Meherrin 10-10-10-4S All Purpose Fertilizer

You've probably seen recommendations for using a 10-10-10 fertilizer on your plants because it's a reliable all-around choice for most uses. But what do those numbers actually mean? Here's a look at what that 10-10-10 fertilizer is actually delivering to your plants in terms of key nutrients, plus must-know tips on how and when to use this fertilizer for best results in your garden.

What Is 10-10-10 Fertilizer?

The three numbers on a fertilizer label indicate the amount of nitrogen (N), phosphorus (P), and potassium (K) in the bag. These are the three primary macronutrients needed for healthy plant growth.

The numbers separated by dashes are the percent by weight of each nutrient in the product. For 10-10-10 fertilizer, 10 percent of the product is a nitrogen source, 10 percent is a phosphorous source, and 10 percent is a potassium source. 

Multiplying the percentage by the weight of the bag or product tells you exactly how much of each nutrient you are buying. The guaranteed analysis label commonly lists the N-P-K components as total nitrogen, available phosphate, and soluble potash. 

For example, a five-pound bag of 10-10-10 fertilizer will have the following:

While 10-10-10 is a balanced or general-purpose fertilizer, its uses are no different from those of other fertilizers with the same ratio. A fertilizer with 4-4-4, 5-5-5, or 20-20-20 is the same ratio, just different concentrations. A product with an N-P-K rating of 20-20-20 is more highly concentrated (so you’ll use less per application) than a 10-10-10 or a 4-4-4.

When to Use 10-10-10 Fertilizer

Fertilizers with a 1:1:1 ratio, like 10-10-10, are called balanced fertilizers and are sometimes called general-purpose fertilizers. They are excellent for multiple uses, from feeding houseplants to boosting vegetable gardens. If you are only going to have one fertilizer sitting on the shelf, a 10-10-10 product is a good choice.

While we think of the first number, nitrogen, as feeding green, leafy growth and the second number, phosphorus, as encouraging blooms and rooting, plants need all three primary macronutrients for blooming, growing roots, and maintaining strong, vigorous growth. Thus, a balanced fertilizer will support all of these plant needs.

A 10-10-10 fertilizer is also a great choice for plants growing in containers. We don’t get soil tests on our potting mix, and the nutrients in a pot can quickly deplete. Choosing a balanced fertilizer takes some guesswork out of providing supplemental nutrition to your patio plants.

Best Practices for Using Fertilizer

While it seems like fertilizing plants is relatively straightforward, there are a few tips to remember for the best results.

1. Don’t Fertilize in the Fall

In areas that receive frost, plants harden their new growth and toughen up to prepare for freezing temperatures. New growth triggered by a late fertilizer application often doesn’t go through the hardening process and is more likely to be damaged by freezing temperatures.

2. Get a Soil Test

The soil in regular out-in-the-yard gardens can be a mystery. Fill dirt is often brought in during home construction and may be anything from good topsoil to sand and stones. Subdivisions are often built on old, exhausted agricultural fields. Even gardens in the country may yield a surprise. 

Arrange for a soil test and know what your garden needs before reaching for the fertilizer. Contact your state’s extension service to find out how and where to send a soil sample. The cost is nominal, and you could save yourself fertilizer and time.

3. Follow the Directions on the Label

No matter which product you choose, read and follow the directions on the label for application amount and frequency. Products specify a volume per area, like half a cup per 10 feet of row. You may see ½ pound per 100 square feet or, for liquid concentrate fertilizer, 2 tablespoons per gallon of water. Don’t give in to the temptation that more is better. Excess fertilizer can burn plants and cause water quality problems downstream.

4. Choose Slow-Release for Nitrogen

Of the three primary macronutrients—N, P, and K—nitrogen is most often deficient. Not only do plants use a lot of it, but it’s also more mobile in the soil than the other major nutrients. This means that nitrogen can easily move with the water in the soil profile, whether in a container or your garden, and be transported out of the root zone, a process known as leaching.

To help combat the leaching issue, many fertilizers coat some of the nitrogen product (and sometimes other nutrients) in a polymer, which takes a while to dissolve, creating a slow-release effect.