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What is bright indirect light? And how do you identify if you have it or not?

Bright indirect light is probably the most preferred type of light for the majority of our houseplants, but how can you tell if you have it or not? When you have houseplants suddenly the amount of light you get in your home becomes more of a big deal than it had previously been, I mean, it is a matter of survival for those plants! You start to hear things such as 'those are low light loving plants', 'this plant needs bright indirect light', 'oh that plant will handle medium light levels', but what does all of that mean? And don't get me started on those little images you get as 'care instructions' on your plant's pot when you purchase it. It can sound like nonsense when you first start out in the world of houseplants, because light is light, right?!

Whether you have one modest Cactus, you're a collector of Begonias, you're just dipping your toes in with a couple of houseplants you picked up on your latest trip to Ikea or you have a full indoor jungle going on, having the knowledge of what amount of light you get in your home and the light preference of each of your plants will be beneficial for your plants survival and their ability to thrive.

A little side note, this blog post is written for those individuals who are in the northern hemisphere. This is important to note as I will be discussing different window positions in relation to the sun. I suppose, if you're in the southern hemisphere you could flip what I say and work the opposite way around, my south will be your north!

In my journey so far as someone who has gone from having a few houseplants around the apartment to someone who collects houseplants and the living room is becoming a mini jungle, I've heard light being discussed in a lot of different ways and it can be really confusing. So I'm going to try and make it slightly less confusing now, hopefully, and then even less confusing later, again, hopefully!

I will admit, at this current moment in my plant collecting adventure, I'm not too worried about thoroughly understanding the science behind light measuring. However, I have been doing some research for the purpose of this blog post and I thought I would share what I've learnt with you all, and then move on to a more simple way of looking at how much light our plants are getting.

Light (or lumens - the measure of light visible to the human eye from a light source) is often measured in foot-candles and lux; there are other forms of measuring light but I don't often hear them being discussed, so I'm not about to research the differences there (sorry).

1 foot-candle = 10.76 lux

Now, if I were going to start measuring my light in this way and using this fancy light measuring lingo, I would go with the foot-candles option, because 1) it creates a cute imagery in my head and 2) I find the smaller numbers easier to manage in my lil mind.

Lets start by thinking about plants that are outside, they could be getting anything up to and beyond 10,000 foot-candles during the day (that's a lotta light!). The plants outside could be getting up to 50% more light than our plants inside.

So, thinking about our houseplants inside; if they're positioned on a window sill in a south facing window, they will definitely experience some direct sun light, they will get between 4000 and 6000 foot-candles (that's roughly 43,040 and 64,560 lux), and that number is only when the plant is getting full sun (like, the sunlight is hitting the leaves of that plant!).

If the plant does not receive any direct rays from the sun, but is able to see the sky, it will be getting bright indirect light. This will measure between 400 to 800 foot-candles (4304 to 8608 lux). If plant is further back in a room, away from a window, it could be getting anything between 50 to 150 foot-candles (538 to 1614 lux) throughout the day.

Bare in mind that the position of your window will play a large role in how much light your plant is getting. If a plant is sat in a north facing window and can see the sky, that does not mean it will be getting between 400 and 800 foot-candles, it is more likely to be getting around 150 to 200 foot-candles because that particular area of sky is further away from the sun than the sky seen from a south facing window.

Another thing to think about is the fact that the sun is in different positions in the sky throughout the year and therefore the intensity of the light will differ greatly between the different seasons.

A simpler way of measuring how much light your plants are receiving is the shadow test. This needs to be done on a bright sunny day otherwise you wont get accurate results.

Full disclosure, I took these photos on a very grey cloudy day. I used my grow light to help with creating these shadows so you could see what the shadows look like for reference for when you try this out. Please do make sure you do this on a sunny blue sky kind of day, your plants will appreciate it! Firstly, choose the area you want to place your plant, secondly, use something large and white on the floor or wall so that you're able to really see the shadow, perhaps a few pieces of white paper will do, maybe a white wall is next to where you want your plant to go or a white bed sheet could suffice. Next place your plant in position and see what the shadow looks like, you can also use your hand if the plant is too large or awkwardly shaped to keep moving around.

My Epiphyllum Anguliger aka Fishbone Cactus

In this photo you can see the clear outline of the shadow of my Fishbone Cactus. You can see the unique shape of its leaves in the shadow in full sharp detail. The sharper the shadow the more sunlight your plant is getting. If your shadow looks like this, it is likely that your plant is getting bright indirect light with bursts of bright direct light as the sun moves throughout the day.

My Epiphyllum Anguliger aka Fishbone Cactus

In this next photo, you can see the shadow is slightly less defined. It's fuzzy around the ages and harder to tell that it is the shadow of a Fishbone Cactus.

If your shadow looks more like this then your plant is likely to be getting a medium amount of light source during the day.

My Epiphyllum Anguliger aka Fishbone Cactus

In this final photo, you can see the shadow is much less defined. It's no longer identifiable as the shadow of a Fishbone Cactus. It could be the shadow of anything; some kind of Palm tree perhaps, a Cast Iron plant, a large spider flying towards you or maybe someone having a really interesting hair day.

If you're seeing this shadow then that plant will be getting much less light than most houseplants need to thrive, it will be in a low light area.

There are light measuring meters that you can buy if you're really interested in knowing how many foot-candles or lux your plants are getting in each area of your home but the majority of them come with a fairly hefty price tag, I've seen them ranging between £100-£600! I do own a three-way meter that measures light as well as moisture and pH, although I've never really used it to measure light, I figured I'd try it out for the sake of this blog post. As I've already said, the day that I'm writing this is an incredibly grey cloudy day, and the meter told me that my entire apartment was closer to the dark end of this meter than to the light (it does have a number scale, which says 0, 200, 500, 1000 and 2000 on it, I'm going to assume it's measuring foot-candles and not lux but I've misplaced the box it came in so may be incorrect there!). The meter did move slightly more to the middle when I went right next to my south facing window, so I'm guessing it isn't broken!

My three-way moisture, pH and light meter

I personally just tend to eye ball it when I'm measuring how much light my plants are getting. I live in an apartment with a large south facing window, I say window but its basically the entire wall as it is sliding doors out onto the balcony. The only other windows I have are two small north facing windows in the back of the apartment, so as you can imagine it's quite dark in those rooms and I only have low light tolerant plants back there. I sometimes experiment with plants that are less tolerant of low lights in those rooms and then I tend to regret that decision, whoops! I know that the plants in my living room and kitchen areas will be getting anything ranging from direct sunlight, bright indirect sunlight, medium light to lower light levels throughout the day. At the moment, it's coming to the end of winter and beginning of spring (hopefully, please?!) and I know throughout the winter the plants have had mostly low to medium light. They have managed ok though, there's been minimal casualties so far (really hoping it stays that way!) but come full spring and summer these guys will be getting loads of bright direct and indirect light - I can not wait, and neither can they!

I hope this post has helped you understand lighting a little bit better, the more you pay attention to the kind of light your space is providing, the easier you will find it to identify the type of light you and your plants are getting. I'm planning on doing a blog post on why light is important and the variety of plants that would be happy in different light areas, so keep an eye out for that one coming soon! If you do the shadow test let me know in the comments below or get in touch with me through the Instagram page. Thanks for reading!


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