Plant Food: Sunlight or Fertilizer?

How cool would it be if we humans could photosynthesize, or turn sunlight into food? Plants make their own food through a process called photosynthesis. Without getting too technical, plants take light energy (sunlight), carbon dioxide, and water and turn it into glucose (sugar) and oxygen. Without this chemical process, life as we know it would not exist. Plants are the foundations of our food web with us consuming plants and sometimes the animals that rely on plants for their survival. Oxygen is a byproduct of photosynthesis, which is required for us and other animals to breathe. We owe our very existence to plants.

Photosynthesis vs. Fertilizer

Besides the fact that plants are a crucial food source for life on Earth, they also function as sound/visual barriers, add aesthetic value to real estate, and reduce pollution and scrub the environment, hold down the soil and prevent erosion, build and heat our homes, even are used to develop medications. It behooves us to cater to plant light requirements and growing conditions. So before you grab the fertilizer and pesticides when you spot an unhappy plant, think to yourself – does my plant have the basics? Does it have the right amount of sunlight/shade or moisture requirements? Not all plant issues are caused by pest or disease; sometimes our lack of understanding and failure to meet the plants needs for survival leads to landscape failures.

Read Gardening Successfully in Florida’s Summer Heat for a comprehensive review of successful gardening.

You may be thinking, well what about fertilizer? Fertilizer is important to plant growth, but it should not be mistaken for plant food. Remember, plants make their own food through photosynthesis. Simply put, fertilizer provides the nutrients – like nitrogen, phosphorus, potassium, etc. – required for plants to grow, develop, and reproduce. You are not ‘feeding’ the plant with fertilizer. In fact, over fertilization can lead to disease/pest issues, water pollution, and yes, landscape failure.

Read more about photosynthesis here.

A closeup of a woman holding a magnifying glass to the underside of a large green leaf — Using a magnifying glass to look for pests on a green leaf in a school garden. 10-19-16.

Master the Basics

Most importantly, there are different sources of nutrients that plants use that are only available at a certain pH, or the measurement of acidity in the soil. Without the proper pH, some of these essential nutrients are in a chemical form that makes them ‘unavailable’ for the plants to absorb through their roots. Meaning, even though the nutrient is in the soil, the plant cannot benefit if it is not in a form it can process. It is critical to apply the correct amount of nutrients in the correct ratio as well. There are many options at the garden center, so make sure you turn the bag over and read the entire label before purchasing to make sure it is the right choice for the plants in your garden.

Read more about pH in the garden here.

This chart shows which nutrients are available to plants at a certain pH.

Luckily, the Fertilizer Fundamentals series breaks all of this information down. Check it out below.

Watch Dr. Whitney Elmore talk about fertilizer:

Have a question?

If you have any questions about gardening in Central Florida, please contact UF/IFAS Extension Pasco County at 352-518-0156. For more information on UF/IFAS Extension Pasco County Community Gardens, and how you can join one, visit http://sfyl.ifas.ufl.edu/pasco/. Supervising agent: Dr. Whitney Elmore.

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Photosynthesis vs. Fertilizer

Master the Basics

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