An Easy Chart & Explanation to Determine Your Plant's Lighting Requirements
Posted on March 21 2021
We’ve all been there: there’s a specific place in your home you want to fill with a houseplant. You purchase the “perfect” specimen, place it in its new home, only to relocate it a few weeks later because it is withering away. You buy another plant, and the same thing happens. How can you determine how much light a plant needs? And how does that translate into your home environment? Check out this easy explanation and chart about how to fulfill your plant’s light requirements!
The Importance of Light Natural light plays a vital role in the life of your plant. They need it to produce pigment (chlorophyll) and for energy (through photosynthesis). Not enough light? You will end up with a weak, pale plant that is also likely overwatered because the roots aren’t growing enough to absorb moisture. It’s a pretty sad situation, no?
The Challenges of Window Placement If you are a directionally challenged plant parent, don’t despair. While understanding which direction your window is facing can be helpful, it’s not a fail-proof way to determine how much light your plant is receiving.
For example, what if a tree or building obstructs your brightest south-facing window? How can you determine the amount of light that is really hitting your plants? What if you have small windows or sheer curtains that block some of the light?
The Shadow Test & Plant Light Chart That’s where “The Shadow Test” comes in: it helps you determine the amount of light your plant is receiving in your environment.
Here's how to perform the Shadow Test:
- Prepare yourself by getting a large, blank piece of paper.
- At the brightest part of the day, place your paper vertically, facing the light source, at the height and location you would like your plant.
- Put your hand a few inches away from the paper.
- Use the Light Requirement Chart below to figure out what type of lighting your plant will be receiving.
Low Light An area that has Low Light will have a faint shadow, with little to no definition. You should not see your fingers, but you should see some type of shadow. Most likely, it will be an indistinct blob.
According to our Light Requirements Chart, your plant is probably near a North-facing window. This location will never receive any direct sun and is only suited to Low Light Plants, such as the Sansevieria, ZZ, and Parlor Palms.
If there is no shadow, that location is not suitable for plant life. While many Low Light Plants can survive for a time in no-shadow conditions, they will not grow. If you are determined to fill this spot, you have a few options:
- The Tag-Team: Rotate two low-light plants. Place one in a brighter location (bright indirect lighting would be most suitable for this method) and the other in the darker area. After two-to-three weeks, swap them out.
- The Summer Vacation: Many Low Light Plants will overwinter in shadier locations because they are not actively growing. During the growing season, relocate them to a brighter space or outdoors. During dormancy, place them in this no-shadow location.
- The Winter Vacation: There are a few plants out there that require more light during the winter months and lower lighting conditions in the summer. The Christmas and Thanksgiving Cactus require lower levels of light until a few months before blooming.
Keep in mind; you should never place your Low Light plant in a room without any windows. Only use the above methods in a room that receives some natural light.
An area that has Bright Indirect Light will have a weak shadow with a silhouette. You may have to move your hand andBright Direct Light can be beneficial for some plants, but it can also be harmful if they receive too much direct sun. If your plant is labeled for Bright Direct Light, but you notice its leaves are turning yellow or brown and crispy, it's probably getting too much direct sun. In that case, try moving it a few feet away from the window or place a sheer curtain between the plant and the window to diffuse the light.
Medium Light An area that has Medium Light will have a faint shadow with clear definition. What does this look like? You should be able to see your fingers and a defined shadow.
According to the Light Requirements Chart, your plant may be placed in a North-facing window or an East/West-facing window. However, it could also be placed farther away from a South-facing window or closer to a North-facing window.
Medium Light is suitable for a wide range of houseplants, including some popular ones like the Spider Plant, the Pothos, and the Philodendron.
High Light An area that has High Light will have a strong shadow with a crisp silhouette. What does this look like? You will see a clear shadow with high contrast and very defined edges.
According to the Light Requirements Chart, this could mean your plant is placed in a West or East-facing window that receives direct sun for several hours a day, or a South-facing window with filtered light for part of the day.
High Light is great for plants that need a lot of sun, such as succulents, cacti, and some tropical plants. However, keep in mind that not all plants labeled for High Light can tolerate full direct sun all day, especially during the hottest hours of the day. Be sure to check the specific light requirements for your plant species to avoid burning its leaves.
In conclusion, understanding the light requirements of your plants is crucial for their health and growth. By doing the Shadow Test and referring to the Light Requirement Chart, you can easily determine how much light your plants need and where to place them in your home. Remember to check your plants regularly and adjust their location if you notice any signs of stress or damage. With a little bit of patience and observation, you can create a healthy and thriving indoor garden.