how to buy grow lights?

Published by Cretivity 2021-08-02

how to buy grow lights?


With the rise of indoor gardening, there is no doubt that grow lights are becoming more and more popular every day. However, due to the large variety, quality, wattage, manufacturer, terminology, and planting space calculations, it is absolutely difficult to find and buy the perfect planting lamp that suits your needs. This is especially true if you are a beginner.


If you want to know where to buy grow lights and which grow lights are best for your needs, this article will simplify everything, including true wattage, coverage calculation, grow lights type, efficiency, warranty, and buy grow lights The best location.

If you are an experienced plant light user and only need the best plant light recommendations, please click here to jump to our LED grow lights list.

If you are a beginner, then I suggest you continue to read the complete grow light buying guide, and then check our best grow light comparison table to choose yours.


1. What are the different types of plant growth lights?


If you are a beginner, this may be the first question you think of. There are 3 different types of grow lights on the market.


●Fluorescent grow lights
●HID (High-Intensity Discharge) grow lights
LED (Light Emitting Diode) Grow Lights


2. What are the important light colors for plant growth?


(1) Light of blue wavelength-it promotes leaf growth (helps to lengthen cells)
(2) Red wavelength light-it promotes flowering and fruiting
(3) Green wavelength light plants do not absorb green light and reflect it.
(4) Other colors-less important, but plants prefer most colors.


The most important light colors for growing plants are blue and red (learn more). Please keep this in mind, it will help you better understand the rest of the article.


3. What types of plants can I grow with plant lights?


Basically, you can divide plants into two different categories
(1) Plants with low light requirements, such as basil, thyme, other herbs, lettuce, green leafy vegetables, etc.
(2) Plants that require high light, such as medicinal plants, peppers, tomatoes, cucumbers, citrus, most vegetables, etc.

You can use grow lights to grow plants with low light and high light requirements.


4. What are the different types of plant lights available?


4.1 Fluorescent plant growth lights


Fluorescent grow light


If you are growing several kinds of plants, please use fluorescent lights as a hobby or just for fun people's attention! Their output will be very low, so large-scale growth will not be cost-effective. Fluorescent lights are used for vegetables and cloning, but if this is not your purpose, please skip it.


4.1.1 Types of fluorescent plant lights


●CFL (Compact Fluorescent Lamp)——Small size, suitable for most standard household sockets, and can be used for a few plants.
●T5 (tube light)-can support more plants and provide blue spectrum light, which is cool enough to facilitate flowering.
●T8, T12 (tube lamp)——similar to T5, but with different thickness. Not as efficient as T5.


4.1.2) Reasons why fluorescent plant growth lights should not be used


● Low light intensity. Without sufficient light intensity to support large-scale planting and growth, you must keep your plants short.
● Not enough to bloom.
● In the long run, it is not cost-effective or efficient.
● Each bulb or tube needs a separate socket, which is difficult to expand and maintain.
● Fluorescent lights need to be very close to the plants. As the plants grow, you need to adjust the height regularly.
● High heat is easy to burn plants, it needs to be equipped with external fans to cool down, which is costly.


4.1.3 Scenes where fluorescent plant grow lights can be used


● Fluorescent grow lights can be used for cloning or vegetable planting, especially where the roof is too low. They generate less heat and can be hung close to plants without harming them.
● If your budget is very tight, you can use them. They are the cheapest of grow lights.
● If you want to get something quickly, you can buy fluorescent grow lights at any hardware store, Wal-Mart, etc. Most of them are suitable for any standard socket.
● Fluorescent CFL or T5 tubes can be used to support succulents because they do not require much light.


4.1.4 How far should the plant be from fluorescent lights?


Fluorescent lights should be suspended within 12 inches of the top of the plant. They generate the least amount of heat and should be hung as close to the plants as possible without burning them.


Palm test to know how far to hang the growth light
An easy way to determine the perfect distance is to place your palm on top of the plant for a few minutes. If the heat is tolerable but warm, you can keep it at that distance. If it is not warm enough, try turning the light down and test again. If it is too hot, try to increase the light and test again to find the best position.


4.1.5 How many fluorescent lamps do I need?


The number of bulbs is not important, usually, your goal should be 60 watts of vegetables per square foot and 100 watts of flowering power. This is actual watts, not "equivalent" watts. Place enough light to ensure that there are no shadows on the plants.


4.1.6 Advantages and disadvantages of fluorescent plant lights



● Lower cost, cheaper than any other plant grow lights
●Can be purchased online or at any local hardware store
● Need less space
● Low electricity cost
● Low heat



● Low efficiency (output per watt)
● Only suitable for a few plants
● The plants must be kept short
● Need to constantly adjust the height
● Each bulb requires a separate socket


4.1.7 What should I pay attention to when buying fluorescent plant lights?


● Buy low-Kelvin and high-Kelvin lamps (bulbs or tubes).
● Use 5500K to 6500K (cold/blue) light to support leaf growth.
● Use 2700K to 3000K (warm/red) light to support flowering and fruiting.
●High output (HO) bulbs are recommended
●If you want to buy tubes, please choose T5 because they are more effective than T8 and T12.


4.2 HID Plant Growth Lights


HID Plant Growth Light


You can use HID (High-Intensity Discharge) grow lights to grow large indoor gardens or businesses. It is cheaper than LED. The cost of a complete HID planting kit with HPS bulbs, MH bulbs, hangers, ballasts, timers, and reflectors is lower than that of LED planting kits.


4.2.1 Who should use HID plant growth lights?


Anyone who wants to run a business with an indoor garden can use the HID planting kit. HID is famous for growing vegetables, such as kitchen herbs, lettuce, peppers, tomatoes, spinach, etc.


4.2.2 Types of HID bulbs


There are 2 types of HID bulbs on the market-MH and HPS.
MH (metal halide) bulb emits a strong blue spectrum, which is beneficial to the growth stage of the plant but has little effect on the flowering stage

HPS (High-Pressure Sodium) bulbs-emit a strong red spectrum, which is good for the flowering stage, but too much makes the plant weak and tall during the vegetative stage


4.2.3 Should I use a dual-ended HID lamp or a single-ended HID lamp?


Both MH and HPS bulbs have 2 variants-single-ended (SE) and double-ended (DE). As the name suggests, the SE bulb is connected from one end, and the DE bulb is connected from both ends and ignites.

Tests have shown that DE bulbs still maintain 90% of their lumens after 10,000 hours, while SE bulbs drop to 90% of their lumens after only 4000 hours. However, double-ended HID bulbs are more expensive than single-ended bulbs. For this reason, many growers still use high-quality single-ended bulbs.


4.2.4 Several disadvantages of using HID plant growth lights


Compared with any other grow lights, it emits a lot of heat.
An additional cooling system is required to dissipate heat.
Ideally, you need to use both MH and HPS bulbs to get a healthy harvest.
Each light bulb needs a socket, ballast, and reflector.
The bulb must be replaced more frequently.
The ceiling needs to be high enough. Due to the high heat output, the HID system must be hung far away from the plants.
In the long run, it is not as cost-effective as LED.
HID has a high failure rate.


4.2.5 Reasons for using HID plant growth lights


If your budget is limited, then you can use HID lights. (Cheaper than LED).
The HID system provides deep light penetration and high throughput (HPS).
If you are located in a colder area and can benefit from the extra heat generated by HID.
● The HID system provides deep light transmission and good coverage. If your initial budget is low, please choose HID.


4.2.6 How far should the plant be from HID lights?


It is important to hang the MH or HPS grow light far enough above the plant. The distance depends on the wattage of the bulb covering the area. The higher the wattage per square foot area, the farther the light should be hung.

You can feel the heat with the palm of your hand and adjust the height accordingly, just like the fluorescent light I mentioned. In addition, please check the table below to better understand the changing distance of the HID lamp.


4.2.7 How many HID lights or watts do I need?


A 150-watt HID bulb can cover a 2'x2' main area. The higher the wattage, the larger the area it can cover. I have listed the wattage and coverage area and the distance to hang the light above the plant in order to give you a better idea.



Coverage area

Total square foot

Distance from plants

150 watt

2' x 2'

4 sq ft

8 - 12 inches

250 watt

2.5' x 2.5'

5 sq ft

10 - 14 inches

400 watt

3' x 3'

9 sq ft

12 - 18 inches

600 watt

4' x 4'

16 sq ft

14 - 25 inches

1000 watt

5' x 5'

25 sq ft

16 - 30 inches


Therefore, you can buy 100 1000 watt lamps or 250 400 watts HID plant growth lamps to cover your area. You can also mix them to meet the 100,000-watt requirement.


4.2.8) Advantages and disadvantages of HID grow lights



Lower initial investment
Many successful growers use HID
● Deep light transmission
Good coverage



Higher electricity bills
High heat output
The light bulb disappears faster
Need to hang above the plant


4.2.9 What should I pay attention to when buying HID plant growth lights?


Bulb type

Buy MH and HPS bulbs. Replace some MH with HPS during flowering. Or use both at the same time for best results. If you have a tight budget and only want to buy one type of bulb, then buy an HPS bulb.



Use light bulbs from 250 watts to 1000 watts, but 600-watt bulbs are the best in terms of efficiency. Please note that a 1000 watt bulb is very hot when it is running, and you need to have enough cooling to support it.


Single-ended or double-ended

Although a double-ended bulb is more efficient than a single-ended bulb, it is also much more expensive. I suggest you use a single-ended device. In addition, make sure you have a good cooling system in the planting room.


Complete kit

Purchase an HID kit with a complete kit (bulb, ballast, reflector, hanger, etc.). Easier to set up.



Your planting room or planting tent should be well ventilated or have enough cooling to run HID lights.



Do not use MH bulbs only if you are growing plants that will bloom or bear fruit. Using only MH bulbs will not produce much output.

On the other hand, if you are a new grower and/or are cautious about your operating costs, I suggest you skip HID and use LED grow lights, assuming you have a sufficient budget.


4.3 LED grow lights


LED grow lights


If you plan to run a mature indoor garden, LED grow lights are the most efficient and cost-effective. Although this latest plant light technology has a higher initial investment, it can obviously make up for your electricity bill and service life.

LED grow lights can provide full-spectrum (simulated sunlight) colors or important red and blue colors. If used properly, these lights can certainly support large indoor planting houses.


4.3.1 Some disadvantages of LED grow lights


- Compared with similar HID growth light settings, the initial cost is higher.

- LEDs generate less heat, so you may need to provide additional heating for the planting room if you are in a colder area.

- If you switch from the HID setting, there will be a learning curve, and when you learn, your output may be affected.

-There are too many low-quality options on the market, and it is difficult to find and choose the best.


4.3.2 Good reasons for using LED plant growth lights


– Lower operating costs than HID in terms of power and service life.
– Very easy to install, most devices are basically plug-ins and players.

– You do not need additional equipment. For example, separate reflectors, ballasts, etc.

– Compared with HID, LED is more efficient and consumes much less power with the same output.

– LED lights generate much less heat than HID lights, operate at a lower temperature, and require less cooling.

– LED light do not contain any mercury content that is harmful to the environment.

– High-quality LEDs give you more control over the color spectrum. For example, during the vegetable period, you can turn off the red light and keep the blue light, which is mainly needed during the vegetable period.

– LEDs promote better growth and produce high yields when used correctly.


4.3.3 How far should the plant be from LED lights?


Generally, you should place LED lights between 12 and 30 inches above the plant. As mentioned above, use the palm method to test the heat.


4.3.4 LED wattage-the difference between theoretical wattage and real wattage?


Most manufacturers use theoretical wattage instead of actual wattage to advertise their LED grow lights, which may mislead most people. You may feel very confused, buying the wrong LED settings, and eventually losing money and gains. Therefore, it is very important for you to clearly understand this when buying LED grow lights.


(1) What is the theoretical wattage of the LED?

LED is composed of a group of many small diodes. The theoretical wattage is the "maximum wattage" of all diode combinations. For example, an LED luminaire composed of 100 diodes rated at 3 watts is usually advertised as 300 watts (100 x 3)


(2) What is the real power of the LED?

In fact, in order to prevent the diode from burning out and prolong its service life, the diode will never run at full power. Therefore, taking the example above as an example, the power of a single diode maybe only 2.5 watts (2.5 x 100), so you can only get 250 watts of true power from the fixture.

Therefore, be sure to check the product description carefully and find the true wattage. When buying an LED grow light, please consider the actual wattage. Because this is very close to what you actually get in real life.


4.3.5 How many LED lights or wattage do I need?


First, you need to measure your planting space in square feet if you have not done so already. The watt calculations we will perform here are based on area rather than the number of plants.

However, depending on the type of plants you plant and how much space you need, you can also easily calculate how many such plants can be planted in that space.



When allocating space for your plants, remember how much space each plant will take up when it grows up.

For plants that require high light, LEDs need 30 to 40 real watts to cover 1 square foot of space.

For plants that require low light, it takes approximately 15 to 20 watts to cover 1 square foot of space.


Note: For this chart, the calculation of the number of plants assumes that each plant occupies 2'x2' or 4 square feet of space.



Total square foot

Real power (high plants)

Real power (low plants)

Plant quantity (4 square feet)

1' x 1'

1 sq ft

30 - 40 Watt

15 - 20 Watt


2' x 2'

4 sq ft

120 - 160 Watt

60 - 80 Watt


2' x 3'

6 sq ft

180 - 240 Watt

90 - 120 Watt


4' x 4'

16 sq ft

480 - 640 Watt

240 - 320 Watt


5' x 5'

25 sq ft

750 - 1000 Watt

375 - 500 Watt


10' x 10'

100 sq ft

3000 - 4000 Watt

1500 - 2000 Watt


20' x 200'

400 sq ft

12000 - 16000 Watt

6000 - 8000 Watt


25' x 10'

250 sq ft

7500 - 10000 Watt

3750 - 5000 Watt


50' x 10'

500 sq ft

15000 - 20000 Watt

7500 - 10000 Watt


100' x 100'

1000 sq ft

30000 - 40000 Watt

15000 - 20000 Watt



 True wattage

Please note that all the above calculations are done using real or actual LED wattage, not the theoretical wattage clearly explained above.


4.3.5 Advantages and disadvantages of LED plant lights



●Efficiency is about 38% higher than HID
● Reduce electricity bills
● Longer light life
● Lower heat emissions
● Easy installation
● All-in-one lamps (no need for separate reflectors or ballasts)
● High-quality LEDs can better control the spectrum
● Higher output if used properly



● The initial cost is higher than other grow lights
● Too many choices, it is difficult to choose high-quality lamps
● Full-spectrum LED can simulate natural light or sunlight
● Additional heating may be required in colder areas
● If you switch from HID, you must go through a learning curve


4.3.6 What should I pay attention to when buying LED plant lights?


Real/actual watts

Check the specifications carefully and find the actual wattage, not the theoretical wattage in the advertisement.


Full-spectrum or multicolor

Both full-spectrum LEDs and color LEDs can support plants at all growth stages. However, I recommend using full-spectrum LEDs for best results. They are more expensive but are best suited for all growth stages. If it includes infrared and/or ultraviolet, so much the better.

There are 2 options for full spectrum LED, white LED and multi-color LED. Full-spectrum white LEDs are closer to natural sunlight.

If you move the plants higher but the light intensity or PAR value decreases, the coverage area will increase. If you move the lights closer, PAR will increase and coverage will decrease.

If you move the plants higher but the light intensity or PAR value decreases, the coverage area will increase. 

If you move the lights closer, PAR will increase and coverage will decrease.

The coverage area listed on most LED lights indicates that it can provide sufficient light intensity for flowering and fruiting. 

However, the PAR values ​​listed by many manufacturers can be misleading, and some manufacturers list the PAR in the center of the area that is always higher than the rest of the surrounding area. Your best choice is to buy from a quality manufacturer.


Larger or smaller lamps

It is better to buy multiple smaller LED lamps than to buy smaller ones. Buy two types of lamps and mix them together to achieve your total wattage/space requirements. This way your plants will get light from more directions.


Warranty and manufacturer

Make sure your LED comes with a warranty. And buy grow lights from well-known manufacturers. Many new plant light companies came and then quickly closed down. If the company does not exist, there is no warranty claim. So remember this too.



If you don't see all the LED lights are on, please don't think your LED lights are broken. Check the specifications first. Many LED lamps contain UV and IR lamps. You will not see these lamps light up because they are invisible to the human eye.



Many growers like to change lights at different growth stages. For example, more blue in the vegetative phase and redder in the flowering and fruiting phases. I recommend using the same lights at all stages, as this will avoid shocking the plants and increase yields.


If you do not have any experience in planting with HID lights, I suggest that you should start with LED planting lights. Because LEDs will become more cost-effective and cheaper, it is the future of indoor gardening. If you start with HID and then switch to LEDs, it will take a while to get used to.


On the other hand, if you are already using HID lights for planting, you can continue to use HPS/MS lights. Because growing with LED is different from growing with HID. If you switch to LED, you will go through a learning process.


5) final words

Whether we like it or not, we all have our own budget constraints. Therefore, through the above options, you can make a wise choice according to your budget and needs, but under the current planting mode, in the future plant lighting fixtures, LED plant growth lights will replace all lighting equipment (learn more).

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