15-0-15 Fertilizer: Benefits and When and How to Use It

15-0-15 fertilizer is great for feeding grasses, and sometimes for other plants that have too much phosphorus in the soil already.

fertilizer truck on pasture
fertilizer truck on pasture

Whether you’re a farmer, a gardener, or just a homeowner who likes to keep a sharp-looking property, knowing how to care for plants is essential.

And a big part of caring for plants is making sure they have enough to eat, along with other resources that they need to thrive.

If you want to give these resources to your plants, be they crops, grass or vegetables, you’ll need to fertilize the soil.

Sometimes this is easier said than done, and figuring out what fertilizer is best for your plants and your average conditions can be tricky.

But I am here to help you with a guide for using one of the most common special-use fertilizers, 15-0-15. I’ll tell you everything you need to know in the rest of this article…

What Does 15-0-15 Signify for Fertilizer?

When you see 15-0-15, or any other combination of numbers in a similar arrangement, you’re looking at a fertilizer ratio, expressed as percentages of elements.

The first number indicates the amount of nitrogen in the fertilizer, which is an essential nutrient for plants. The second number indicates the amount of phosphorus, while the third number represents the amount of potassium in the fertilizer.

This arrangement is usually abbreviated ‘NPK‘, after the atomic symbol for each element: N for nitrogen, P for phosphorus and K for potassium.

Knowing just this, it is a lot easier to figure out that 15-0-15 fertilizer has a lot of nitrogen and potassium but no phosphorous.

What Ingredients are Typically in 15-0-15 Fertilizer?

If you are buying 15-0-15, you know you will be getting fertilizer that contains nitrogen and potassium in the prescribed ratios, along with some trace elements.

The nitrogen and potassium are typically derived from sources like calcium nitrate, potassium sulfate, and urea.

Trace elements in 15-0-15 can come from natural sources such as kelp extract or manure, or they could be synthetically produced by chemical processes (depending on the maker and the product line).

Depending also on the brand and mix, your 15-0-15 might have added ingredients like micronutrients or soil conditioners to improve the efficacy of the fertilizer and help make it more balanced for different plants or soil types.

Benefits of 15-0-15 Fertilizer

The primary benefit of 15-0-15 is that it helps alleviate soil deficiencies in nitrogen and potassium while not adding any more phosphorous to the soil.

These two nutrients are important for photosynthesis, the process by which plants convert sunlight into energy, as well as the uptake of all other nutrients.

This makes it a special-use fertilizer for some folks: when phosphorous levels are too high, you definitely don’t want to add any more since it can stunt growth and damage to plants.

But they still need other nutrients all the same. That’s where 15-0-15 comes in…

Also, phosphorous-based fertilizer runoff can contaminate rivers and lakes, leading to oxygen depletion and algae growth that can harm plants, fish, and other aquatic life.

Phosphates also contribute to dead zones in the ocean where fish and other sea life cannot survive.

In addition, large-scale application of phosphate-based fertilizers can be difficult for farmers to manage over time since they accumulate easily in most soils.

Too much has numerous long-term consequences for the environment including soil degradation and reduced biodiversity.

Because of this, some areas entirely ban the use of fertilizers containing phosphorous, and that means you might not be allowed to use it at all! 15-0-15 is especially common in these areas.

What Plants is 15-0-15 Fertilizer Best For?

15-0-15 is ideal for any plant that needs plenty of nitrogen and potassium, but no phosphorous. This includes vegetables, grasses, trees, shrubs, some flowers, and many houseplants.

It’s also known to be great for some grasses that don’t need much phosphorous once established, such as Centipede, Bermuda, Zoysia, and St. Augustine.

How Do You Use 15-0-15 Fertilizer?

You’ll apply 15-0-15 the same way that you would any other fertilizer: with a sprayer, spreader or broadcaster depending on the type.

You can also use it as a soil amendment when planting seedlings or topdressing your lawn.

Before applying any fertilizer, however, always do a soil test to check the levels of nitrogen, phosphorous and potassium in your soil.

Then choose your fertilizer accordingly and adjust the amount of 15-0-15 so you don’t accidentally apply the wrong kind or too much…

When Should You Use 15-0-15 Fertilizer?

15-0-15 works fine as a regular fertilizer for any plants and soils that would typically benefit from it. It’s also used in response to climbing phosphorous levels, or when planting in any soil where nitrogen and potassium are low or missing, but phosphorous levels are high.

If you’are using it as a regular fertilizer for lawn care, spring is always a good bet to help your plants get ready for summer, and you can also apply it at the end of fall or early winter (in areas with mild or short winters) to help grass brace up for the cold.

For fast-growing summer grasses that thrive in high heat, you can also apply in the summertime.

When’s the Best Time To Apply 15-0-15?

Like pretty much all fertilizers, apply 15-0-15 when the soil is moist and temperatures are cool. This usually means early morning or late evening, when the sun isn’t at its peak.

With grassy areas, you should mow first; this will help ensure that the fertilizer gets down to the root zone without being wasted or broken up in subsequent mowings.

High temps and direct sun can easily lead to scorched foliage in conjunction with high levels of nitrogen!

How Much 15-0-15 Fertilizer Should You Use per Acre?

This is entirely dependent on the type and brand of your fertilizer. Some are more concentrated than others, so always refer to the manufacturer’s instructions for proper dosage.

As a general rule of thumb, however, plan on using about a pound for every 1,000 sqft., so for an acre of land that will come out to about 44-45 lbs. of 15-0-15 fertilizer (43,560 sqft. in an acre).

It’s also important to note that this number is just a general guideline, and you should always adjust the amount of fertilizer according to your soil test results! Too much can be damaging for your plants, so always use caution when it comes to fertilizing…

What’s the Best Method to Apply 15-0-15 Fertilizer?

It totally depends on the type: liquid, powder or granular. For liquid, you’ll need a sprayer that’s designed for fertilizer; there are several options available such as backpack, handheld and hose-end sprayers.

Powders need to be sprinkled and then watered in, while granular fertilizers can either be spread by hand or with a broadcaster.

Broadcast spreaders work great if your lot has large open areas with few obstacles, while hand-held spreaders are better for smaller spaces like an average lawn.

No matter which method you use, make sure to evenly distribute the fertilizer around your garden or lawn area to ensure that it’s being applied evenly and according to dosing instructions!

Is 15-0-15 Fertilizer Good for Lawns?

Yes, especially for nitrogen-hungry grasses or any grass that already has too much phosphorous in the soil. 15-0-15 is a great option because it helps balance out the nutrient levels.

Is 15-0-15 Fertilizer Good for Gardens?

It can be, but it is highly dependent on what you are growing and the overall soil status. Again, if phosphorous levels are high, then 15-0-15 can be an effective fertilizer to help balance out the overall nutrient levels in your soil.

It can be beneficial for plants that don’t need a “bump” of phosphorous to fruit or bloom.

What’s the Average Price of 15-0-15 Fertilizer?

15-0-15 will usually run anywhere from .18 to .22 cents an ounce, depending on location, brand, and where you buy.

Where Can You Buy 15-0-15 Fertilizer?

In most places, and especially those that have native grasses that will benefit from it. Hardware stores, garden centers, nurseries and even some feed stores carry 15-0-15 fertilizer.

You can also buy it online through big box retailers like Home Depot, Lowe’s, and Amazon.

What’s the Best 15-0-15 Fertilizer Brand?

There are a bunch of good ones, but I like Ferti-Lome Centipede Lawn Fertilizer. It’s reasonably priced and works like a charm.

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