Can You Use Regular Light Bulbs As Grow Lights?

Who doesn’t love indoor plants? They bring the outdoors inside. But in the majority of houses, there isn’t enough natural light to grow more than a few basic house plants. People often assume you need expensive grow lights to make up for the lack of natural light, but you can actually use regular light bulbs to grow plants indoors. That said, you might not want to.

a grow light bulb

Before we get into that, you might be asking yourself how you would know if your plants aren’t getting enough regular light and whether they need artificial light to help them out. Believe it or not, your plants will tell you. Not literally, of course, but they will show you.

If your plants aren’t getting enough regular sunlight, they will grow tall with weak stems and the leaves will be lighter in color. New leaves will often be larger in size and the leaves on the inner part of the plant may start to turn yellow.

If your plants show these symptoms, you are going to want to get them some additional light. The most successful light bulbs contain both blue and red wavelengths of light. The blue is especially useful for foliage growth and the red is for flowering and fruiting.


Types of Light Bulbs Available

If you are thinking of growing plants from seeds, you’d be best off with hanging tube fixtures that you can place directly over your plants. There are special kits available that include the fixture and reflectors. If you just need light for your regular houseplants, any lamp or light fixture will do. You do want to make sure to choose the bulb carefully, as some will give you much better results than others. You also want to place the lamps where your plants will benefit the most from them.

The most popular types of light bulbs to use as grow lights are incandescent or fluorescent bulbs, but you can also use LED lights, halogen lights and traditional horticultural grow lights, like high-pressure sodium bulbs (HPS) and metal-halide bulbs (MH).


Incandescent Lights

Incandescent lights give off a substantial amount of heat so you don’t want to place them too close to the plants. They also generally give off more red light, so incandescent lights can be used to supplement fluorescent lighting, which gives off more blue light. This balances things out and is especially useful when you want your plants to bloom.


Fluorescent Lights

Fluorescent lights are the easiest choice because they are the most economical. They are sold in tubes or compact bulbs that go into a regular lamp socket and they stay cool enough that they can be placed close to your plants.

Generic fluorescent bulbs and tubes are higher in blue wavelength light, so when you are purchasing fluorescent lights to use as grow lights, look for “full-spectrum” bulbs or ones that have both a mix of “cool” and “warm” light. If you can’t find any of those, opt for “cool white” since this is closest to the spectrum of natural sunlight during midday.

The main problem with both incandescent and fluorescent bulbs is that they aren’t generally powerful enough to flower more than a couple of plants, unless you get a ton of them. That is not cost effective, however. If you have more than a couple of plants, you would be much better off with high-intensity discharge lights (HID) or LED lights.


LED Grow Lights

LED lights are more energy efficient and emit much lower levels of heat than other types of lighting. Keep in mind though, that because LED technology is so customizable, every bulb is different and you still need bulbs that produce the red and blue wavelengths required by your plants. There are horticultural LED grow lights available, which produce only the wavelengths used by plants, so you will want to look at purchasing these, as opposed to just general use lights. They are not cheap, however. That said, there are a few quality, inexpensive LED lights on the market.


Halogen Lights

Halogen lights also provide full spectrum light and are quite powerful, but they are similar to incandescent bulbs in that they emit a lot of heat and are not as energy efficient as fluorescent lights, HID lights or LED lights.


HID Plant Lights

Finally, we come to traditional horticultural grow lights. These are often referred to as HID lights and are further broken down into HPS and MH lights. HPS bulbs emit more of a red spectrum light, making them superior for flowering and fruiting, while MH bulbs emit more blue light, making them ideal for plant growth.

HID bulbs are very energy efficient. They may use a lot of power, emit a lot of heat and require additional components like a ballast, but they also give off a large amount of light that is powerful enough to flower any plant. For this reason, HID lights are still the light of choice for most commercial indoor growers, although LED lights are slowly taking that crown. Read more about HPS versus LED lights.


How to Set up the Lighting

For a small garden of a few plants in a room with very little natural light, a standing lamp with three bulbs and a movable or goose-neck feature works well. Use two fluorescent bulbs with the highest wattage allowable by the fixture and one incandescent bulb.

You want to aim the light towards the table with the plants. If your light fixture does have a movable arm, place the fluorescent bulbs closer to the plants than the incandescent bulb. This is to avoid heat damage.

To make more efficient use of the bulbs, place a reflective surface, such as a mirror or just some reflective foil, underneath the plants, so that the light can reflect back up towards the foliage. And finally, attach and set a timer to run the lights for 14 to 16 hours a day. You can do this manually, but it is easier with a timer and you can get a cheap one for just a few dollars.


February 9, 2017

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