Houseplants and Sunlight: What You Need to Know for Happy Houseplants

The part that I find the most complicated about houseplants is light.

I set out to figure this out for my home and learned some interesting things about houseplants and sunlight.

In addition to being the most complicated part about growing great houseplants, sunlight is also kind of the most important thing. No pressure or anything. It’s just the life of your plants on the line.

Ok, I’m kind of kidding, but it is important to figure out so that you can get the right plants in the right spot in your home and then you can keep an eye on them to make sure they are happy where you have placed them.

Why Do Plants Need Light?

I know you know that plants need light, but have thought about why they need sunlight?

Sunlight is their food. It’s what makes them go through photosynthesis so that they can grow and thrive and give off nice clean oxygen into your home.

So if a plant isn’t getting enough sunlight, it will have a hard time thriving. Just like any other living thing that isn’t getting the right amount and kind of fuel.

But it’s complicated because not every plant needs as much sunlight as others. That’s why you’ll see on your plants tag things like full sun, medium light, partial sun… Which is very helpful to know what the plant wants, but how do you know what you actually have in your own home?

How to Figure Out the Sunlight in Your Home

houseplants and sunlight - pretty pink/purple plant

One of the best books for beginner plant owners, How to Houseplant lists all of these things as factor for determining the sunlight in your home:

  • The direction your window is facing
  • The size of the window your plant will be near
  • How clean the window is (gasp!)
  • Where you live
  • Time of day
  • Obstacles outside your window

Umm, wow. That’s a lot. It’s a smidge overwhelming which is why sunlight can be complicated. Let’s tackle each point and see if we can make this less overwhelming.

Direction Your Window is Facing

The easiest way to determine which way your window is facing is to grab your phone and use the compass app and point it at the window.

The second easiest way is to see where the sun rises and sets and then determine East (rises) and West (sets) based on that. I went with the phone app method because I’m not Boy Scout.

houseplants and sunlight - pretty window with lots of light

And what do you think my app told me? It told me that the windows in the back of my house face North West and the windows at the front of my house face South West.

Of course it couldn’t be easy and just face North and South or East and West.

But it’s probably quite likely that your home will be something like mine and have windows that don’t face one of the cardinal directions. Let’s look at the cardinal directions and also at the differences that northwest and northeast can mean for your plants.

(Hemisphere disclaimer! These tips are assuming you are in the Northern Hemisphere. If you’re in the Southern Hemisphere, flip North & South)

North (and NW & NE) Facing Windows

If you’ve got a window that is facing North, you will not get any direct sunlight in that window. But that’s ok because low light plants will be very happy in this window.

If you’ve got a plant that wants full sun or partial sun, it will not like being in a North facing window.

If you’re like me, and you have North East or North West facing windows, then you will have sunlight coming in through that window either in the morning (if it’s North East) or in the afternoon (if it’s North West).

South Facing Windows

South facing windows are the holy grail of windows for plant lovers. They get the most sun and at the most important time of the day, late morning to mid-afternoon when the sun is strongest.

You want your houseplants that want full sun in these windows! Likewise, your low light plants won’t like it too much in this window.

One thing you do have to be careful of with south-facing windows in the temperature. These windows can get very warm and not all plants will be happy with that. You might need some ventilation or even a sheer curtain to help with all that direct sun.

West Facing Windows

Your west facing windows are going to sunlight in the later part of the day as the sun starts to head toward setting. That afternoon sunlight is not as strong as it is in the morning, but it is also usually warmer temps by that time of day, so keep an eye on the temperature for your plants in west facing windows.

Your sun-loving houseplants will be happy in a west-facing window, but you might need to consider partially closed blinds or a sheer curtain to help with the heat of the afternoon.

East Facing Windows

East facing windows get the first light of the day as the sun is rising. This is not going to be the super strong and hot sun that the west facing windows get and it’s probably going to be done shining in these windows by mid morning to mid day, depending on the time of year.

That means you shouldn’t have to worry too much about overheating in these east-facing windows.

What If You’re Not Putting Your Plants Directly in the Window?

You’re probably not going to want to put all of your plants directly in a window and that’s ok. There’s a quick test you can do to determine how much light a particular spot is going to get that plant seller Leon & George recommends:

Take a piece of paper or some other plane surface and hold your hand about a foot away from it, between it and the light source. If you can’t see much of a shadow or it’s very faint, you’re getting low light. In a medium light situation you’ll see a blurry or fuzzy shadow of your hand, and in bright light you’ll get a crisp clear shadow.

This a great idea for picking the perfect spot once you’ve purchased a houseplant, but knowing which way your windows are facing first will help you know what type of plant you should be bringing home in the first place.

Other Sunlight Factors to Consider

  • The Size of Your Windows – I am lucky because I have giant windows on the first floor of my home, so there is a large area for light to come through. This means that I’ll have more sunlight in any particular room than a room with smaller windows and more options for where I can place plants. Smaller windows are going to mean less opportunity for the sunlight to make it into your room and less options for where you can place the plants.
  • How Clean Your Windows Are – Well, I suppose it makes perfect sense that less light will be able to come through dirty windows, doesn’t it? So I did not include Windex on my list of indoor houseplant supplies, but apparently, I will need to invest in some and get those windows squeaky clean!
  • Where You Live – If you’re like me in the northeast of the US, then you know that certain times of year are going to mean less daylight (looking at you late fall and winter!).
  • Time of Day – Morning light and afternoon are not the same intensity. Morning is going to be less intense and hot then the afternoon, which is what makes knowing which windows face East and which face West so important.
  • Obstructions Outside the Window – You might not have thought about this one, but what is outside of your windows, like giant trees or bushes, might be blocking the sun! This is something to consider and if you’re concerned about obstructions, I would try the paper test mentioned above.

My Plan for My Northwest and Southeast Facing Windows

What I’ve learned is that I’ll have to sort of experiment with my northwest and southeast facing windows. I’ll put the sun loving plants in the southeast windows and any plants that will tolerate medium light near those windows, too.

For the Northwest facing windows, I’ll stick with the low light plant like Pothos and see how they do.

My house is currently surrounded by giant pine trees, too, so that is definitely an obstruction I need to take into consideration and I’ll be keeping a close on things to see if it’s a big problem.

Which brings me to the final tip:

Keep an Eye on Your Plants

All of the planning and figuring out about North and South and East and West and all of that is not as important as just watching what your plants are doing. Lots of plants can adapt eventually to different settings, so just keeping an eye on them and seeing how they are liking their environment is important!

Some things to watch for include:

Signs of Too Much Light:

  • Leaves that are curling, wilting or look scorched or brown
  • The plant new leaves are a lot smaller than the older ones

Signs of Too Little Light:

  • Leaves that are supposed to be variegated (combo or light and dark color on the leaf) are solid
  • The plant is “reaching” toward the window (move it closer!)
  • A flowering plant isn’t flowering
  • The plant isn’t growing
  • Your plant is dropping leaves and the new ones aren’t as plentiful

The Moral of the Story of Plants and Sunlight

There is a lot to think about with plants and sunlight, but, most importantly, you should pay attention to how your plant is doing. Watch for signs of the plant thriving or declining and then see what you can do to help the plant.

If you find you’ve got a plant that you just can’t get enough light to, you can always try a grow light!