If you’re starting to get into growing plants inside of your house, you may be wondering whether you can just grab a light bulb from the drawer, stick it over your plants, and be done.
For normal indoor plants (e.g. plants like those that come from Exotic Angel), a LED, Incandescent, or CFL bulb should be more than enough to grow a plant labeled as needing low or medium light. For high light plants or for growing vegetables indoors, you’re likely going to want something that puts out a bit more light.
Let’s talk about normal light bulbs and not so normal light bulbs that you can use to grow your plants under.
Do Normal Light Bulbs Help Plants?
Let’s talk about the different types of light bulbs you normally find in your house and which ones are best for plants.
Incandescent lights can help plants – especially low/medium light indoor plants – but they have issues that prevent them from being ideal for growing any high light houseplants or crops indoors.
The main problem with incandescent light is that they can become hot when they are in use. The lower watt lights produce less heat but don’t get bright enough to do anything, and the higher watt ones get too hot to use near the plants.
For plants with lower light requirements, however, it is possible to find a balance. A lot of these plants can grow indoors under normal lighting conditions with incandescent lights.
If you’re trying to use an incandescent bulb over your plant as a ‘grow light’, however, make sure to position the light far enough away from the plant so that the heat does not reach the plant.
LED and CFL bulbs solve a lot of the heat problems, and you can use a higher wattage bulb that will provide brighter light and put it closer to your plants. You can generally put LED bulbs within a couple inches of your plants to help them grow better.
Regular bulbs (CFL, LED, or Incandescent) are still not going to be a good choice for growing vegetables or fruiting plants, however, as they just don’t give off enough light for those types of plants.
The color spectrum of light is also an important consideration when choosing a light bulb to help your plant grow.
Most plants require red and blue-wavelength light to grow, and regular bulbs are in the yellow and red spectrum. (Plants can use green and yellow light, just not as efficiently as the red and blue spectrums.)
The best bulbs for your plants are the ones that emit cool white light (sometimes called daylight bulbs).
Grow Light Bulbs
If you’re not sure whether or not a regular light bulb will help plants grow, then you’ll want to try a grow light. Most of these lights use a full spectrum that’s more tailored to the needs of your plants, which means that they have a wide range of colors, including blue and red.
Older style grow bulbs will just use a combination of blue and red LEDs, but this has largely been phased out in favor of full spectrum bulbs.
You should be aware that they can be a bit more expensive than regular lights, depending on the type you get. A general range is around $5-15 per bulb depending on brand and power output.
For flowering and fruit-bearing plants, red-wavelength dominant bulbs are the best. For everything else, a blue-wavelength dominant light is best. The full spectrum bulbs try to balance this out and provide something that will work for all stages of plant growth.
If you pick up one of the more expensive LED grow light fixtures, you can hand tune these yourself, but for the cheaper grow light bulbs this is typically designed into the light.
These bulbs can be a bit better for growing plants than normal light bulbs are, since they are designed to produce light in the color range that your plants need. They can be good for growing most indoor plants, including some plants marked as “high light”.
They can also be okay for growing some smaller leaf crops like spinach, lettuce, or shorter herbs as long as you keep them very close to your plants’ leaves. Unfortunately, they’re not going to be good for growing much more than that if you’re looking at growing vegetables indoors.
The reason for this is their low wattage. They may advertise 100w equivalent, but the fact that they only put out 9w means they’re not going to be able to penetrate very deep, so only some of your plants’ leaves will get enough light for them to grow properly.
LED fixtures that are designed to grow demanding fruit and vegetable plants are typically at least several hundred watts in terms of real draw.
Still, they’re expensive, so picking up a cheaper grow bulb that will screw into your existing lamp is a good choice for most indoor plants and for getting started with some basic vegetables that stay short and don’t fruit or flower.
Proper Grow Lights
Now we’re getting into stuff you can use to grow almost anything in your house (including real trees). The answer to the initial question of whether these will grow plants is yes, almost regardless of what the plant is.
You may need a more powerful fixture for certain plants, but you can find one that will grow whatever you’re looking to grow.
Types of Grow Lights
The two main contenders for proper grow lights that are suitable for homes today are fluorescent lights and LED lights. There are other types of lights, but they get hot and require special equipment to set up.
LED lights are the cheapest to run in the long term and are the most flexible, being able to fine tune the amount and color of the light to suit the stage of life your plants are in at the moment.
The used to be the most expensive to buy up front, but prices on lower end models have come down a lot.
Super cheap LED fixtures will only run you around $20 and will put out enough light to grow a less demanding flowering/fruiting plant (or a few leaf crops in a small area). On the expensive side, you can easily pay more than $1,000 for a really good fixture.
Fluorescent tubes come in a variety of sizes including T12, T8, and T5. The smaller the number after the T, the more energy efficient it’s going to be. Also the more expensive it will be to buy. I’ll talk about T5 here because that’s one of the more modern types of fluorescent bulb, but this also applies to the other two.
An eight bulb, 4′ longT5 fixture will run you in the neighborhood of $100-150 to purchase.
When shopping for fluorescent tubes, you’re going to give up the flexibility of LED lights in terms of being able to dial in your colors specifically for the needs of your plants. Instead, you’ll find vegetation/growth bulbs and fruiting/flowering bulbs that have the different wavelengths designed into them.
Grow Light Sizes
Both LED and fluorescent fixtures are available in many sizes (how long and wide they are). If you don’t know what size light your plants need, the best idea is to find a chart for how the individual light your looking at spreads light.
LED lights will generally come with charts supplied by the manufacturer of the individual light that say how they will spread light across an area of a few feet squared. This will be measured in PAR, and you can google how much PAR your plant needs to compare it against.
Depending on the type and brightness of the light, you can keep it from 2″ up to 2′ above your plant effectively.
For fluorescent lights, an average 4′ eight bulb T5 fixture will provide adequate light over a 2’x4′ area in the shape of the fixture when kept 12″ above your plants.
Choosing the right T5 bulb for your plants will depend on their needs in the growth stage they’re in. For example, a reddish light will be best for flowering plants, while a blue-wave light will be ideal for plants that are primarily growing leaves.
The type of bulb you choose to grow your plant depends entirely on how much light the plant needs.
On a basic level, you can just go off of what the plant package itself says it needs (low/medium/high/full sun). Once you start to get more advanced, you may want to search the PAR requirements for your individual plant and compare that to what the light says it will output.
When in doubt, it’s probably best to go a little higher on the amount of light you think you need to be safe. Especially if you’re getting a LED grow light where you can dial up or down the amount of light your plant gets.