Does Plant Soil Need To Have Sunlight?

We’re all aware that plants need some degree of sunlight in order to flourish, along with many other things such as specific nutrients and water. However, many people may not realize that the sun affects the plant’s soil as well–although not in the way you might expect.

Plant soil, by itself, does not need to have sunlight. However, natural sunlight provides the soil with the nutrients it needs to support microbial growth and the microorganisms that thrive within it. Although it may not need it directly, it needs it to sustain life. 

The rest of this article will dive into the details of what exactly sunlight can provide for soil and whether it’s necessary for indoor plant soil. We’ll also touch on why soil temperature is especially important and what your soil actually needs to survive and thrive. 

What Does Sunlight Do for Plant Soil?

Giving your plant sunlight is widely known as one of the most effective ways to promote healthy growth. Along with a regular watering schedule, light gives life to our plants in ways that can’t be replicated. So, what exactly does it do for the plant soil?

Sunlight allows plant soil to stimulate the growth of vital nutrients your plant needs to survive. Without sunlight, essential organic matter wouldn’t be able to flourish, and this organic matter is one of the most important aspects associated with plant growth. So, while the soil itself will be fine without sunlight, it wouldn’t have the necessary nutrients to support the plant living within it.

Additionally, soil that has been well-watered and is frequently spritzed will inevitably soak up more sunlight than soil that hasn’t been exposed to light. If the soil is wetter, more sunlight can penetrate, more nutrients will grow, and your plant will be happier overall. This is how water and light affect plant growth: by working together to create an optimal environment for plant growth. 

Essentially, this means you can’t expect a plant to live for long in soil that hasn’t been exposed to some kind of light source. If you’re not watering it sufficiently, it won’t be able to absorb as much light, and it may be nutrient-deficient. Soil fertility may eventually be compromised, leaving you with no other choice but to replace it or use fertilizer to bolster the available nutrients.

Does Indoor Plant Soil Need Natural Sunlight?

Now that we know that plant soil needs sunlight to provide a lovely home for your beautiful plants, it begs the question: does the same go for indoor plants?

The answer to this question is: it depends. Sunlight is probably the most effective of light sources for indoor and outdoor plants alike, and it’s also the cheapest since it’s a form of renewable energy that won’t make your bills skyrocket.

In this regard, if you can give your indoor plant soil natural sunlight, this is the best option for you. Light is so vital for plant growth that if you don’t have an effective alternative, your plant will likely die. Putting your plant soil (and the plant itself) on a window ledge is a pretty simple and cost-effective way to give your soil the energy it needs to support growth. 

However, if you live in an apartment that doesn’t happen to get a lot of natural sunlight, or your window sills are already full of plant pots, you can use artificial light as an alternative solution. Artificial light can vary from special LEDs explicitly designed for plant growth to just placing a lamp over the soil. 

The options are truly endless when it comes to providing artificial light for your plant soil, so if you can’t offer plant soil natural sunlight, you can still have thriving indoor plants.  

You can read this article to understand more about giving indoor plants enough light to grow: How To Give Indoor Plants Enough Light To Grow

How To Provide Artificial Light to Your Indoor Plant Soil

When it comes to giving artificial light to plant soil, it’s best to use a system that allows light to penetrate across the entire plant, not just the soil. To be clear, if your plant doesn’t like too much light, you’ll need to place the light far enough away that it can benefit from it without drying up the plant. 

To provide artificial light to your indoor plant soil, it’s best to use either an LED lamp or a fluorescent light source. Using a fluorescent light will allow you to provide light on a budget, while LEDs tend to be more on the expensive side but will last longer. Whatever your budgetary priorities, either one will work just fine. 

However, in the race for efficiency and longevity, LEDs are efficiency superstars and will outlast most other forms of artificial light. They don’t give off too much heat (unlike incandescent light forms), and they won’t hike up your energy bill at the end of the month.

If you would like to explore your options for providing indoor plants enough light to grow, check out my article: How To Give Indoor Plants Enough Light To Grow

Does Soil Temperature Matter?

So we’ve established that sunlight (or light in general) is pretty crucial for any kind of soil that intends to support life. So does the temperature of plant soil matter, too? You might be surprised to learn the answer, since most people tend to think of light and water as the two most essential components of growing plants. 

It turns out that soil temperature does matter, at least to some extent. The natural processes that occur within healthy plant soil tend to thrive over certain temperatures, and soil naturally retains heat from a light source to save it for a rainy day. This might even be why, if you stop providing light for your plant, it won’t die immediately because the soil has a storage of heat that allows those natural processes to continue for a while. 

That extra energy it provides from its heat storage encourages microbial growth even when the light is removed. So, soil temperature does matter, and the amount of light you feed your plant soil will allow it to provide life to its plant even if a light source isn’t immediately available.

What Does Plant Soil Need?

Your plant soil needs light and heat, but it needs other things as well. Since soil is the primary habitat for your plant, it needs to contain enough nutrients to support the plant. In order to give it nutrients, such as nitrogen, calcium, and phosphorus, among others, it will also need water. 

Water is the fundamental source of life for many things, not just soil. Humans, animals, and plants need it to survive, so it’s natural that your plant soil needs it, too.  

This is because your soil is meant to support living things other than plants – such as bacteria and fungi–and those things need water to survive just like any other living thing. 

Additionally, a good fertilizer is often necessary to boost your plant soil. You may not think this is necessary, and if your plants are surviving well in the soil without it, it may not be.

However, soil being continuously used over a few months often needs a little push to get things just right. Using a little bit of fertilizer can round off the whole process and make life much easier for your soil to get things just right. 

Lastly, organic matter–sometimes known as organic (or natural) fertilizer–can be helpful when it comes to boosting the life of your plant soil. If your soil is clay or sand-based, organic matter can enhance the way it drains the water, allow more air to penetrate the soil, and increase the development of healthy microbes living within the soil. This will only help your plant soil to become a thriving life source.

For example, this Earth Science Earthworm Castings Natural Fertilizer from has no added chemicals or unnecessary additives, making it an excellent choice for those looking for a natural way to boost soil productivity. Those tiny microorganisms in your plant soil will absolutely love this. As an added benefit, the worm castings will poke tiny pockets into your soil to allow air to pass naturally through. 

Final Thoughts

This article has given you a thorough overview of plant soil and what it needs to survive and thrive. It turns out that sunlight is pretty essential to the soil if it’s being expected to generate life, so make sure you give your soil the love and care you give to your plant since, without healthy soil, your plant has very little chance of survival.

Additionally, don’t forget to provide your plant soil with everything else it needs to promote plant growth, such as water, fertilizer, and other raw materials that make it much easier to support the growing plant.

Alexander Picot

Alexander Picot is the principal creator of, a website dedicated to gardening tips. Inspired by his mother’s love of gardening, Alex has a passion for taking care of plants and turning backyards into feel-good places and loves to share his experience with the rest of the world.

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