How Much Light Do Houseplants Need?

The Key Word is Light

What I am about to say today everybody knows and understands. Light is essential to life on Earth!
It is all about energy transfers, or as a direct quote from Lion King’s musical, “The Circle of Life.”
To understand this, you need to understand photosynthesis. This is best described in a chemical formula where simple chemicals in abundance on planet Earth are combined to produce sugars that power life as we know it.

Carbon Dioxide + Water combined with light, manufacture glucose + Oxygen.

Glucose is the fuel of life, and Oxygen is the breath of life.

In my last blog, I spoke about Oxygen and its importance for cell respiration. Today I want to talk about your houseplants, the fuel that powers them, and the importance of placing your plants in the correct place within your house for them to thrive.

The above formula is an oversimplification, and an awful lot goes on within the leaf to make this happen; however, it is the basic building block. LIGHT is the key!

Thriving in the best position

Tropical houseplants, by and large, inhabit a very overcrowded environment in their natural state. Therefore, shade is an important part of their life. If you are growing below the forest canopy, I can assure you there is not much light. The plant may get varying amounts of light daily depending on where the sun is in relation to the plant. There is a plant in the wild for every situation on planet Earth with the exception of the poles. If it cannot live where it germinates, it dies, and another species takes its place. It’s called natural selection. If that plant thrives, it makes its home there and will inhabit situations similar to the original plant in that area.

What is the significance of this?

Well, in the average house, there is a place that is more or less identical to the conditions in which most tropical plants can thrive. All we have to do is find it. Tropical plants work in houses because most live in the shade, and our homes replicate the forest in that respect.

As growers, we shade our plants to acclimatise them to household conditions because, in many cases, too much light harms the leaves. In addition, too much light interferes with the chemical processes, and if it is too harsh will stop the process entirely.

The same is true for too little light. If there is insufficient light for the plant to maintain itself, it reacts by removing nutrients from its leaves and redistributing them to areas where the plant benefits from them. This way, the plant saves energy. This is called the compensation point. In other words, a leaf must contribute more energy than it uses to benefit a plant. If it falls below that point, it is discarded.

This explains why when a new plant is introduced to the house or a houseplant is moved to a different location within the home, the lower leaves turn yellow and eventually fall off.

A happy plant

If you use this as an indicator, the plant actually tells you whether it is happy or otherwise. If no yellow leaves appear, you can be sure all light aspects are satisfied. It is worth noting that overwatering can cause the same yellowing symptoms, but you should know if that is a problem by just looking and feeling the compost.

Other factors to consider

There is another factor you need to consider when placing the plants within your house, especially when relying solely on natural light. The natural day length changes throughout the year. So, all is well in the summer because the plant is thriving, but by mid-winter yellow leaves are starting to appear. If it’s not overwatering, it will likely lack of light. This can be rectified in one of two ways.

Move the plant to an area with more light. Moving towards a window will usually correct this. Or by shining a light, ideally a spotlight that makes a feature of the plant, and as a byproduct, the plant receives light that helps it maintain itself.

In my next blog, I will discuss the positioning of houseplants within the house so that you derive maximum pleasure from them.

Written by MIKE OPPERMAN