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How Many CFLs Per Plant: A Beginner’s Guide to Growing With CFLs 2021

Have you ever thought about how many CFLs per plant for your grow area? Can those CFLs bring enough energy comparable to natural sunlight?

These are some of the questions a person faces when investing in indoor planting or farming.

Sunlight is the ideal source of energy for photosynthesis, but for some spaces and areas that are highly urbanized and commercialize, only technology can provide alternative solutions when natural sunlight is unfeasible.

A Complete Guide To Newbie: How Many CFLs Per Plant You Should Use

Grow Area

In raising plants and farming, the term ‘grow area’ refers to space where the plants being embedded are subject to the light for controlled growth. It also depends on the type of plant being raised.

If plants grow upright like tomato plants, then the growing area can be relatively narrow but needs more room vertically.

However, if plants grow widely like bush plants, then the growing area can be relatively wide but don’t need more room vertically.

The growing area will always be dependent on the ideal characteristics of the plant to be raised and the area you have available.

Now that the control space is being defined, we can now tackle on how a plant grows.

It is already basic knowledge that plants need growing space, water, and sunlight to flourish. Out of the plants’ needs, only sunlight is impossible to be provided.

Since it is a force of nature, we resort to alternative options like grow lights. The most important measurement to consider for grow lights is PAR.


PAR, or Photosynthetically Active Radiation, can be defined in layman’s term as the measurement unit for the light source’s energy distribution to the growing area.

The energy produced by a light source can either nourish the plant or damage it.

Therefore, there is enough amount of energy in order for the plant to absorb it through radiation and convert it into chemical energy through a process called photosynthesis.

For an easy understanding of the term, it is better if a PAR sensor is used. It measures the amount of power the grow light is emitting.

Please do note that power and energy are separate in definition but are directly proportional in quantity.

Direct Connection of Grow Area and PAR

Grow Area and PAR are directly connected to each other. If you have a wider grow area and a single light source, you need to measure the PAR using a quantum sensor to have comparable data.

That data can help you decide at what height will you place the light source in order to maximize the growth of your selected plant.

If a sensor can be too much of an investment, you can check out other research and experiments done by others that are readily available online.

CFLs Usage is Growing


As an alternative to the absence of sunlight, grow lights are being used.

One of the types of grows lights that are popularly used is ‘CFLs’. CFL, or Compact Fluorescent Light, is the traditional fluorescent lights being molded into a bulb-shape with the purpose of replacing the convenient but inefficient incandescent bulbs.

These types of lights, unlike their ‘original’ form, are fast reacting and do not usually require other elements like a starter to perform, hence the term ‘compact’.

Difference Between Other Light Sources

CFLs are intended to replace the incandescent bulbs because of the latter’s inefficiency. The electrical energy is only converted mostly to heat instead of light.

If you notice on some tall street light posts, the bulbs used are sodium lights. They are better than incandescent but only suitable for very large coverage area like the streets, Majority of the electrical energy from sodium lights are converted to heat.

The leading light source of this modern age is LED. Although it is so much better in almost all aspects, CFLs remain usable today because of its lower initial cost.

It is still preferable as grow lights since the light emitted is the needed wavelength for photosynthesis.

CFL Bulbs Capacity

The standard CFL, if used as fixtures, can last from 6,000 hours to 15,000 hours.

Typically, they emit the same amount of lumens, a measure of light power perceived by the human eye, with the incandescent bulb but needed only 60 – 75% lesser electrical power.

However, as you constantly switch on and off for just a short interval of seconds, the lifespan of CFL will be reduced.

As a grow light, there are CFLs made for that purpose alone, meaning they are meant to perform longer ‘switched-on’ conditions.

Common CFL grows lights are available at 125 W, 200 W, 250 W, and 300 W.

CFLs are available from the warm red spectrum, which is recommended for growing flowers, up to the cool blue spectrum, which is recommended for growing vegetation.

In case you are not familiar, the colors represent the wavelengths of the light being emitted.

As the wattage goes higher, the measurement ‘lumens per watt’ slightly decreases. Please do note that the unit of measurement important in growing is PAR, not lumens.

They are directly proportional since both involve the performance of the light source, but when purchasing them, the manufacturers only indicate the wattage and lumens. Only through a specialized sensor can PAR be measured.

CFLs Investment

So, how many CFLs are needed per plant? Practically, only one that you can afford is enough per plant. However, that can be improved with proper design and planning.

You can have one CFL that is powerful enough to illuminate several plants. Proper steps are to be considered so that an investment like this can be rewarding.

Set-Up Procedure of How Many CFLs Per Plant

Step 1: Growing Design Set-up

Assuming that all tools and materials are available in your area and you can afford them, you have to take into consideration the specifications of your grow area; the plant area is one of them.

You have to classify if the plant produces flowers, vegetables, or even both. By doing this, you know what type of CFL bulb you need to buy.

Another thing to consider is the energy coverage. How many plants you want to grow in a single grow room will determine how many lights you need.

If you have a wider area, a single light bulb might not be enough. So, you have to decide the number of bulbs in proportion to the area of coverage.

While considering the coverage, there is a term called ‘crossover’. It is the area where the light from two sources intersects.

With the use of a PAR sensor, you can design through proper placement of the grow lights wherein the crossover compensates the lack of energy needed when a single light source was used.

Lastly, your grow room must have the necessary distance in which the grow light can illuminate the plant.

Even if your room had a low ceiling, every bit of distance between your grow light to the plant matters.

Your light holders have to be situated wherein it can be stable and also be adjustable.

The closer the grow light to the plant, the more the energy is concentrated at the center. It can cause damage especially for plants growing vertically or upright.

The farther the grow light is from the plant, the lesser energy is concentrated in the middle and the more is being distributed around.

However, there is what most call, a ‘sweet spot’, in which balance is achieved.

It is the distance in which the light energy is not that concentrated yet enough also for the outer regions to be covered significantly. This can be easily achieved through a PAR sensor.

Step 2: Bulb Selection

The criteria of the selection of bulbs can be the wattage needed and the illumination required.

These can be dependent on the type of plant being grown and the pace of the products, be it flowers, fruits, legumes, etc., needed to harvest.

With that in mind, research can help you maximize your options in choosing the right bulb.

In case you cannot afford to buy the specialized CFLs, regular CFLs can still be applicable since the wavelengths of the light they emit are appropriate for the photosynthesis. You have to scale the capacity of the regular CFLs to the selected specialized CFLs.

You can even convert a high powered specialized CFL into 2 regular CFLs with total equivalent wattage. Remember to take note of the crossover, which can easily be monitored through sensors.

Step 3: Cost Consideration

For an investment such as this, whether it is for hobby or for livelihood, costs must be carefully considered. Costs can be categorized into 2: Initial cost and Operation cost.

Initial cost refers to the things or methodologies you have to purchase and establish in order to start running the system.

For growing plants, the price of grow lights is considered the initial cost.

The price varies depending on the bulb’s specifications. However, it is also worth noting that the bulbs have lifespans and needed to be replaced after. Therefore, a spare should definitely be considered in the budget.

Operation cost refers to the things or methodologies you purchase and maintain in order to keep the system running. In this case, the electricity utilized is a good example of an operating cost.

The electric bill is proportional to the amount of electrical energy used by the grow lights. For proper computation, your bill has a breakdown, or you can use an online calculator for convenience.

The number of hours needed for the CFLs or any grows light can be as long as 24 hours and as short as the amount of time the sun is visible in the skies.

The time definitely mattered since you will be hastening the ‘usual’ process of the plant growth.

It can be a good experiment whether having the grow lights switched on for 24 hours will yield twice the results of a plant under the sunlight conditions or not.

Step 4:  Supplier Consideration

Regular CFLs are readily available even at a convenience store. For specialized CFLs, it is only available in a hardware shop where you can find them. You can do a price comparison and take note of the warranty offered and the abundance of supply.

An appropriate warranty means the period offer is long enough for the kinks to be noticeable. If the product is from a very trusted brand, then a short warranty period might be what you need after all.

The abundance of supply means that spare parts or items ready to be replaced are of no shortage.

Additionally, you will be having the convenience of deciding to expand your grow room, for you will be having many options of available grow lights.

Do-It-Yourself (DIY) Troubleshooting and Solutions

Troubleshooting a problem involving electricity can be relatively easy with a little knowledge and the proper tools. A multitester can check in what part of the system have defects.

If a CFL is found problematic, the quickest way to solve it is replacing it with a new one since its compactness limits the possibility of easy repair.

Sometimes, even when replacing, the new CFL might break if another defect is causing the problem and the bulb becomes the outlet.

If such a situation happens, you have to make sure all the elements of the system are compatible when interconnected.

Compatibility involves the proper voltage rating, the fuse ratings that do not impede the elements’ current ratings and the materials used as the wire connectors are capable of handling the power to be delivered.

Issues and Benefits


So far, CFLs continue to serve their purpose well. Nevertheless, the lifespan of this type of light bulb can be a problem of waste management. Ideally, you have to replace the bulb every year.

With the emergence and continuous development of LEDs and the outbreak of new optic technologies, soon the CFLs will be a thing of the past.


Since CFLs are discovered first than LEDs, they are relatively cheaper. They are also more abundant as of this period of time but soon they won’t be when manufacturers start lessening their production.

CFLs still are appropriate grow lights for they are ‘photosynthesis-friendly’. Some LEDs can be hurting to the eyes although soon enough, there will never be a problem an LED can encounter.


The indoor plantation can be more complicated than outdoor. People with green thumbs living in the cities have lesser options and have to deal with what they have.

Grow lights such as CFLs are not the only consideration. They may be a suitable alternative to sunlight depending on how you design them to operate, but there are other things to factor like soil quality, hydration, and even ventilation.

Such hindrances can now be overcome with the proper use of the technology available.

Additionally, having a little background in Economics is definitely an advantage in order to harvest what ambition you had planted in mind while investing in an indoor plantation.

I hope you are aware that some countries have the agriculture sector as the backbone of their economies.

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