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For people who enjoy indoor gardening, having enough light for all your houseplants is probably the biggest challenge.
Even those with an abundance of windows and natural light often have to resort to lamps or other types of artificial light. It’s just part of the houseplant game.
But there is a lot more to managing artificial light for your plants than just flipping on the overhead room light.
Did you know there are different kinds of light, and that some plants do better with it than others?
Different Types of Artificial Light for Optimal Plant Growth
This is the surprise for most people. The idea that there are different types of light isn’t obvious, but it can be a critical thing to understand so you can make the most of your plant lights. We’re talking about light itself here, not fixtures or bulbs.
To the untrained eye, artificial light looks white. It’s really a combination of different color wavelengths, and you can choose your light to focus on one color over another to get different results with your plants.
Basically, you need to know about blue and red wavelengths in light. Without getting into an in-depth lecture about the physical properties of light, you can remember a couple of basic facts. Red light will encourage plants to flower or produce fruit, and blue light boosts leaves and foliage growth.
Most typical lights are a balanced blend of the two, and known as full-spectrum light. When in doubt, or if you are trying to accommodate many different plants with one light, stick with this.
When we talk about the color spectrum, this isn’t the same as getting an actual blue or red tinted bulb, like Christmas lights or something. The light is still primarily white, just with a light shift one way or the other in the wavelength.
In home decor terms, blue-dominant and red-dominant light is called cool and warm, so you can look for that sort of labeling when trying to get the right bulbs. It is not actually about temperature in anyway; the terms refer to the “feel” of the light and its color saturation.
Different Types of Light Bulbs
The previous section was more of a look at the properties of light itself. What about the different kinds of actual light fixtures?
These days, you have quite a selection of bulb formats and they’re definitely not all the same.
These are the older bulbs we all grew up with, that have a fine wire filament in the center that heats up to make light. Cheap and short-lived, these are no longer the only bulbs you have to choose from.
Don’t be afraid to check out the more modern bulb types when shopping for your plant lights. These types of bulbs often come in cool or warm tones but will generate a lot of heat over your plants.
LED lights are also quite expensive, especially if you are used to buying a pack of bulbs for a dollar or two.
When you’re looking at fluorescent lights for plants, you have a few additional options. There are the usual long, straight bulbs that you use in a particular type of fixture (think office lights), or the newer spiral type that usually work fine in any lamp.
You’ll likely have more choices with fluorescent bulbs in terms of color spectrum due to the way they work.
Halogen bulbs aren’t as common, though they do have their place. They’re bright and will last a long time, but the light they produce isn’t the best for indoor houseplants. It leans to the red end of the spectrum, which will help with flowering but not overall growth.
You should consider halogens as supplemental light with other bulbs or daily exposure to natural sunlight.
Don’t be fooled by creative labeling, and spend too much money on special grow-lights. That doesn’t mean that they don’t have a place or are worthless, it’s just that they aren’t necessarily special.
A plain fluorescent bulb on the blue-side of the spectrum is going to do the same thing as a “grow-light” on the blue-side of the spectrum.
Which type of light bulb is the best? Each one has its issues but most people prefer fluorescent lights for their houseplants. They are relatively inexpensive, long lasting, allow you to adjust for spectrum values and don’t heat up.
The formats (long tubes vs compact bulbs) also gives you more flexibility in how you use your light fixtures when you have a large number of plants.
How to Use Artificial Lights
You’ve decided on color and bulb, so now what? What is the best way to implement some artificial light for your houseplants?
If you are talking about indoor plants in a room that stays lit all day long, like a living room or a business office, you may not need any extra lights at all. The room light alone may be enough for low-light plants.
For plants that do need a little more than ambient light, you’ll want to have your lamps set up closer to the plants to get that extra intensity. When using a bulb type that doesn’t generate any heat (fluorescent or LED), you can set up your lights quite close to the plants.
Plants that prefer really bright light, like African violets, are happy with lights set only 10 inches away.
Don’t forget that using artificial light isn’t an all-or-nothing technique. You can take advantage of natural sunlight through the spring or summer months, and then just supplement with additional light during the winter when the sun isn’t helping out enough.
Feel free to mix and match window light and artificial light in whatever way works best for your space.
How Much Light Is Optimal?
A timer (link to Amazon) is an excellent, low-cost investment and can keep your plants well lit without you having to worry about anything. This is especially handy when you are trying to maximize your lighting hours and want the lights to come on before you’re up in the morning.
Even if you are not worried about being there to turn the lights on or off, you do need to plan for timing. Relying on the natural cycles of day length aren’t going to work with artificial light.
Not all plants require the same amounts of light, so a little research can help with this.
Geraniums, begonias, chrysanthemums and coleus plants will do just nicely with 8 to 10 hours of light. On the other hand, vegetable seedlings can require 12 or more hours.
To complicate things even more, some plants need to have the light adjusted through the year to simulate the dormant period of winter. Without it, many flowering plants won’t enter their bloom cycle. For them, plan on reducing the light for a few months before bringing it back up.
And if you are thinking about raising a batch of super-plants by leaving the lights on 24 hrs a day, think again. Yes, plants need light to grow and thrive, but they also need that period of darkness to rest and focus on respiration instead of photosynthesis (read about that in my post about the necessity of darkness for plants).
Leaving the lights on more than they can handle is doing more harm than good.
Plants that Thrive in Artificial Light
In general, plants that do well in low-light situations are the ones that will thrive the most under artificial lights. Some suggestions are:
- Peace lily
- Cast iron plant
- Peacock plant
- Snake plant
- Sword fern
- Spider plant
You many notice that these low-light plants are also pretty well-known as indoor air cleaners, so there is even more added benefit to your space to have them.
Regardless of which plant you choose, you’ll want to take a little extra care with watering. Without the warmth of sunlight, indoor plants under artificial lights often need less water than you would expect. Watch out that you don’t over-do it.
Pros and Cons of Using Artificial Light
The main positive for using artificial light with your houseplants is the obvious fact that it allows you to grow plants that you wouldn’t be able to have indoors due to a lack of light.
You can also take a bit more control over your lighting options to help with the growth of your plants. Instead of relying on plain old sunlight, you can tweak your spectrums and give your plants an advantage they wouldn’t otherwise have.
In particular, being able to add red wavelengths of light can make it possible to have flowering plants that just won’t bloom in regular indoor sunlight for you.
A small side benefit to using the older incandescent bulbs can be the heat they put off. For plants that like warmer temperatures than your home usually offers, a few lights can raise the temperature as well as the light level.
Depending on how reliant you are on lamps, one drawback can be the cost. Modern LED or CFL bulbs don’t use all that much power so this isn’t as much of a problem as it once was.
Still, a whole lot of electric lights can have an impact on your power bill, especially if you are still using the “old-fashioned” incandescent bulbs. Bulbs like LED will have a significant up-front cost too, sometimes more than $10 per bulb.
Being dependent on electric light can also be a bit of a risk if you have a power failure. Granted, your plants will be fine for a few hours without their lamps but if it were to go on for too long, you can end up with stunted or dying plants.
There is also a bit of a risk having too many lamps set up around when it comes to watering time. For the serious indoor gardener, it would be a smart move to install some GFCI outlets in your plant area. A simple mishap with a watering can around a rack of electric lights can be a serious shock risk.
So if you are struggling to manage your collection of indoor plants because you just don’t have enough windows, you can use these tips to add some artificial light to your growing space.