Window position and sunlight: Australian guide
Why is it that some houses have such great natural light and yet others – despite a similar number of windows – are dim and gloomy?
There are several factors that determine how much natural light enters a room, but perhaps the most important to understand is the relationship between a window’s aspect and the sun’s natural arc. Understanding this relationship is essential in determining which space in your home will allow your new plant baby to thrive. And yes I know that fiddle leaf fig tree would look so darn west elm by that patterned occasional chair, but we have to give it a little more thought my darlings.
In Australia, the sun is always located to our north – due to our location south of the equator. It rises in the northeast and sets in the northwest, traversing in an arc between. In general this means that rooms with north directed windows get the most sunlight, while rooms with southern windows will receive little. East and west facing windows meanwhile enjoy direct sunlight for a part of the day respectively. We cover these relationships in further detail below.
The Australian sun trajectory and why it concerns you
Unfortunately for us Australians, advice on the interwebs regarding sunlight and window direction is almost always derived from wildlings – those poor souls north of the wall (by wall I mean equator, not Trump’s passion project).
South of the wall, things work differently.
Below is a work of art (don’t tease me) produced by yours truly about 3 minutes ago, designed to demonstrate the sun arc with respect to a dwelling/castle/manor/throne room. The first picture is the summer arc, and the second picture the winter arc. Why the difference? I’m not your third grade science teacher Janice.
As you can see, the sun is always to our north during it’s east to west traverse. In summer it’s position is higher in the sky relative to its position in winter. Let’s discuss what this means with respect to window aspect.
North facing window
The cream cheese of windows. They get twice the winter sun than east or west facing windows get, and you’ll usually have more than 8 hours of direct sunlight through these plant growing portals. Because the sun traverses high above in parallel to the window, the thermal radiation isn’t too harsh. Smooth and delicious sunlight. If you have living spaces with northern outlooks and lots of windows, lucky you. Any plant should thrive here provided it doesn’t need direct outdoor sunlight.
East facing window
You’ll get near direct sunlight through your eastern windows for the first half of the day – but don’t fear, it’s still a sleepy sun and it is soft and gentle. Plants enjoy it. If they are southeast directed though you’ll struggle getting much light. In summer you’ll get 6-7 hour’s worth of rays in total, in winter 5-6 hours. Maybe not enough for the greedy sun eaters. Go for plants that have low-moderate sun requirements.
West facing window
These cop the afternoon direct sunlight, and the sun is not happy to be going to bed. This light can be hot and harsh. Not for the faint of heart or easily burned. Same duration of light as the east facing windows more or less. Go for plants with moderate-high sun requirements that aren’t too fragile.
South facing window
No direct light in winter, and only a touch of early morning and late afternoon sunlight in summer. The long night. Not a great place for plants. Unless you’re up in Northern Australia – the closer to the equator the less pronounced this effect. You might get away with it there, so check your map. If you want greenery here, only low light tolerant species have a chance.
Window aspect and light: a case study
Let’s put these truth bombs into action.
You’ve just bought a new fiddle leaf fig tree. Bless your optimistic socks. Everyone (who reads Miss Pot Plant guides) knows that the fiddley fig doesn’t like being moved too often. So how do we find a good home where she will be happy to settle in for the long run?
Without having to buy a fancy light meter thingamabob, you instead whip out your iPhone and open compass. Right, now you know which way is which. In your room on interest, this allows you to understand which direction or aspect your windows face.
The second thing to do for advanced players – observe modulating factors. These include;
- External sunlight interruption; This could include trees, other buildings, window overhands, lattice etc.
- Contributory light; i.e a corner in your living room may have a western window and a northern window side by side. You wouldn’t place a fragile easily burned plant there..
- Room size; If you have northern windows but are placing the plant 15m back from them in your cavernous great hall, they mightn’t do you as much good
- Aspect variation; you don’t always get a perfectly east facing window. A window that’s facing a little northeast in going to get more light than a direct east facing window, and a southeast window less. Factor this in.
Once you’ve factored these things in, make a note of the light quality in the morning vs afternoon. This will help you confirm what you’ve deduced and also gain a better appreciation for total sunlight hours and quality for a particular location.
Secondly, you need to consider the optimal light conditions for your chosen plant. In our case, the fiddle leaf fig prefers bright indirect sunlight for at least 6 hours of the day. So, what are your options?
Well, we know we need a bright room with long duration indirect sunlight to satisfy our fiddle fig tree. In an ideal world we would have a brightly lit room with multiple natural light sources, and a position before a north aspect window or glass pane.
If this was unavailable, we would work through our options seeking maximal duration bright light that wasn’t too harsh. You would favour large eastern windows without external interference over western windows – which can burn our fiddle leaf fig – however a western window with some filtered light may be equally suitable. Each space has a combination of factors to be considered – as long as you understand the principles here, you’ll be fine.
What about rooms with multiple windows facing different aspects?
Here, you have to use your observational skill. If the room is well lit as a whole from multiple window sources, you’re in luck and can place your plant however you please (maybe not right on the western windows).
In some rooms however, whether it be due to external shading, room size , window size or aspect, the light is dim or patchy. In this case you’ll need to position your plant next to the window providing the closest match to the type of light desired. Or find another room Janice.
Tips if your window sunlight sucks
If you have a spot with great light and you like the position – but find your plant is getting a little baked – either move the plant a little further from the window or pop down to your local homeware store and get some of those thin wispy curtains that do more to soften light than block it.
If you have a room that’s just too dark, it gets harder. Either find a new room for your plant, or you’re down to three choices.
A) Place the plant in conjunction with a grow light. We will explore this in depth in another article.
B) Use a rotation schedule. Move your plant whatever location indoor or out that provides ideal lighting conditions – for a few days a week, or a week / month – whatever is necessary to stave off death. This is risky however – some plants don’t appreciate the back and forth. And don’t expect the plant to thrive, rather merely survive. A good compromise if you have a mature feature plant located in the house for aesthetics, but insufficient light.
C) Are there any modulating factors you can control? Remove a blind? prune a tree blocking light? Knock out a wall?
Ultimately, it makes more sense to accept your light for what it is and pick a plant that won’t be a jerk about it.
- The quality of light within a room is a function of the number, size and directionality of your windows, combined with modulating factors
- Predicting the intensity and duration of light based on your window layout is important for plant positioning
- In general, northern windows capture a high volume of good quality sunlight
- In general, southern widows get little direct sunlight and can support low light shade plants only
- Eastern windows get soft morning sunlight, the amount of decreases if the window is southeast directed
- Western windows get strong afternoon sunlight, which can be too harsh for some plants
And thats a wrap! I hope this guide was helpful to you. If you found it useful, please leave a comment! Or if you have any further questions or interesting advice to add, please share!