Choosing Grow Lights

Choosing to grow indoor plants with artificial lighting 'grow lights' is crucial for certain types of plants and necessary to achieve desired indoor gardening results.

You’re probably aware of these points, however, they’re still worth mentioning. All plants have light requirement for the photosynthesis process to occur and growth but the amount for each species, genus or type can differ dramatically.

And, differ dramatically certain times of the year. Many indoor plants have a dormant or resting period - too much light would be tiring and unhealthy for them.

- Grow Light Uses

Picture of a flourescent bulb

Limited light: Artificial lighting is a suitable option for rooms that receive limited, no sunlight or even a room without windows.

Seedlings: One of the main uses for grow lights is to assist with propagation of plants from seedlings. Many seedlings need enough hours of light and warm enough temperatures which can be hard to provide in many homes. Near a south facing windowsill may be great for light, however, lack of correct temperature may cause issues or uneven growth.

Growing food: This is a great use for grow lights I find super beneficial for us that want our own fresh vegetables and herbs. It's no secret how vegetables and herbs have pesticides used to protect them that is not completely removed from our veg, even if washed and the lack of nutrition from good soil nowadays. There is more to growing correctly indoors than just light but it is a large part of the process.

Propagate: Because seed sowing can create numerous plants quickly some growers have started their own small business from seed sowing and then growing the seedlings in to plants to sell on. Having the growing space and of course lighting makes it possible. Many indoor gardeners also propagate to give plants as gifts.

- Plants That Benefit From Grow Lights

Many of your house plants are not going to require artificial light although most during the months of limited daylight would benefit. A sign they’re not getting enough light is spindly and limited growth, yellowing then dried up leaves and poor or no flowering.

These are a few examples that will benefit from supplementing light:

African Violets - Saintpaulia: The African violet most definitely benefits from supplementary lighting and is a favorite among many specialist growers. Fascinating varieties of flowers can bloom for the most part of the year with the correct conditions, including light.

Orchids: Orchids produce the most beautiful flowers in many colors with various petals and sepal shapes and sizes. However, growing them well is not easy. Minimum 10 hours of good light is required along with the correct temperature and high humidity.

Succulents: Most succulent plants are fine with the amount of light provided within a home and survive. Supplementing light during the daylight lacking months or in rooms without sufficient light will really help encourage a succulent and make them much happier. They will do more than just surviving.

Gloxinia: Gloxinia are beautiful plants but not easy to grow. Supplementing light and other factors can encourage growth and help with propagation (seeds and cuttings).

There are a number of other plants that benefit from artificial lighting including Begonias. With all plant care instructions including lighting - each must be considered individually.

- Light Intensity and Spectrum

Before discussing the type of grow lights suitable it makes sense to understand the basics of light intensity and spectrum. Different plants and method of growing (ie, supplementary lighting for foliage or flowering plants, starting seedlings or growing vegetables).

Light Spectrum

An easy way to visually think of light spectrum is how we see colors of the rainbow. The various light colors effect plants growth differently. This is not all visible to the naked eye.

Full spectrum means all colors (but means much more than just color named Electromagnetic spectrum) produced from natural light and a term used for grow lights. Sunlight is the ultimate full spectrum.

As we know every species needs a certain amount of light to thrive and full spectrum is supposedly mimicking sunlight ranges much better and on wider scale than just bright white light. Interesting article explaining full spectrum is a marketing term used for selling grow lights.

A full spectrum grow light is sold and suitable for aquarium plants, certain flowering plants and growing plants with artificial lighting as the primary or only source of light. And plants that need more than just a few hours of bright light supplemented.

Basics of Colors:

Blue is used to encourage bushy growth in plants, the vegetation and the germination of seeds 'stage of growth'. Red colored light is for encouraging budding, flowering and fruiting. That is a simple way to view light spectrum without over complicating how terms are used.

To be more accurate and following an easy way of choosing the right color spectrum rather than getting too technical is following the color temperature spectrum, named kelvin scale and CRI (color rendering index). I write easy way because specialist growers will look at many factors such as nanometers, PAR (photosynthetically active radiation ) and CRI (color rendering index) and I am writing for the beginner and average home grower trying to keep technical terms to a minimum.

Kelvin scale bulbs: 6500K are the most popular for growing vegetables and seedlings and young plants needing a lot of light and growth. 3000K to promote budding and flowering. 10000K used for aquariums. The higher the kelvin the cooler and the lower - the warmer. Using African violets as an example. They will need both blue and red, blue for the leaves and plant production and red for flowering. Full spectrum bulbs are likely to be the best option especially if natural light is very limited.

For full spectrum it is worth mentioning and considering the CRI (color rendering index) of the lighting. This indicates and measures the rendering of color within its spectrum.

Light Intensity

While light spectrum is obviously an important factor, so is light intensity – too much or too little will cause plant problems and growth issues.

Watts, lumens, LUX and foot candles, confusing, I know. The basics are as follows, watts are not the light output but rather the rate of energy used (higher the watts, more electricity used) and lumens are the light output used as a measurement (the brightness). Footcandles are also used as a measurement and began many years ago when candles were the light source. LUX is also a metric measurement of light.

This could all go over technical, so I will stick to what measurement you can use for buying your grow lights, which is wattage and lumens. Higher the wattage the higher the energy input into the bulb and usage, and the higher the lumens the brighter the light and output. You will now find lighting has advanced and bulbs are produced that keeps the watts low (reducing energy costs) and lumens high (brighter light).

Now you have the important basics, watts is the energy used, kelvins are the type of light color provided and lumens is the amount of light output. Looking at all three of these when buying will help you decide the efficiency costs, the correct amount of light and the right mode of lighting.

- Types of Grow Lights

There's a large amount of information about growing with lights, the best technology to use and testing done. These are the basics that will point the average indoor grower in the right direction.


Fluorescent lighting is still the most popular used for supplementing light during the winter months, encouraging flowering and starting plants off with seeds well. Most are more cost efficient than other high intensity lighting or incandescent bulbs and many set ups can be bought with the frame, fixtures, a small lamp or just a bulb. Fluorescent light produces less heat that can be harmful to plants than incandescent and high intensity discharge (HID) lights, although cooling can be provided with HID's.

Bulb types include CFL (small compact florescent bulbs), T5 and T8 (different diameter sizes and T means tubular). T5 florescent tubes are the most popular used and purposely made for use as grow lights, although some people grow plants well with the T8s that are cheaper. This forum post gives you an idea of the differences and some great points about choosing T5s, T8s or HID (high intensity discharge lights). For the average indoor grower and beginner T5s are the best route to take.

LED Grow Lights

Light emitting diode lights over the past few years have become more popular. The claims for using LED's over other types is they cost less in terms of consuming a smaller amount of electricity compared with florescent and HID lighting. They also do not produce too much heat which can damage seedlings or effect plant growth.

LED's are cheaper in terms of electricity usage and bulbs last much longer. Buying an LED unit can be more expensive though, but most buyers state the fact that long term they reduce costs. Low energy usage and high in efficiency.

In comparison tests I have reviewed this article is interesting and states florescent lighting produces better results growing seedlings and herbs. This report also has a reply from the LED supplier stating why the LEDs did not perform as well, interesting test. . The second experiment also shows florescent producing better growth results.

Since that experiment LED's have advanced more and are recommended as the best option by many growers, especially the marijuana growers. However, I’m not in a position to say buy one or the other – it's pretty much up to your own research and setting up the correct growing conditions. Results have been proven over a long period of time and many times from florescent lights, though.

Various types of units are sold and different sizes. Even single bulbs are sold the same as florescent CFL's. An issue with LED grow lights compared to florescent is cost per coverage. Long florescent tubes will cost less to cover more space.

Appearance of plants is important for most plant growers within a home and LED's don’t look very attractive, whereas many florescent units and how the lighting appears look appealing indoors.

High Intensity Discharge (HID)

The two main types of HID are Metal Halide (MH) and High Pressure Sodium (HPS) used for indoor gardening. Which type a grower would use is based on what 's being grown, the yields they want and color spectrum.

HID lamps provide the highest light intensity. For the average home grower the expense of setting up, and the electricity bills may be above what you would like to spend if you’re planning to start some seedlings, learning to grow and flower AV's or supplementing winter lighting.

I wont go into a lot of detail regarding these light but if becoming a serious grower is part of your plan then I would suggest HID's are the way to go.


For most home growers supplementing lighting, growing herbs or starting from seeds; florescent lighting with T5 tubes or CFL's for lamps are suitable. Kits are sold with the frame, trays, fixtures and bulbs which makes preparation and choosing easier. You also have the option of creating your own light system.

For the serious grower that wants larger yields of plants they will be looking into providing lighting from HID lamps.

I’m not quite sold on the LED's for growing plants at home, although the marijuana growers are having great success. For the marijuana growers the main purpose is to grow for their crops and nothing to do with appearance within a home.

Understanding technical information about light spectrum, lumens, CRI (color rendering index)and PAR (photosynthetically active radiation ) measurements is wise when becoming more serious about growing. This will enable you to choose the right grow lights which are also efficient in costs when comparing all aspects, i.e., wattage, light output, set up and replacements.

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