow light system can generate multiple hundreds of dollars worth of produce in a year (1-2 year payback period with all other costs factored in beside lighting).

$$$: LED and High Pressure Sodium (small sizes): most LED solutions will be on the pricier side relative to fluorescent, if you are going to spend on LED’s, your best option is to invest in a light from a well-established LED vendor (full explanation in the next section “Vendor Quality”)

$$$$: Most heavy-duty commercial style systems will involve high-pressure sodium/metal halide (collectively referred to as HID or high-intensity discharge) and high-priced options are increasingly now appearing for LED systems. These systems will range in the thousands of dollars+ (USD) and will often be part of larger systems involving grow tents, grow “boxes”, air filters, fans, controlled environment features, etc.

8. Vendor Quality & Brand Reputation

There are many different brands on the market and each one provides slightly different products. This makes the choice all the more difficult, considering that not all options are of equal quality.

In case you’re wondering between different light choices where price and appearance are almost equal, taking a look at the brand can provide the answer. As in other fields, a company with a good reputation, long history, and extensive research and development efforts is more likely to have a good product.

Warranty and Return Policy

LED lights should last about 10 years under normal usage, so you should be wary of warranties that cover less than that. It is usually a sign of bad quality and cheap materials.

Most manufacturers also provide a guarantee on the parts of the light, including a free return shipment policy. Some parts of LED lights function independently, so if you’re waiting for a spare to arrive your light can still do its job.

There are over 57,000 results on Amazon.com for the search term “grow lights”. This vast array of options is not equal as far as quality goes.

For grow lights, ratings, and reviews on sites like Amazon, Alibaba, or even niche sites for grow lights may not guarantee you are receiving the product quality you paid for.

How so?

With grow lights, the technical specs in reality often are not as advertised, even for a brand new product.

The true wattage of brand new LED grow lights varied wildly (one light had 34.2% lower wattage than advertised).

When you are paying for grow lights, a lot of what you are paying for is wattage, so this is a serious risk to consider when buying grow lights. This sort of issue could cost you hundreds if not thousands of dollars, and, most importantly, time, if undetected.

Solution: We have shortlisted the trusted and most used brands in our post about Best LED Grow Lights

9. Scalability

If you’re planning on starting with a small growing operation but think you may eventually work up to selling your crop to restaurants, you need to keep in mind the scalability of the grow lights you are purchasing.

For example, fluorescent grow lights like T5, T8, and even T12 have been demonstrated to perform well in stacked arrangements.

Other questions to consider:

How will the power requirements of your grow lights change at scale?

How will the unit economic cost change?

Will I be able to effectively grow at scale with this type of grow light only?

Common grow light accessories

Often times a grow light will be the only part of the “package” or “kit” you are purchasing. Here are other potential additions besides the grow light that you should know about:

Ballast/fixture: Grow light systems require an electrical component called a ballast to regulate the power supply in the grow light. if you are buying just a bulb, of course, you will also need a ballast. This is a necessary component for lights. ballasts can be purchased independently from grow lights but grow lights can also have the ballasts incorporated into the unit.

Grow Tents: grow tents are another feature mainly seen with more expensive systems. Tip: It’s worth noting that many of the benefits of a grow tent that help create a more controlled growing environment can be replicated cheaply DIY (not all the benefits).

Grow Room Sunglasses: Protect your eyes from UV rays indoors too when you’re running a full-spectrum LED light.

Light meterMaybe you think only advanced growers use them, but you can use one, too. Then when you’re advanced, you’ll already know how.


Here are a couple more tips for you, if you’re still looking for more information. we will update this list and add on tips in the future:

  • Fundamentally, all grow lights are replicating the sun. however grow lights are not as powerful as the sun, plan to run grow lights for 12-18 hours per day. Timers can help you manage this cycle.
  • Fluorescent lights will not typically have a color temperature / Kelvin rating listed on packaging in normal stores, instead, they will be more loosely categorized into categories like “warm glow”, “soft white”, “bright white”, “daylight” and “cool white” that each correspond to ratings
  • When looking for fixtures/ballasts look for ones that have reflectors. Reflectors will help you significantly increase the efficiency of your lights. As an example, fluorescent lights emit light in all directions with equal intensity. Without a reflector, up to half of your light will not be shining where it needs to shine: on your crops.
  • Roughly 2/3 of your grow light expense should be the fixture/ballast and 1/3 of the expense should be the bulbs. other one time costs may be involved in things like mounting.
  • A reasonable payback period for a non-commercial grow lighting system should be around 1-3 years

Have you bought any Grow light or planning to buy? Tell us in your comment about your experience and thoughts


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