5 Types of Light for Plants

There are different ways you can achieve the best kind of lighting for your plants’ best growth, and not just for that #goodlightingvibes aesthetic. But first, why does it matter that your plant friend gets light?

Light is necessary for plant growth, allowing them to photosynthesize and create energy to develop more. It’s also important to place indoor plants in the correct window cardinal direction to ensure they get adequate light to grow. If sunlight is not available, artificial lights can supplement natural light.

Below, I elaborate more on common light terms, different light levels, and the 5 light types for plants:

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Light Levels

The intensity of light plays a crucial role in the growth and development of plants. They influence photosynthesis – the process within a plant that converts light, oxygen, and water into carbohydrates (energy). Without adequate light, plants cannot manufacture the carbs needed, depleting their energy reserves, and eventually die. Unlike humans, plants cannot survive on a keto diet.

So, here’s where we talk about the different type of light levels and terms you’ll come across often:

1. Direct Light aka Full Sun. This can also be known simply as ‘Bright Light’. It’s when there is nothing blocking the light from the sun, whether it be trees, hedges, buildings, blinds, or even an overhead roof from outside.

2. Indirect Light aka Filtered Light. Any type of light that’s partially passing through a sheer obstruction is essentially filtered light for plants. Examples include a thin curtain or even an unruly branch you’ve been meaning to cut since last spring. It’s more common indoors, but it can also be observed outdoors if there are plenty of trees around your garden.

3. Low Light. This means very little to no direct sunlight is received by the plant. By contrast, it doesn’t necessarily equate to total darkness for the plant. There is some indirect light still, but it’s just enough for the plant to survive but not thrive. It could either be a case of no windows in the room, no natural light, or the plant is placed far away from the window. Typical low-light plants include Snake Plants and Cast Iron Plants.

If you’re interested in knowing more about Snake Plants and Cast Iron Plants, here are some articles that may fascinate you:

• Do Snake Plants Need Drainage Holes? The Truth You Need to Know
• 11 Best Unkillable Houseplants to Start Caring For
• Can You Put Indoor Plants Near a Heater? We Tested 19 Houseplants

4. Medium Light. This is when the plant receives plenty of indirect light, about 2 to 6+ hours daily. It can be through a shaded window or a few distance from it, allowing most indoor plants like Monstera, Fiddle Leaf Fig, Jade Plant, and Rubber Plant, to thrive in this condition.

Here are some related articles on Monsteras, Fiddle Leaf Figs, Jade Plants, and Rubber Plants you might enjoy:

• Training an Indoor Monstera to Climb – With Helpful Tips
• Are Terracotta Pots Good For Monsteras? – With Helpful Tips
• Do Monsteras Like To Be Misted To Grow Better?
• Why Do Fiddle Leaf Figs Get Leggy? & How to Fix It
• What Happens If You Cut The Top Off A Fiddle Leaf Fig? – With Helpful Tips
• Can a Jade Plant Grow Indoors Without Sunlight? – With Helpful Tips
• Do rubber trees have aerial roots? Yes! and people make living bridges with them!!

5. High Light. This refers to an environment when plants get direct sunlight shining through unshaded windows for 6+ hours daily. Mostly cacti, succulents, and flowering plants do best in these bright light conditions. But your best growers would be herbs and seedlings. But it does mean these areas are often warm, making plants dry out faster. Therefore, it’s important to check these plants more frequently and water when the soil is dry. 

Now, despite that though, our eyes are actually waaaaay too good at adapting to light changes that we can’t really tell whether the light we’re giving our plants is good enough. So, this is where you can whip out your smartphones and download apps that are Lux Meters.

As a general guideline, here are the lux measurements corresponding to the following light levels indoors: 

Note: The conversion factor used is 1 foot-candle ≈ 10.764 lux. Ftc used to be the most common illuminance measurement used in the US, but because Lux is becoming more widespread in most industries, it has quickly become the standard unit of illuminance instead. But both can still be used either way.

With that said, how can we tell what are the light requirements for each plant? 

Light requirements for plants vary based on their natural habitats and growth needs. So here are some common indoor plants and their light requirements:

Alright, now that you’re familiar with light terms and their typical measurements, let’s get into the various light placements you can position your plants in (Note: All windows in the following scenarios are considered unshaded with no obstructions indoors or outdoors, unless stated otherwise):

North-facing window light

When you place plants in this spot, it will only receive indirect light all day long. It’s very rare for direct light to stream through north-facing windows, especially in regions located in the northern hemisphere. The sun’s path doesn’t typically allow it, except possibly during the early morning or late evening during certain times of the year. What can I say – the sun doesn’t really shine where Santa lives, unfortunately. 

For those living in southern parts of the world, it might be bright enough for some medium-light plants to grow in but most won’t thrive so expect slow growth.  Despite that, it still provides a steady source of indirect light throughout the day, without the intensity and heat associated with natural light. So it’s best to keep low-light plants in this placement instead.

East-facing window light

Most medium-light indoor plants will thrive in this area, where they’ll receive direct light in the morning and indirect light in the afternoon. How does that work, you ask?

Well, when the sun rises, the morning light streams through the east-facing window. It’s bright but not as intensely hot as the midday sun, making it suitable for a variety of plants. This is especially beneficial for indoor plants with delicate leaves that’ll burn when exposed to glaringly hot sunlight. By afternoon, the sun would be well on its way down the opposite side, leaving only indirect light casting through the window.

But if the window is shaded by a curtain, a tree, or an overhead roof, it’s considered as indirect light as it’s blocking most of the direct sunlight. 

South-facing window light

This is the prime spot to place high-light plants that thrive in full sun because direct light will shine all day long through the windows. It’s especially helpful for flowering plants like Hoyas and Geraniums. However, excessive direct light can be harmful as well. When a plant gets too much direct light, the leaves can become pale or scorched, turn brown, and die.

The only way you can achieve indirect light from a South-facing window is by placing your plants 2 to 6 feet back from, or 1 foot to the side of the window. Alternatively, you can add a translucent curtain too. It’s less harsh on the more medium-light thriving plants while still giving them the benefit of an eternally bright room to grow in.

West-facing window light

It’s best to place a mixture of high- and medium-light houseplants in this area because it’ll receive indirect light in the morning then direct light in the afternoon. Sounds familiar?

The morning light is often bright but indirect because the sun is rising in the opposite direction of the window. But as the sun slowly descends from its highest peak during mid-day, intense direct light will enter the West-facing window. It is almost as strong as the light coming from a South-facing window. For some medium-light plants, this may be too much for them. Be sure to place a curtain over the window in the afternoon or move the plant a few distance away to keep it from being scorched.

Plant Lights

In this section, we’re talking about artificial lights, otherwise more commonly known as ‘grow lights’. For those who can’t get natural light in their homes, whether it’s because you live in the city, or in the basement, these plant lights are your best alternatives. But before that, a quick introduction into understanding light spectrum:

Light Type | Spectrum

The light spectrum is composed of red, orange, yellow, green, blue, indigo, and violet light. Of all those, plants specifically use the red light and blue light. Depending on the growth stages of a plant, a specific light is used to encourage more development:

• Blue light is more suited for starting seeds and leafy greens, as well as non-flowering house plants.
• Red light is used for promoting bud formation in flowering and fruiting plants.
• White lights or mixed/balanced light bulbs can be used at any stage of growth for most plants.

If you’re primarily growing flowering or fruiting plants, another factor to consider is light duration. This is called photoperiod, which is the number of hours of light a plant needs per 24-hour period. But because it’s more fiddly to grow these plant types indoors, most people don’t bother and focus their effort on maintaining their leafy houseplants instead.

But if you’re thinking of using plant lights, LED lights may just be the answer for you!

LED Lights

Light Emitting Diodes (LEDs) are a popular choice for indoor plant growth. They are energy-efficient, durable, have a long lifespan, and emit low heat, making them ideal for plant development. As grow lights, they are available in specific light spectrums to encourage optimal results for different plant growth stages. You can find out more in this Microgreens article where we discussed LEDs & light spectrums!

Frequently Asked Questions About 5 Types of Light for Plants:

Can I use normal light for plants?

Normal light can be used to grow plants but it will not encourage optimal growth. Examples of such include office lights, fluorescent lights, and floor or desktop lamps. This type of indoor lighting often lacks the full range of light spectrum needed for photosynthesis when compared to specialized grow lights. 

What type of light is needed for growing plants?

Grow lights that emit red & blue light are needed for growing plants. But they also grow well under full-spectrum light, which mimics natural sunlight and includes all colors of light (red, blue, green, yellow, and beyond). Specific types of indoor grow lights include fluorescent bulbs and LED lights.

What type of light is best for aquarium plants?

LED or fluorescent bulbs with full-spectrum light is the best type of light for aquarium plants. Not only will the plants grow well, but the overall lighting adds to a more balanced aesthetic to the entire tank. But you can also experiment around with other lighting according to your preferences.

What type of light is suited for Spider plants?

Spider plants do best in bright, indirect light, i.e. Medium light. They can tolerate low light conditions, but their growth may be slower. On the other hand, direct sunlight can scorch their leaves, so it’s best to keep them in a spot with filtered light.

Will any light work for plants?

Any light will work for plants but only a few will encourage their best growth. So, choose suitable grow lights that will boost your plant’s development. As mentioned previously, plants primarily need the blue and red range of the light spectrum for photosynthesis. Blue light promotes vegetative growth, while red light encourages flowering and fruiting. This is why standard incandescent bulbs or even regular indoor overhead lights are not enough as they only have a very limited light spectrum range.

References:

1. Colorado State University Extension. (n.d.). Interior plants: Light. Retrieved August 8, 2023, from https://planttalk.colostate.edu/topics/houseplants/1352-interior-plants-light/
2. Gardening Solutions, University of Florida IFAS Extension. (n.d.). Light for houseplants. Retrieved August 8, 2023, from https://gardeningsolutions.ifas.ufl.edu/plants/houseplants/light-for-houseplants.html
3. Johnson County K-State Research and Extension. (n.d.). Lighting options for seeds. Retrieved August 8, 2023, from https://www.johnson.k-state.edu/lawn-garden/agent-articles/vegetables/lighting_options_for_Seeds.html
4. LibGuides at University of Southern Maine Libraries. (n.d.). The importance of light. Retrieved August 8, 2023, from https://libguides.usm.maine.edu/c.php?g=1254198&p=9186843
5. Missouri Extension. (n.d.). Lighting for indoor plants. Retrieved August 8, 2023, from https://extension.missouri.edu/publications/g6515
6. Oklahoma State University Extension. (n.d.). LED grow lights for plant production. Retrieved August 8, 2023, from https://extension.okstate.edu/fact-sheets/led-grow-lights-for-plant-production.html
7. University of Maryland Extension. (n.d.). Lighting for indoor plants. Retrieved August 8, 2023, from https://extension.umd.edu/resource/lighting-indoor-plants
8. University of Minnesota Extension. (n.d.). Grow lights for starting seeds. Retrieved August 8, 2023, from https://extension.umn.edu/yard-and-garden-news/grow-lights-starting-seeds
9. University of Minnesota Extension. (n.d.). Lighting for indoor plants. Retrieved August 8, 2023, from https://extension.umn.edu/planting-and-growing-guides/lighting-indoor-plants
10. Washington State University Extension. (n.d.). Houseplants tip sheet 15. Retrieved August 8, 2023, from https://extension.wsu.edu/king/houseplants-tip-sheet-15/
11. Weisenhorn, J., & Hoidal, N. (2020). Lighting for indoor plants. University of Minnesota Extension. Retrieved August 8, 2023, from https://extension.umn.edu/planting-and-growing-guides/lighting-indoor-plants