Light Requirements - Outdoor + Indoor Plants
WHAT IS ASPECT:
Because of the way the sun moves through the sky, the direction in which your home faces plays a big role in the light available to your plants. This phenomenon is called aspect.
West and South facing yards will get roasted with much longer and hotter sun exposure than North and East facing yards. Unless there are large buildings or trees blocking the sunlight, the South side of a house will be exposed to sun almost all day long. The West side of a home will get afternoon sun, which is going to be hotter and more intense than the East side’s morning sun exposure. North sides of buildings tend to stay in shadow for most of the day. These aspect guidelines apply to both outdoor and indoor plants. If you have windows on the South or West side of your house or apartment building, you will get more light than on the North and East sides.
North, South, East, West, Definitions
This is where you can receive soft light consistently throughout the day. The light would be considered indirect. The windows never have sunlight coming through them. Rooms facing north tend to be the coolest rooms in the house.
The strongest rays of sun flow in the windows on the south side. Lighting in the south side is hot, especially in the summer. Bright warm light all day long. The light is also consistent throughout the day.
Great spot for morning light. Warm light in the mornings and cool in the evenings. The temperature will also be warmer in the mornings and cooler in the evenings.
The light is cool in the evenings and warmer in the mornings. Great afternoon light. The light is direct in the evenings. Direct sunlight stops shining through the windows by mid day on the west side. Windows facing east receive great light and natural sources of heat without being too hot.
6+ hours of direct sunlight per day. Full sun plants can take hot afternoon sun. They will start to struggle if they are not getting enough sun. Some signs of a struggling plant that is not receiving adequate light are: the leaves turn yellow or are pale green, the leaves are small, the plant has leggy or stretched growth, the plant can even stop growing or grow very slowly. If the plant flowers it might flower sparsely or not at all.
Part Sun/ Part Shade:
2-5 hours of direct sunlight per day. Part sun/shade plants still need some direct sun, but they do not want to be roasted in the sun all day long. They need some protection and will be ok in a shady spot as long as they get direct sun for part of the day. These plants tend to prefer morning sun and afternoon shade, but can take a bit of afternoon sun as long as it’s not all afternoon-long. Some part sun plants are okay in light shade or bright, filtered light all day instead of 2-5 hours of direct sun.
Ranges: If a plant says Full Sun - Part Sun, it means the plant is ok in both full sun and part sun conditions. Either way works! If a plant says Part Shade - Full Shade, then both part shade and/or full shade are okay for that plant.
Full shade plants do not want any direct sun exposure. They want to be under the cover of a tree or a shade structure all day long. Many of these plants grow on the forest floor or in shady canyons in the wild. If there must be some direct sun exposure, it should be kept under 2 hours.
Side Note - Depth of shade: Any area where direct sunlight is blocked can be considered shade. However, there are degrees to the depth of shade available. For example, if a tree canopy is very dense, it will provide deeper shade than if a tree canopy is more sparse. Sparse canopies allow filtered light to come through, which is sometimes enough for partial shade plants. Further, the distance of the plant from the edge of the tree canopy influences how light or deep the shade will be for that plant. However, if there is a solid shade structure that doesn’t let any light through, you can expect deep shade and should stick to full shade plants.
Direct light means that the sun is shining directly on your plant —there is nothing shielding your plant from the sun’s direct rays. If you are keeping plants indoors, it is rare that you will get direct light, as the roof is often in between the sun and your plant. However, if your plant is right next to a window and there is no awning shading the window, there may be a period during the day where the sun is angling directly at your plant. If you have this direct light condition, you will need to select indoor plants that can take direct light and not get leaf burn. Most direct light areas are on the south facing side of your house.
Bright Indirect Light:
Most indoor plants prefer bright indirect light. This means that although the sun isn’t directly hitting the leaves, there is still bright light available for the leaves to absorb. Remember that for many house plants, you are mimicking rainforest conditions, where they would be under a tree canopy receiving filtered light. If you can read comfortably in your room without straining your eyes at all, that is sufficient bright indirect light for many house plants. Most bright indirect light spots are the west and east facing windows.
Plants best in bright indirect light.
Medium Indirect Light:
Perhaps you want to place your house plant in a corner of the room away from the north facing window. It is possible to place your plant further from the source of light, but you will want to select plants that are tolerant of medium indirect light. Medium light describes light that you could still read in, but would strain your eyes a little. Most plants will prefer bright indirect light over medium or low, but many will still be able to survive and thrive in this condition. They may not grow as fast or flower as much as they would if they got more light, but they shouldn’t show any signs of stress due to light.
Low Indirect Light: Low light isn’t an ideal condition for most plants, but there are some that can tolerate it nonetheless. Low light would really strain your eyes to read in, and you would feel prompted to turn on a light. An example of low/dark light is a bathroom without any windows, and receives no sunlight at all. Plants growing in low light will grow very slowly and may never flower.