Can You Completely Replace Sunlight With Fertilizer?

Fertilizers and sunlight have one thing in common, which is to help plants thrive. Without these two sources, plants may begin to wither and die. However, the question remains: can fertilizer be a plant’s only source of nutrients? 

You cannot replace sunlight with fertilizer because plants cannot survive without sunlight and water. Fertilizer is only a nutrient additive for plants. If plants need an alternative to sunlight, gardeners can incorporate artificial lighting. 

Continue reading this article to hear more about what plants need to survive. I will also talk in-depth about why you cannot replace sunlight with fertilizer. 

Fertilizer Is Not a Replacement for Sunlight

If you’re relatively new to gardening, fertilizer might be something that intrigues you. Many gardeners have had tremendous success while using synthetic and organic fertilizers. Plants take well to fertilizer like a supplement to grow big and strong.

However, the nutrients and additives that fertilizer provides to plants cannot replace sunlight. Sunlight and water are the two ingredients necessary for a plant’s survival. 

Fertilizer is food for plants that can help plants grow strong and fast by providing easy access to necessary nutrients: 

  • Nitrogen 
  • Phosphorus 
  • Potassium 
  • Iron 
  • Boron 
  • Magnesium 
  • Calcium 

If sunlight were absent, plants would not grow at all. The fertilizer’s nutrients must interact with the plant’s photosynthesis process for growth to happen. 

Why Do Plants Need Sunlight and Water To Survive?

Like people, plants need specific nutrients to survive and thrive. For plants, water and sunlight happen to be those necessary ingredients. 

Plants need sunlight and water to survive because they use these ingredients for photosynthesis. Without the process of photosynthesis, plants will not grow or blossom, and they may begin to wither and die. 

Plants use water and sunlight in the process of photosynthesis. It is essential for plants to always have a light source near, even if that source is artificial. Light is converted into energy during the photosynthesis process just as water and oxygen are. 

Some plants can survive in natural terrain that does not receive sunlight for long periods. These plants will not grow though until they receive light. For water, this is also true. Some plants can last long periods without receiving water. 

On the other hand, many plants in the world require water and sunlight every couple of days, if not every day. 

What Can Be Used To Replace Sunlight?

Sunlight is a necessity for plants, which we all now know. The good thing is that there are specific ways to replace it if your plants are indoors and not receiving enough exposure to natural sunlight. 

You can use artificial lighting or a sun lamp to replace sunlight, but this will not solve your lack of sunlight entirely. Most plants need a natural light source as often as they can to thrive and grow. 

Artificial lighting is a solution that many like to use and is effective for the most part. Unfortunately, it does not compare to the benefits of having actual exposure to the sun. Hower, if you decide to get one, be sure that it is high-quality and fits your plant setup.

How Long Can Plants Survive Without Sunlight?

Light is essential for plants, just as it is for people. It can make a significant impact on the growth and production of a plant. Because of this, plants cannot thrive very long without a light source. 

Plants can survive without sunlight for up to 20 days, depending on the species of plant. Some plants, however, can only last 4-5 days without sunlight. After that, they may begin to show signs of decay or lack of growth. 

Certain plants thrive in certain regions because of the weather they are exposed to. The same concept applies to indoor and outdoor plants. Gardeners and plant owners can research their specific plants to determine how often their plants need sunlight. 

Additionally, some plants may be considered “low-light plants” while others are not. This can help determine how often or how much light exposure a plant needs. 

Here are some examples of low-light plants: 

  • Snake plant 
  • Pothos 
  • Cast Iron Plant 
  • Chinese evergreen 
  • certain types of succulents 

There are other plants that can thrive in the shade but still need bright light near. Here are a few of them: 

  • Lamium 
  • Astilbe 
  • Digitalis 
  • Euphorbia 
  • most succulents 

Meanwhile, outdoor plants usually need high exposure to sunlight as many know. Here are a few common ones: 

  • Lavender 
  • Yarrow 
  • Bee balm 
  • Hibiscus 
  • Sunflower 
  • Geranium 

Does Sunlight Affect Fertilizer? 

Sunlight is vital for a plant. It can make or break the growth that occurs. Fertilizer, however, is not necessarily reliant on sunshine to be effective. 

Sunlight does affect fertilizer when it has already been applied to a plant. The more sunlight a plant receives, the quicker fertilizer will work. Fertilizer, however, is influenced more by exposure to moisture. 

As previously stated, fertilizer is food for plants. When fertilizer comes in contact with moisture or water, it begins to take effect and sunlight will interact with it. However, a fertilizer that is in a bag or not in contact with a plant will not be affected by sunlight. 

On warmer days, it is best to not fertilize your plants. Warm weather and heat can create immature growth in your plants that may negatively affect their health. When fertilizer and lots of sunlight are active at the same time, a strong reaction takes place. 

All in all, sunlight does not affect fertilizer alone. But, it can impact how fertilizer works, especially if it is warm out. 

Plants Do Not Need Fertilizer To Grow 

When plant owners begin to care for their plants, many think that fertilizer is necessary. However, this is not always the case. Your plants will tell you exactly what it needs to grow and flourish. 

Fertilizer is a plant food that helps plants thrive in many ways, and it is highly recommended. But, plants do not need fertilizer like they need sunlight. If plants have access to sunlight and water, they are able to grow. 

Unfortunately, sunlight is not always pristine, and neither is water. Due to this, fertilizer is beneficial. It can provide plants with precisely what they need to grow. A lot of times, fertilizer can also give plants immediate access to the nutrients they need. 

Photosynthesis is the most critical part of a plant’s life, and they need nutrients to go through that process. Fertilizer, in a way, is an additive that helps guide plants along with the process of their own growth. 

Is Soil Necessary for Plants?

It would seem that every plant needs to have soil surrounding its roots for it to grow. And soil is a helpful additive that can assist plants with their growth. However, soil is not the only ground substance that plants are rooted in. 

Soil is not always necessary for plants but is a highly recommended material to use when planting your plants. Plants require many nutrients to grow and survive, and those nutrients are in the soil. Without the nutrients that plants need, they might not be able to grow. 

Soil is one mixture that has many nutrients. And as many know, fertilizers and soil contain the prominent three ingredients that plants need to grow, which are referred to as N-P-K: 

  • Nitrogen 
  • Phosphorus 
  • Potassium 

There are also other mixtures and ways that plants can receive those nutrients. Potting mixes are a great option. As long as a plant has the essential nutrients it needs, it does not need soil. Here are a few of them: 

  • Carbon 
  • Hydrogen 
  • Oxygen 
  • Sulfur 
  • Calcium 
  • Magnesium 
  • Iron 
  • Boron 
  • Copper 
  • Nickel 
  • Zinc 

All in all, if your plant receives the nutrients it needs, it can thrive and blossom. Therefore, if your potting mix lacks some essential nutrients, you can supplement it with fertilizer.

Final Thoughts 

Sunlight is one of the most valuable factors for growing a plant, and fertilizer can help plants grow big and strong with the many nutrients it provides. However, fertilizers cannot completely replace sunlight because they have different functions in a plant’s life and growth.

If you have a plant that you are seeking to grow, do your research online and find out precisely what it needs. Surprisingly, plants can find a way to thrive even in unique circumstances. 

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.

Recent Posts