Artificial Grow Lights vs The Sunlight for Plants

close up of leaves with ray of sunlight

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Sunlight has the ideal wavelength balance for plant growth and blooming, but you may also utilize artificial sunshine to assist your plants. In fact, with adequate artificial light, low-light foliage plants (such as pothos and peace lily) may thrive pretty well in windowless spaces. In fact, if you’re trying to grow houseplants indoors, you’ll notice that some rooms in your home lack natural light. And while sunlight can provide adequate light, it may also harm indoor plants when it’s too strong. 

It’s essential to understand the characteristics of the light spectrum and how much heat your indoor growing setup is providing in order to garden indoors effectively. The different wavelengths of light found through both sunlight and artificial lights each produce a unique hue. The color of the light, seen when passed through a prism, forms a rainbow.

If you have the appropriate setup, you can effectively grow plants indoors using artificial light. Plants are pretty fond of red and blue colors in particular, as both are critical to plant growth. However, many artificial light sources supply green and yellow light, which offer insufficient energy for plants. Some lights emit only red or blue light, with no variable combinations. 

Grow Lights vs. Direct Sunlight

Sunlight is abundant and free, providing all that plants require. The blue spectrum encourages healthy leaf growth, while the red spectrum encourages flowering and fruiting. Plants that require a lot of the sun should live by a south-facing window unobstructed by trees, roof overhangs, or other barriers. As beneficial as sunlight is, you might give your indoor plants too much of a good thing. Plants that don’t need much light thrive in windows that face west or east. A north-facing window is best for low-light plants.

Artificial lights cannot duplicate the exact hues of light (wavelengths) beneficial for plants; hence sunshine is better for plant growth. In fact, the energy delivered by most grow lights in up to 13 hours is equivalent to the power provided by the sun in only 6 hours! On the other hand, artificial lights can be an excellent way to supplement sunlight, especially in the winter or when there just isn’t enough.

Types of Artificial Lights

Fluorescent Lights

Fluorescent lights are by far the most cost-effective and straightforward option for houseplants. They come in tubes or compact fluorescent bulbs (CFLs) that screw into standard lamp sockets and emit a low enough temperature to put near plant leaves. Because generic fluorescent tubes and compact bulbs have a more significant concentration of blue wavelengths, look for full-spectrum bulbs or a mix of “cool” and “warm” bulbs. When in doubt, opt for white light, which contains the entire spectrum of wavelengths. Place fluorescents approximately a foot away from plant foliage for the best impact.

Incandescent Lights

Because incandescent lights produce a lot of heat, they should hang further away from plant leaves. Incandescent bulbs also emit more red wavelengths, so growers can use them to supplement fluorescent light and balance the spectrum, especially when stimulating plant blooming. If you want to mix the two, attempt a wattage ratio of one-third incandescent to two-thirds fluorescent. 

LED grow lights

LED Lights

LED lights are a low-heat, energy-efficient source of artificial light, as compared to regular light bulbs. Because LED technology is so adaptable, each bulb is unique. Make sure your bulbs emit the blues and reds that plants require. Horticultural LED grow-lights provide only the wavelengths most used by plants; therefore, you should opt for these bulbs rather than buying general-purpose bulbs.

Halogen Lights

Halogen lights can also offer full-spectrum light, but they emit a lot of heat and are less energy-efficient than fluorescents. Be wary of light bulbs labeled simply as “plant” bulbs. They only improve the appearance of your plants by making them look more green, but they’re just colored incandescent bulbs. Some examples of popular halogen bulbs are the High-Intensity Discharge (HID) light, Metal Halide (MH) bulbs, and High-Pressure Sodium bulbs (HPS).

Also read; LED Grow Lights Vs. HPS: The Ultimate Comparison Guide for Indoor Growing

Horticultural Grow Lights

Horticultural grow lights often come in fluorescent fixture tubes. They contain the entire spectrum of wavelengths required for plants like the African Violet. Some gardeners find them handy for beginning seeds or propagating hybrids, but others think that simple full-spectrum fluorescents work just as well. 

How To Decide: Grow Light or Sunlight?

You may not have abundant natural light in every room in your home. And even if you have windows, solar intensity is often filtered away before reaching your plants. It’s not as strong as direct sunlight, or a grow light. If the sun isn’t in sight of the window or anything blocks it, the light that does come through can be even less intense. Windows with less light mean the plants that demand a lot of light on a windowsill will not do that well. However, since (with grow lights) you can modify how near they are to the plant and add or remove the lights to control the strength of light, you can ensure that your plants get the light they need! 

Plants that might not thrive near a window tend to like lower temperatures, as the glass can magnify the heat from the sun. During frigid winters, windows can also injure your plants with the cold. The plants next to the window may not remain warm enough if too cold or even frozen.

Utilizing grow lights allows you to put your plants wherever you choose and protect them from harsh temperatures. In fact, grow lights can be better than sunshine sometimes, even if you have open-air space.

Certain plants prefer partial or shaded light, as they would wither under the full sun. Many plants will not thrive well outside if you have no shaded outdoor space. Conversely, certain plants prefer direct and complete light. Your plants will not get enough light if you only have shaded outside areas. Furthermore, depending on the season and place, sunshine may be challenging to locate at times.

Artificial lights ensure that your plants have regular access to enough light throughout the year. You could also mix the two sources, using sunlight during the day and artificial light at night. Try to leave the plant under artificial light for a few hours if you believe your plan is not getting sufficient sunshine. Regardless, your specific situation will determine what works best.

The Best Small LED Grow Light

Pros & Cons

Garden Customization

Pro: Artificial lights allow for nearly endless customization options in your garden. Depending on the time of year, a houseplant may need a different light to optimize its growing phase. You can fine-tune which end of the light spectrum to display with a grow light, how far away the lights are from the plant, and precisely how much energy your plant absorbs. 

Con: Sunlight does not allow for much customization if any at all. You may have to get creative about where you put your plants to maximize sun exposure, but otherwise, all the variables are already predetermined. Sunlight is especially limited during winter months or in heavily shaded areas. Of course, plenty of plants survive in natural conditions, but you may just have to be a bit more patient.

Cost-Effectiveness

Pro: Sunlight’s most significant selling point might be that it’s not for sale. Everyone can take as much as they want! If up-start costs keep you from indoor gardening, just know that your light source is ready to go. It might not be the most sophisticated option, but the sun has been giving off light for right around 4 billion years and doesn’t seem to be stopping anytime soon.

Con: Artificial lights don’t have to be expensive but cost at least a little money no matter what. And honestly, with all the different gadgets and customization options available, the price can stack up quickly. If you’re concerned about light quality, you could easily spend at least $100 for an entry-level light.

Growing Location

Pro: With an artificial grow light, your garden can be wherever you want it. Even in small spaces with no windows, a grow light will maximize your location options. Different plants might need a different spot across the house, so multiple lights should allow for the perfect set-up.

Con: The sun follows the same pattern every day. Or, I guess we do (see: heliocentrism). What I mean is that you have to move your plants to reach the sun, rather than the sun to meet your plants, limiting the options for your garden’s location. If you live in a shaded area or want to start growing in the winter, you might have to significantly reduce the list of plants you were hoping to raise. Of course, it’s possible, just restricted. 

Heat Regulation

Pro: Grow lights tend to have low heat outputs, especially if you’re using an LED. Even if the light gave off significant heat, you could adjust the distance between the grow bulbs and plants accordingly. However, some older artificial lights are known to get very hot (i.e., HID), so keep this in mind when using them in your garden.

Con: Sunlight is powerful and hard to control. Especially when you consider glass windows magnifying its rays, the sun can easily scorch your plants or simply dry them out too quickly. Some plants can handle the heat (like many desert plants), but generally, filtering the sunlight with some sheer curtains or a few feet of distance is ideal.

Light Intensity

Pro: If you’re trying to blast your plants with as much photon food as possible, the intensity of light produced by the sun is hard to beat. The sun gives off the entire light spectrum that your plant needs for optimal growth, all at once—no need to wonder which wavelength is headed your way or whether or not your plants like it.

Con: It’s not that artificial grow lights can’t produce intense light. They just need to work harder at it than the sun does. HIDs, for example, give off significant heat and energy but lack the entire spectrum. On the other hand, LEDs can cover all the necessary wavelengths but don’t always match the intensity needed for abundant harvests.

Seasonality

Pro: No matter the time of year, a grow light can work to its fullest potential. Whether you need a couple of more hours of daylight during the summer to maximize your yields or need to supplement the dark winter months just to keep your garden alive, artificial lights can get the job done. Rain or shine, just plug it in.

Con: Plants need darkness, and the sun seems to know this. However, sometimes our plants don’t need quite as much darkness as the sun thinks. Young plants are susceptible to lighting conditions, so a grow light might be necessary to keep things moving forward depending on when you add to your garden.

Energy Consumption

Pro: If you’re looking for an environmentally friendly option, the sun is the most natural option. It’s free, it’s good for us, and it’ll be around for quite a while. It even produces energy rather than consuming ours. Plants take carbon dioxide from the air, so why would we cancel that out with unsustainable lighting systems?

Con: Artificial grow lights consume energy, and some of them consume a lot of it. Many of them contain pieces that are not easily recyclable, too. LEDs have made many strides toward being environmentally friendly and are by far the best-manufactured option. For the best of both worlds, look into some solar-powered grow lights.

Do Plants Grow Better Under Sunlight or Artificial Light?

Sunlight is a crucial component of plant growth. Your plants will not flourish if they do not receive enough light, which plants typically receive from the sun. However, we have discovered techniques to grow plants using artificial lights as well. While some artificial lights do an excellent job of sustaining plant life, can they genuinely substitute for the sun?

Light occurs in a variety of colors, and plants require red and blue light in particular. Red light stimulates the growth of flowers and fruit, while blue light stimulates the growth of leaves. The complete spectrum comes from sunlight. However, most light bulbs only emit yellow or green light, while some emit red or blue light, but not simultaneously.

However, many grow lights satisfy and cover the entire spectrum. As a result, broad-spectrum grow lights are nearly as effective as natural sunlight! Even still, sunshine is far more potent than grow-lights. A plant receives roughly the same amount of light energy from 13 hours of exposure to a grow lamp as it does from only 6 hours of exposure to the sun.

Furthermore, sunlight is free! You have to purchase grow lights and pay for the energy required to run them for hours at a time. So, if you’re going to garden outside or on a windowsill, sunshine is usually the best light option. Grow lights, on the other hand, function better for specific plants and growth scenarios. If you don’t have an outdoor location to grow plants in, grow lights are almost always preferable to natural light.

Effects of Artificial Lights on Plant Growth

Purdue University researchers discovered that LED lights, in certain combinations, can be as effective as sunshine for seed growth. As this research progresses, it may have ramifications for agriculture around the world.

Unlike the sun, the intensity of an LED bulb remains constant throughout the day and middle of the day, midnight, mid-summer, and mid-winter. LEDs provide the same continuous and direct light to plants, no matter what. LEDs can also be programmed to emit specific hues, such as the red and blue light that plants require to thrive. Finally, like all other components of indoor farming, LEDs provide farmers with something they can’t get from the sun: control. LEDs can create 20-hour sunny days by brightening, dimming, or altering the hue of the light depending on the crop.

Because of this increased control, you can dial in plants toward abundance. Gardeners can avoid scorched leaves and maximize harvests. 

plant growing under purple light

Can Plants Use Artificial Lights for Photosynthesis?

Not all light wavelengths are suitable for photosynthesis. Plants produce Photosynthetically Active Radiation (PAR) in the 400-700 nanometer range when they photosynthesize electromagnetic radiation. And Photosynthetic Photon Flux Density (PPFD) is the amount of light that actually reaches your plants within the PAR region or the number of photosynthetically active photons that fall on a given surface each second, per square foot. Sorry for the science jargon! 

On the other hand, plants are entirely unconcerned about how brilliant your light fixture appears to you— unfortunately, most of the ‘full spectrum of light’ options that manufacturers design only have aesthetics in mind. Plant photobiology has come a long way in our understanding. We know far too much about plants to build our grow lights using the human eye as a lighting measurement.

While PAR is the most crucial light for photosynthesis, plants nevertheless respond to other wavelengths. For example, UV light protects plants in the same way it gives humans a tan. Not all PAR light contributes to photosynthesis; however, different wavelengths of light, including green, do.

Photoreceptors and pigments in plant leaves absorb light for photosynthesis. The most well-known coloring is chlorophyll-a, but several other colors are involved in photosynthesis.

Red light has grown popular among LED grow lights due to its effective light absorption. Regardless, you’ll want to pick a grow light that gives you the desired outcomes, usually bigger yields, and better plant quality.

Is a Grow Light Considered Indirect Sunlight?

When it comes to satisfying the demands of your plants, you might’ve heard the term “indirect, bright light.” Indirect light is when the sun’s rays do not travel directly from the sun to the plant. It will instead bounce off anything before that. Sunlight can be direct or indirect. It all depends on where the plant sits and how the sun shines on it.

Plants under indirect light cast hazy and indistinct shadows. This light is comparable to around 800-2,000 ‘foot candles,’ an obsolete illumination unit equal to that provided by a source of one ‘candela’ from a foot away.

Gardners can use a grow light to simulate either indirect or direct sunlight, though it depends entirely on the power of the grow light. Most grow lights used by gardeners are indirect or low light, with a bent toward the latter.

It might be difficult to tell the difference between direct and indirect light. When your plant wants indirect light, you can use either sunlight or grow lights, as both are indirect if your plant sits strategically. When using a grow light, you may adjust the intensity and temperature to meet your plant’s needs. Consider placing your plants a few feet away from a sunny window or with some sheer curtains in between when using sunlight.

Which Color LED Light is Best for Plants?

As you’ve heard before, plants are particular about the light they absorb. Indoor grow lights provide them with the correct red and blue wavelengths for growth. But why red and blue?

Summertime is when the red light is most abundant. Using a unique light receptor, plants release a hormone that prevents chlorophyll breakdown. This allows the plant to benefit from ample sunlight in the spring and summer. Red light produces enormous, healthy plants because chlorophyll converts light into cellulose. Red light is also required for flowering and fruiting. Remember that too much red light can cause significant problems, such as lanky and spindly plants.

Spring and summer have more red light, whereas fall and winter have more blue light. When the plant’s blue light receptor detects more blue light, it releases a hormone that slows stem and leaf growth. As a result, many people avoid using blue grow lights, even though having at least some blue light is essential. Plants exposed to more blue light tend to be short and bushy, with a more complicated stem structure. Too much blue light stunts plants.

Most indoor growers propose a 5:1 red-to-blue light ratio for the best of both worlds. The high red light keeps plants developing, while the low blue light encourages stem growth.

However, if you only use standard fluorescent bulbs, you will only get light from the blue side of the spectrum, whereas incandescent lights will give you a glow from the red side, which can harm the plant’s growth.

To sum it up, blue wavelength light promotes the growth of leaves, whereas red wavelength light promotes blooming, fruiting, and vegetative growth. Plants use green wavelengths minimally and reflect them, which is why leaves appear green.

Can Plants Grow in Total Darkness?

Plants are unable to thrive in complete darkness. Except for a handful that live on other organisms, all plants obtain their energy through a process called photosynthesis. Most plants are autotrophs, meaning they feed themselves and need sunlight to exist.

However, plants do require at least some hours of darkness to grow. While photosynthesis requires light, studies reveal that dark cycles assist plants in preparing for the next day. In addition, some plants need periods of darkness specifically to begin flowering.

Most popular houseplants can thrive with 12 to 14 hours of artificial light if they don’t get enough sunlight. Plants that require roughly six hours of daily sunshine benefit from higher light intensity and should be placed no more than one foot away from the lights. Low-light plants thrive in the shadows or with fewer than four hours of direct sunlight, so put them 2 to 3 feet away from the light source.

Although the intensity requirements of many plants vary, the quantity of lighting time required from artificial methods is the same. Provide your plants with an additional two to six hours of artificial light in the evening if they receive some daytime sun but not enough to meet their needs, such as from a nearby window.

Is Constant (24-Hour) Light Bad for Plants?

When it comes to effectively keeping an indoor garden, lighting can be the most challenging factor, especially if you don’t have a window that lets in a lot of light. When grown under plant lights, plants require more time in the light, but how long depends on the individual plant’s needs, the light intensity, and the sort of lighting you supply.

In general, grow lights should not be left on 24 hours a day, seven days a week. To develop effectively, plants require a light-dark cycle. It’s thought that during periods of darkness, they actually “relax” and that they use this time to transport nutrients into their extremities while taking a vacation from developing.

Remember that the amount of light your plants receive is just as significant as the type of light they receive. Plants outdoors are subject to a natural cycle of light and darkness, with the amount of light varying with the seasons. Constantly exposing your indoor plant to light may be detrimental to its health. Plants require 16 to 18 hours of light each day; however, low-light plants may only need 12 to 14 hours. When in doubt, set the light timer to match what the sun is doing in your area.

Daily Light Requirements

The light duration needed varies depending on the type of plant in question. Generally, plants require between 12 and 18 hours of sunlight every day, so knowing this will help you determine how much artificial light they need.

Indoor gardeners often use artificial light for starting seeds. The containers with the seeds should be located less than six inches from the light source. The light source will need to be adjusted upwards as the seeds germinate and expand to a maximum of six centimeters.

Put mature plants within ten feet of a sunny window. The plant will “reach” toward the window after some time; rotating the plant keeps the plant growing evenly.

Plants using just artificial light should be placed six to twelve inches from the lamp with the tips of their leaves. The plant can reach toward the light bulb as if it is sunlight. Consider spinning the plant periodically or place it beneath the light source for even growth. Gardeners should give plants artificial light every day for 16 to 18 hours.

Temperature Regulation Concerns

The sun is a powerful and challenging-to-regulate source of light. The sun can easily scorch your plants or simply dry them off too soon, especially with glass windows intensifying its beams. Some plants can withstand the heat (for example, many desert plants), but in general, blocking the sunlight with sheer curtains or a few feet of distance is preferable.

Take note of the temperature and light levels on your window sills. Temperatures between 60 and 75 degrees Fahrenheit are ideal for most houseplants. Direct sunshine can be amplified by window glass, resulting in high heat that can harm some plants. A draft from the window might injure fragile plants in the winter. If the windowsill is too hot or chilly, place it on a stand or table a few inches away from the window.

Grow lights offer modest heat outputs, especially when using LEDs. Even when a light emits a lot of heat, the distance between the grow bulbs and the plants can be adjusted. However, some older artificial lamps (e.g., HID) have been known to get excessively hot, so keep this in mind while using them in your garden.

How To Grow Houseplants in Artificial Light

Hanging-tube fixtures placed directly over your plants are often recommended for advanced indoor lighting, growing, and seed starting. You can purchase specific grow light kits that include fixtures and reflectors. Still, you can use any lamp or light fixture for typical houseplants as long as you carefully select the bulbs and arrange the lights where your plants would benefit the most.

For photosynthesis, plants simply need PAR light. As a result, if your grow light supports the PAR spectrum, you’ll get the most for your money in terms of lowering power expenses while increasing plant health.

Artificial lighting allows for practically limitless horticultural modification options. A houseplant may require varied lighting to enhance its growing phase depending on the time of year. You may fine-tune which end of the light spectrum to display, how far away the lights are from the plant, and how much energy your plant receives when using a grow light.

purple bulb grow lights above plants in the window

How To Combine Sunlight and Grow Light

The easiest method to provide your plants with the light they require, especially if you don’t have much full spectrum, is to take advantage of what you have and use artificial light as supplemental light. When utilizing artificial light, just make sure the light is directed directly at the plant.

Although artificial lighting allows you to set your plants wherever you like, it is better to place them in a location that also receives some natural light. Your plants will thank you for supplying them with as much natural light as possible, even if it isn’t much. 

Beginners and professionals alike are increasingly turning to greenhouses for their gardening needs. There are numerous reasons why this planting environment is appropriate and beneficial. When employing a greenhouse, home gardeners can benefit from the best of both indoor and outdoor cultivation settings.

Growers can take advantage of the sun’s natural (and free) light in greenhouses. Furthermore, most plants can survive in a sheltered habitat that is less susceptible to natural factors (temperature, humidity, pests, etc.).

Humidity can also be easily controlled and supplemented in a greenhouse. Year-round, additional artificial lighting can ensure sufficient light conditions and even growth. Black-out tarps allow you to create dark circumstances whenever you want. 

Whether you use a greenhouse, grow outdoors and receive the benefits of natural sunshine, or grow indoors and enjoy the peace of mind of a climate-controlled environment, there’s a setup that will work for you!

How To Choose the Best Grow Lights for Indoor Plants

When choosing a grow light for your indoor plants, look for full-spectrum bulbs with a mix of cool and warm wavelengths.

Depending on your garden’s requirements, the most common wattages are 200, 400, 600, and 1000 watts. Home growers mainly utilize the lowest wattages, whereas commercial gardeners in food production use lights of 1000 watts and up. The electric output and power supply constraints should be consistent with the lights used.

Several wattages and styles provide standard indoor cultivation lighting options, which are typically combined with reflective light hoods to increase efficiency. These hoods are meant to return the light to the canopy of the plant. However, how effective they are might differ significantly depending on the style. Some hoods are vertical and domed, while others are flatter and horizontal.

These cutting-edge grow lights get the closest to imitating the dynamic properties of sunshine. Because spectrum control is necessary for scientific or commercial applications requiring precision, the options are unlimited.

Also read: Best Grow Lights For Indoor Plants & Small Spaces

Conclusion

Determining the best way to maximize your plants’ growth or picking the best LED grow light for your situation requires more than a simple answer. In fact, every situation is at least a little different. My advice for your best bet is to maximize your gardens’ exposure to natural sunlight and supplement any additional needs with an artificial grow light. You don’t have to take any chances on whether or not the sun is “right” for your plants, and simply monitoring heat exposure is about all the upkeep necessary.

As far as grow lights go, LEDs are quickly becoming the industry standard, if they’re not so already. Take advantage of the customization options, opting for a light with full, white wavelengths that can be dialed to the spectrum’s blue and red ends. A built-in timer is an added bonus. You won’t need much else fancy equipment, and there are plenty of reasonably-priced options. 

No matter what you choose or the environment you find yourself subject to, perfecting your setup will take time! And I think the experimentation is fun. Visit some local plant stores and ask how they keep so many plants thriving all year round. Observe temperatures, growing patterns, times of the year, and the effects of different stimuli on your plants. You’ll be a professional in no time.

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Brent Hellendoorn

Brent is excited about all things minimal, and thus environmentally sustainable. From kitchen-scrap composting to indoor herb gardens and air-purifying houseplants, he enjoys continual learning and innovation. In simple, eco-conscious living, there is always room to… grow!

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