The most important factor in plant care is light. Without proper light, plants cannot create the food they need to survive and thrive. Photosynthesis is the process of harvesting solar energy and converting it into chemical energy. This process can take place with natural sunlight or artificial lighting, but needs to be strong enough for plants to absorb the light.
How much light does my plant need?
Light requirements vary by species, but in general, you should always place your plant as close to a window as possible. It's tempting to place plants throughout a room to fill corners and spread out the greenery, but all plants prefer a view of the sky. Most plants require a range of light within 200 - 2000 foot candles.
How close to a window do I need to place my plant?
The distance to the window is determined by how many foot candles the plant will receive and the intensity of the light. In general, most plants want to be placed no more than 1-3 feet away from a window.
Does it matter which direction the window faces?
Yes! South and west-facing windows provide the strongest amount of foot candles and afternoon light (500-2000 foot candles). High light plants like cacti, succulents, bird of paradise, ficus, yucca and some blooming foliage (jasmine, hibiscus, etc), should be placed directly in front of a south or west-facing window. For plants that can take a lower amount of foot candles (200-800 foot candles), the light can be filtered using a sheer curtain or the plants can be moved away from the window by 2-3 feet.
North and east-facing windows provide a lower amount of foot candles (200-600 foot candles) with morning sun. Any plants placed near a north or east-facing window should be placed directly in front of the window (no more than 1-2 feet away).
How do I measure the light?
You can use a light meter such as the Dr. Meter Digital Lux Meter or an app on your phone.
What happens if my plant does not get enough light?
If your plant does not get enough light, it will first use it's reserved stores of food that it's created. This reserve may last weeks or months, but will eventually run out and will cause the plant to fail. Plants with inadequate light are also prone to root rot.
What are some signs that my plant is not getting enough light?
The plant can become elongated and leggy. The leaf color may fade. The spacing between the leaves becomes further and further apart and the new growth becomes smaller and smaller.
What can I do if I don't have enough light, but still want plants?
You can get grow lights! Grow lights are a great way to add supplemental lighting to your indoor environment and allow you to place plants in areas away from windows.
Is there anything else I need to know about lighting?
Yes! In addition to light, plants also need darkness. During the night, in the absence of light, plants go through a process called dark respiration during which they use the sugars produced during the day and add oxygen to create energy for plant growth. The temperature at night should be lower than the daytime temperature in order to complete this process.
For more information on lighting as well as a detailed chart of light requirements by plant type, we recommend visiting Houseplant Journal.