Plant Food vs. Fertilizer: What’s the Difference?

As someone who tends to a few potted tomato plants each summer, I’m far from a master gardener. In researching how to keep my plants healthy and producing, I’ve noticed much of the internet uses the terms “plant food” and “fertilizer” interchangeably. So are they really the same thing? The short answer is no.

What is Plant Food?

As we all know, plants make their own food through photosynthesis. After taking in carbon dioxide and water from the air and soil, a chemical reaction transforms the CO2 into glucose, a food source.

So when I see a package at my local nursery that claims it contains “plant food,” what does that mean? It’s actually not plant food at all. It’s standard fertilizer or soil additives containing additional minerals that help plants prosper.

What is Fertilizer?

Garden fertilizers enrich soil and provide plants with one or more vital nutrients, usually nitrogen, phosphorus, or potassium.

Fertilizers are not always intended to aid photosynthesis. They address specific plant problems or needs during periods of rapid growth or stress, or aid in overall growth. A fertilizer could contain nitrogen to promote leaf growth, or phosphorus for root development.

Which Do My Plants Need?

This ultimately depends on you, the gardener, and the clues your plants give you.

If you wish to promote a specific characteristic like root growth or leaf development, or replenish a specific nutrient in the soil, choose a fertilizer that targets those specific nutrients.  In contrast, if you need a broad mix of nutrients to maintain a healthy vegetable garden, go with a general plant food style fertilizer.

Applying Them to Plants

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Fertilizers and plant food come in a wide variety of forms, including liquids, granules and pellets. They can be synthetic or organic.

It’s common practice to apply plant food regularly throughout the growing season to maintain a steady supply of nutrients. On the other hand, traditional fertilizers are typically applied at specific times and in specific amounts, depending on the type of plant and its growth stage.

Before applying any type of fertilizer, read the manufacturer’s application instructions. Additionally, you should test your soil to determine its pH and any nutritional deficiencies.

How Long Do They Last?

In the soil, fertilizers can last for a week to several months. The duration varies depending on weather conditions, watering practices and the type of fertilizer.

Liquid fertilizers are only good for a couple of weeks since plant roots rapidly absorb its nutrients. In contrast, granule- or pellet-form fertilizers work for up to 90 days, because it must be broken down in the soil to provide nutrients to the plant.

Final Thoughts

There’s nothing wrong with adding nutrients to the soil via plant food or a traditional fertilizer. Choose the right one based on what your plants need and which minerals or nutrients your soil may be lacking.

Rudyard Kipling, the English poet, writer and Nobel Laureate, wrote in his poem The Glory of the Garden: “Our England is a garden, and such gardens are not made/By singing: — “Oh, how beautiful!” and sitting in the shade.” Sometimes our gardens, whether in England or here in the U.S., need a little help. Whether you do it with fertilizer or plant food is up to you.