What Counts as Direct or Indirect Light for Houseplants: Overview

Light is an important factor for happy houseplants. It might be easy to figure out which spots are the brightest in your home as this is where you can see the sun shine through the most often. Though apart from these sunny spots, how to know how much light there is and if this counts as direct or indirect light?

An uninterrupted direct line of light between the light source and the plant is considered as direct light while indirect light is defined as light that either passes through or is reflected off a medium between the light and the plant.

Read on to find out which windows in your home are the brightest, how far away from windows you still get a decent amount of direct light for your indoor plants, and how to measure the light levels!

Direct vs. Indirect Light For Houseplants: Why Does it Matter?

Knowing what counts as direct and indirect light helps a lot to find out what place in your home fits which plant you have. Each plant type has different light requirements. If you want your plant to thrive, you best meet these requirements.

Once you have figured out what spots in your home get the most direct sunlight and what spots only indirect light, you are already a big step further to placing the right plants in the right spot.

The amount of light given at a certain spot does not have to meet a plant’s light requirements with 100% accuracy for the plant to do well. For most plants, it is enough if the light fits more or less unless you have very sensitive plants among your green houseplants (for example some types of ferns can be tricky but that’s not just due to light but mainly humidity requirements).

That said, let’s start with what direct and indirect light is:

What Counts as Direct Light?

Direct light is defined as light from the sun that hits the plant in an uninterrupted direct line. This means there is nothing in between the light and the plant.

If sunlight is filtered through the leaves of a tree outside or if light reflected through a mirror hits a plant, it is no longer considered direct light.

Good to Know: Not only sunlight can be a source of direct light. Artificial grow lights or any plant lamps indoors are also considered direct light. These artificial plant lights can be pretty strong sometimes and it is easy to forget that shade-loving plants shouldn’t be exposed to too much artificial lighting, either.

Want to know more about artificial lights? Read on in my post on how UV light works for plants and how to use it correctly!

Is Light Through a Window Considered Direct Sunlight?

According to physics, light through a window is not considered direct sunlight as the window reflects about 50% of the sunlight’s intensity. This means that plants standing outdoors are exposed to sunlight that is twice as strong as it is behind a window.

However, as far as indoor plants are concerned, sunlight through a window definitely counts as direct sunlight. The spots next to the windows get the most sunlight indoors.

Please also remember that even though the actual light intensity is weaker behind the glass, the glass itself heats up the space right behind it (like a magnifying glass). That means it can get quite hot on the windowsills when the midday sun burns through them.

Hence, the fact that light intensity decreases through a window doesn’t mean it becomes indirect light or that full-shade plants can be put there.

How Close to a Window is Direct Sunlight?

You might wonder whether your houseplants are exposed to direct sunlight just on the windowsills or if you can also put them a little further from the windows.

This depends a lot on the orientation of the window. South-facing windows are the brightest and sunlight is considered to be direct until about 2-3 feet (or 1 meter) away. East and West-facing windows only get sunlight half the day and as such, it is less intense. Still, direct light from these windows also reaches about 2-3 feet (or 1 meter).

On the contrary, North-facing windows do not provide much direct light at all as they usually don’t get any direct sunlight. These windows provide indirect light usually up to about 5 feet away (or 1.5 meters).

What Places in Your Home Have Direct Light?

Here’s a list of the spots in your home that usually get the most direct light:

  • South-facing windows are the brightest
  • East-facing windows have direct light in the morning
  • West-facing windows have direct light in the afternoons
  • Windowsills with no shades or curtains
  • Spots right in front of windows with no shades or curtains (suitable for taller plants standing on the floor or plants in hangers)
  • Spots on shelves that get sunlight through windows
  • Direct light through artificial lighting such as grow lamps
  • Spots beneath skylights

What Counts as Indirect Light?

Opposite to direct light, indirect light is light that either passes through or is reflected off a medium. The path from the light source to the plant is interrupted or indirect. In other words, something is in between the light and the plant.

Correctly speaking, light through a window is indirect light, too. Though as houseplants do not grow outside, this is the most direct light they get (after all, sunlight through a window is still intense enough to be called direct light).

Indirect light is therefore light through curtains, shades, blinds, the leaves of a tree outside, light reflected from neighboring buildings, or reflected from the surface of a lake.

Is Light Through Blinds Indirect Light?

Light through blinds or curtains is considered indirect light as much of the sun’s rays’ intensity is being reflected. Hence, even on a bright South-facing windowsill, plants do not really get direct sunlight if the curtains are drawn or the blinds lowered all the time.

As a general rule, you can always remember that direct light is light that passes through unobstructed windows. If there is anything in the way between your houseplants and the sunlight such as curtains but also trees outside, then it is considered indirect light.

What Places in Your Home Have Indirect Light?

Here are some examples of spots that most certainly only get indirect light:

  • East and West-facing windows get indirect light for half the day
  • North-facing windows usually only have indirect light
  • Windows with shades or curtains or otherwise obstructed windows
  • Windows that don’t get direct sunlight because of trees or buildings outside that provide shade
  • Spots further away from windows that the sun never directly shines on
  • Darker corners of your home
  • Spots behind bigger plants

Plant Light Meter Apps: Find Out How Much Light There Is in Each Spot

It is not easy to judge how much light there is in a particular spot of your home and for what plant it would be suitable. Luckily, there are plenty of apps that help you out with that.

Many plant care apps have light meters integrated. Holding your phone in a certain spot of your home, the light meter function will accurately measure the amount of light that spot gets. The apps then usually also give you recommendations on what plant types you could put there.

Want to try it out? Here’s a post with the 7 best free plant care apps including their pros and cons!

If you just want the light meter but not the plant advice, then there are also many simple light meter apps. These are some of the popular plant light meter apps:

Tip: Make sure to choose a PLANT light meter app as there are also many light meter apps for photography. Those usually come with different specifications and settings.

Plant Tags: What Do The Light Indications Mean?

When you buy a plant at a store, it usually comes with a tag or label that specifies its water and light requirements going from full sun to full shade. But what do the light requirements tell you about these plants?

Here’s a short wrap-up of what the indications mean:

  • Full sun: These sun-loving plants need at least 6 hours or more of direct sunlight. The more direct sunlight, the better they grow.
  • Half-sun/half-shade: These plants are all-rounders and can do with direct morning or afternoon sun combined with some hours of shade or indirect light. But make sure that these plants do not get too much intense midday sunlight.
  • Full shade: Those plants do not like direct sunlight at all and are best placed in spots where there is only indirect light or at the max some early morning or late afternoon sun.

Rule of Thumb: Full-sun and half-sun/half-shade plants can do with more or less direct light while full-shade plants are too sensitive to any direct sunlight.

Do LED Lights Work for Plants?

Inside a house, plants usually do not get as much natural light as they would outdoors and windowsills only have that much space to put plants.

There are alternatives to natural light though such as LED lights. Many regular LED lights will work for your plants and there are also specific LED plant lights you can buy. Find out here what LED lights work for plants!

What Water is Best for Houseplants?

The best water for houseplants is that which is healthiest for them. Rainwater contains the most nutrients, oxygen, and the least contaminants and it is the healthiest plant water you can find.

Not everyone can collect rainwater where they live. Read more in this post about what other great alternatives there are for plant water and how you can improve water quality easily.

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