Is Fertilizer and Plant Food the Same? Unearthing Their Differences

Fertilizer and plant food – two terms that are often used interchangeably by gardeners. But are they really the same thing? The short answer is no. While both contribute to plant health and growth, there are some key differences between fertilizer and plant food. This article will explain what each one is, how they work and when to use them for your plants.

What is Plant Food?

First, let’s clarify what plant food actually is. Plant food is made by plants through the process of photosynthesis. Using energy from sunlight, carbon dioxide from the air, and water and minerals absorbed through their roots, plants are able to convert these raw materials into sugars, aka food. The sugars fuel the plant’s growth and other life processes.

So in short, plants make their own food. You can’t go to the store and buy plant food – only plants can manufacture it themselves. Anything labeled as “plant food” is actually fertilizer (more on that below).

What is Fertilizer?

Fertilizer is a supplement added to soil or water to provide extra nutrients that plants need for healthy growth. These nutrients include:

• Macronutrients – nitrogen, phosphorus, potassium, calcium, magnesium, and sulfur. Plants need large amounts of these.
• Micronutrients – iron, chlorine, boron, manganese, zinc, copper, molybdenum, nickel. Plants only need small traces of these.

The three macronutrients that plants need in the greatest quantities are nitrogen (N), phosphorus (P), and potassium (K) On fertilizer labels, you’ll see these three nutrients listed as the NPK ratio – this tells you the percentage of each nutrient in that fertilizer blend

Fertilizers can be organic (derived from plant and animal materials like manure or bone meal) or synthetic (manufactured chemicals). They come in different forms like liquids, spikes, and slow-release granules.

The Role of Fertilizer

Why do plants need fertilizer if they can make their own food? Simply put, fertilizer gives plants an extra nutritional boost.

Over time, soil becomes depleted of nutrients. As plants grow, they absorb more and more nutrients from the soil. Fertilizer replenishes the soil’s nutrient content so that plants have all that they need to synthesize food and thrive. It’s like taking a multivitamin supplement when your diet alone doesn’t provide all the nutrition you need.

Proper fertilization enhances plant growth by:

• Encouraging more extensive root and foliage growth
• Helping plants grow faster and bigger
• Boosting fruit and flower yields
• Bolstering plants’ disease resistance

Fertilizer also gives garden plants a competitive edge over weeds. Robust, fertilized plants soak up water and nutrients more efficiently, leaving less resources available for weeds.

When to Fertilize Plants

Follow these tips on when and how often to fertilize:

• For annual gardens and vegetable patches, work fertilizer into the soil before planting each spring. Side dress growing plants with additional fertilizer mid-season when growth is most vigorous.

• For perennial gardens, fertilize early in the growing season as plants come out of dormancy. Southern gardeners may need to fertilize a second time later in summer during peak growth.

• Fertilize container plants every 2-3 weeks during the growing season.

• For trees and shrubs, fertilize in early spring before buds break.

• Always water fertilizer into the soil thoroughly after applying.

Slow-release fertilizers only need re-applying every 6-8 weeks. Quick-acting liquid formulas must be re-applied more frequently, like every 1-2 weeks.

Over-Fertilization Dangers

It is possible to overdo it with fertilizer. Using too much or applying it too frequently can burn plant roots and foliage. Warning signs of over-fertilization include:

• Brown leaf tips and margins
• Yellow or wilted leaves
• Sparse foliage and stunted growth
• Root damage or rot

Over-fertilized plants often become weaker and more disease-prone. It’s best to test your soil first and follow product instructions carefully when fertilizing. If you do accidentally over-fertilize, flush the soil with water to wash away excess salts.

The Role of Soil pH

Before adding fertilizer, it’s important to know your soil’s pH. Soil pH affects how well plants can access and utilize nutrients, whether from soil or fertilizer.

Plants grow best in slightly acidic to neutral soil with a pH between 6.0-7.0. If the pH drifts too far above or below this range, fertilizer and soil nutrients become less available to plant roots.

Alkaline soil with a high pH prevents plants from taking up micronutrients like iron, manganese, boron, copper, and zinc. Acidic soil can have toxic levels of aluminum and manganese. Test soil 1-2 times a year and amend pH as needed.

Key Takeaways

• Plant food is produced by plants through photosynthesis using sunlight, CO2, water, and soil nutrients. Fertilizer is an additive that provides supplemental nutrition.

• Fertilizer replenishes the soil with nitrogen, phosphorus, potassium and other essential nutrients plants require to synthesize their food and achieve healthy growth.

• Over-fertilization can burn plants. Always test soil first and follow product instructions.

• Monitor soil pH – if too high or low, plants can’t properly absorb nutrients from fertilizer or soil.