One of the most complicated parts of gardening is the process of making sure your soil has everything in it that your plants need to grow healthy and strong. You may have seen or heard the terms "macronutrients" and "micronutrients" before and wondered what exactly they meant. Does your soil need more of one or the other to thrive? The truth is that both macronutrients and micronutrients are essential to your plants' survival.

What Are Macronutrients and Micronutrients?

nitrogen, potassium, and phosphorus: three of the most important macronutrients for healthy soil

When you hear the terms macronutrients and micronutrients, they're not referring to the size or importance of a particular nutrient. In reality, they're used to indicate how much of each nutrient is needed by your garden. More specifically, macronutrients are needed in larger quantities than micronutrients, and they are often the first nutrients you think of when it comes to adding fertilizer to your soil. Micronutrients are needed in relatively smaller quantities but can be just as important to your plant’s health as their macronutrient counterparts.


There are two different classes of macronutrients: primary and secondary. The three "primary" nutrients are nitrogen, phosphorus, and potassium (probably the ones you that are the most familiar with when it comes to fertilizing). Each of these is needed in rather large quantities by your plants.

Secondary macronutrients include calcium, magnesium, and sulfur. They aren’t needed as much as the primary macronutrients, but they are still needed in more significant quantities than any micronutrient. Anyone that has ever dealt with blossom-end rot or a similar issue knows the importance of these elements.


Micronutrients are required in much smaller amounts. Typically, the plants you’re growing only need trace amounts of these nutrients to thrive. Micronutrients include iron, zinc, copper, manganese, molybdenum, chlorine, and boron. You may be surprised at some of these, but even things like iron and copper play important parts in the creation of healthy soil.

Testing Your Soil

Just as you know that too little calcium can result in blossom-end rot on your tomatoes and too much nitrogen can cause your peppers to produce a lot of leaves but only a few fruits and flowers, it’s essential to have the right levels of every essential nutrient in your soil. The problem is that it can be hard to know if something’s off in your soil until something actually goes wrong — unless you take the proactive step of testing your garden's soil, that is.

You can purchase a soil test at your favorite garden center or DIY store. Most of these will walk you through the steps of testing your soil for nutrients both macro and micro. It’s important to follow the steps carefully, as missing something could result in an inaccurate test result.

Have Your Soil Tested

a scientist conducting a soil test

Those that don’t feel comfortable testing their own soil may find it easier to have their soil tested by professionals. This often costs a little more than those DIY tests, but the results are far more likely to be accurate (especially if you've never tested your own soil before). There are laboratories all across the country that will analyze your soil to get a reading on which nutrients need to be added to it. On top of that, these tests can often provide more detailed information on your soil’s pH level, which can significantly impact your plants' nutrient uptake, and any soil problems that are common in your area. For instance, places with dry summers are prone to salty soil, which requires the addition of gypsum to be effectively counteracted.

Preparing Your Soil For Testing

you'll want to collect soil from several different areas in your garden to create a good testing sample

Most soil tests will have the same basic instructions in regards to preparing the soil for testing. You’ll start by taking a cup from the top four to six inches of soil and putting it in a bag. Do this again and again until you’ve got at least six samples from places all over your garden. You'll then mix all of the cups up and put two cups of this mixed soil into another plastic bag. This bag contains your actual testing sample.

With any luck, micronutrients and macronutrients will no longer be mysteries to you. At the very least, you now know that while your plants may need more of one nutrient than they do of another, they are all important for creating fertile soil and growing healthy plants. Soil testing and fertilizing are the best ways to keep your soil happy for years to come.