Indoor plants and natural light

Light plays an essential role in the development and upkeep of your plant. How much is enough?

picture by Alexey O

A plant can only make the food it needs to survive and grow when it receives light. Without light, its most important metabolic process, called photosynthesis, cannot occur. This process takes place in small green cell organs called chloroplasts. Photosynthesis is a process in which your plant takes water and carbon dioxide and turns it into sugars and oxygen with the help of sunlight.

Because sunlight is such an important factor in the plant’s metabolism, it is crucial to expose your plant to the right amount of sunlight. The optimum is different for every plant species, and depends on how well the plant is adapted to certain light conditions.

Of course, artificial light is an option that is becoming increasingly affordable. In the past, grow lamps were expensive and inefficient, drawing a great deal of power which made them expensive to use.

Nowadays, however, the increasing use of efficient LED lights is making grow lamps a viable alternative for people whose residences do not receive much sunlight, or during the darker winter months. We will be providing a deeper look at artificial light and plant care in another blog post coming soon!

Location, location, location

To find the right spot for any plant, first you need to observe how much natural light comes into your space. This depends mostly on the orientation of your windows*, but also on whatever can block or filter the sunlight along its way. For example, bright light can be blocked by trees, or filtered by window decoration.

The next step is to decide where you want to place a plant. Check out the amount of light that falls on this spot – you don’t need to measure it, just have an understanding of how many hours of light it receives and how direct or intense it is. Take this amount of light into consideration when choosing your new plant. Keep in mind that artificial light rarely has an impact on the amount of usable light for a plant, unless you use the aforementioned special growing lamps.

*Window orientations described in this blog post apply to the Northern hemisphere. In the Southern hemisphere, the orientations will be reversed.

Low-light Plants

Low-light plants don’t need a lot of light and will do great in the windowsill of a north-facing window, but also up to a few meters away from a west- or east-facing window. Some examples are Calathea plants and Asparagus but also most ferns. Find more examples here.

Medium-light Plants

These plants are most suitable for east- or west-facing windowsills. They may tolerate a few hours of direct sunlight, but not for too long as their leaves can get burned. If you have a south-facing window, place the plant more than a few meters from the window to prevent sunburn. You may already have one in your home – Monstera and Begonia are both medium-light plants that are extremely widespread, but you can find more suggestions here.

picture by Henry & Co.

High-light Plants

These plants love bright light, but will burn when they receive too much direct sunlight. Place these plants a few meters away from a south facing window. Some of them will also be happy in east– or west-facing windowsills. The ever-popular Ficus is a great example, as are banana plants. You can find a more complete list here.

Direct-light loving plants need a south facing window, and a few hours per day with direct sunlight or a grow lamp to thrive. In northern climates there may not be enough natural light all year around to support your plant so choose the position carefully. Cactus are an obvious example of a plant that needs direct light, but so are kitchen herbs such as Basil and Thyme! From succulents to carnivorous plants, there is a surprising array of plants that thrive in direct light.

picture by Demi DeHerrera

Symptoms of lighting problems

It usually takes a few weeks for your plant to adapt to a new place, so be sure to monitor your plant for a while to see if it remains happy or not. Your plant’s health is a sum of several factors (e.g. humidity, temperature), so you can never know for sure if light is the only problem. However, if you notice some of the symptoms described below, you may be able to make your plant healthy again by changing its location.

Too much light:

  • Yellow-brown, faded and limp leaves
  • Yellow or brown ‘sunburned’ spots on the leaves

Too little light:

  • Yellow/light green leaves
  • Pattern and/or variegation fade
  • Falling leaves
  • The plant starts growing strongly in one direction, with long, pale and weak stems. This process is called etiolation and occurs because the plant wants to grow desperately towards the light and invests all its energy in length growth, and not strength.

Natural habitat

If you do some research on your plant’s origin, it will become much easier to mimic its original environment and deduce the optimal care. To make things easier, we have already done research into the light requirements of different species for you – you can find a list of commonly-available plant species suitable for various light conditions here.

With the wide variety of plants currently available, we know it’s not always easy to pick the right plant for the right spot. A final tip: it can help to take into consideration the origin of the plant. If you know to what ecosystem a plant was adapted to flourish in, you can deduce the optimal growing conditions. Take cacti for example: they grow in deserts which puts them in bright and direct sunlight throughout the day. In contrast, a Calathea plant naturally grows in the undergrowth of tropical forests, where the canopy blocks most of the light. It has therefore adapted to thrive under low light conditions.

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