19-19-19 Fertilizer: How to Use It in the Garden and Lawn

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A gardener applying fertilizer to a plant.

If you’ve ever tackled a garden or picked up a houseplant for your windowsill, you’ve encountered fertilizers. One of the most common ones is known as Triple 19, or 19-19-19 fertilizer. But just what do these numbers mean, and what’s in Triple 19 fertilizer that makes plants grow?

19-19-19 fertilizer contains of 19% nitrogen, 19% phosphorous and 19% potassium. Nitrogen, phosphorus and potassium are key nutrients plants need for healthy growth, and Triple 19 is often called a “balanced” fertilizer because it contains all three nutrients in equal amounts. Triple 19 is a multi-purpose fertilizer that works well for many uses, including fruit-bearing trees, vegetable gardens and landscape plantings.

Let’s jump into a quick rundown of what is in Triple 19 fertilizer and how to use this knowledge to help your plants grow bigger and better.

What is 19-19-19 Fertilizer?

Let’s talk about what the numbers mean. Ratios are important for comparing fertilizers since they indicate the concentration of primary nutrients in a given formula.

This ratio is known as the fertilizer analysis or the NPK number.

These numbers stand for the respective amount of nitrogen (N), phosphorus (P), and potassium (K) the fertilizer contains. These three elements are the most important macronutrients required for plants to grow:

Graphic showing what nitrogen, phosphorus and potassium do for plant health.

The NPK number of any given fertilizer tells you the percentage by weight (ratio) of these three macronutrients in each bag of fertilizer.

So, a bag of NPK 19 19 19 contains 19% each of nitrogen, phosphorus, and potassium, for a total of 57% active ingredients. (The remaining 43% of inactive ingredients are fillers meant to carry the nutrients or other substances meant to make the fertilizer easier to dissolve, reduce or increase soil pH, etc.)

Here’s what that actually means in practical application:

  • A 100-pound bag of 19-19-19 fertilizer contains 19 pounds each of nitrogen, phosphorus and potassium.
  • A 50-pound bag of 19-19-19 fertilizer contains 9.5 pounds each of nitrogen, phosphorus and potassium.
  • A 20-pound bag of 19-19-19 fertilizer contains 3.8 pounds each of nitrogen, phosphorus and potassium.

Since Triple 19 provides equal parts of nitrogen, phosphorus and potassium, it has a 1-1-1 ratio and is a balanced formula. This means that 19-19-19 fertilizer provides ideal nutrition for many types of plants, much the same way that you aim to eat balanced meals that supply a variety of nutrients.

Triple 19 isn’t the only balanced fertilizer out there. 10-10-10 (Triple 10) or 12-12-12 (Triple 12) also have a 1-1-1 ratio. So they provide balanced nutrition and are ideal for multiple uses, like 19-19-19. However, formulas like 10-10-10 and 12-12-12 contain a lower concentration of nutrients than 19-19-19.

Benefits of 19-19-19 Fertilizer

Of all the many (many!!) options out there, what’s so great about 19-19-19 fertilizer?

There are a few strong reasons to choose Triple 19:

Cost Per Pound

At any garden supply store, you’ll be able to find similarly sized and priced bags of Triple 10 and Triple 19 fertilizer.

But a bag of 19-19-19 contains nearly double the amount of nutrients per pound than 10-10-10, so your cost per pound of nutrients is basically halved. If you’re worried that 19-19-19 is too high of a dose for your plant, you can simply apply it at half the rate recommended on the bag.

By doing this, a bag of Triple 19 can go twice as far as a bag of Triple 10 for the same price. Or you can get your job done with a single bag of 19-19-19 whereas you may need two bags of 10-10-10.

All-Purpose Use

Instead of being a targeted formula that only works for certain plants, 19-19-19 fertilizer is a workhorse that’s effective for many uses in your home landscape.

It works best for trees, shrubs, vegetable gardens and houseplants. In a pinch, it will also serve to fertilize lawns.

Jumpstart Soil

If you garden in the same plot of ground every year (and most people do just that), the soil’s stores of primary nutrients can get depleted over time.

If you have a few plants in your garden that are languishing, a shot of 19-19-19 will help perk them up. With its high NPK ratio, Triple 19 can quickly help make up for many nutrient shortfalls in the soil.

However, if you’re especially low on certain nutrients as indicated on a soil test, you’ll need a more targeted formula to address the problem. We’ll talk more about this point a little later on.

Is Triple 19 Good for Lawns?

This is one of the most common questions asked about 19-19-19 fertilizer, and we asked Ray Brosnan, a landscape professional with over 20 years of experience, for his thoughts on Triple 19 for lawns.

“Lawn fertilizer requires much more phosphorous to start with, transitioning into needing more nitrogen when the lawn matures. Triple 19 Is not really any good as it doesn’t deliver the right amount of balanced nutrients to the soil.”

For new grass, consider a product like The Andersons Premium New Lawn Starter formula (NPK 20-27-5), which has a high ratio of phosphorous to get those new roots started off strong.

Once you get past the initial planting/establishment phase, Milorganite’s EasyGo (NPK 6-4-0) is a good option. One nice thing about it is the slow-release formula enriches your lawn over time, so there’s no dangerous nitrogen toxicity. Also, Milorganite added iron for healthy root development.

But there’s good news here, too. Ray also shares that applying 19-19-19 fertilizer “won’t actively harm your lawn so if you’ve got some laying around don’t be afraid to throw some down.” Good to know!

Where To Use 19-19-19 Fertilizer

We mentioned that Triple 19 has great all-purpose applications, but it’s still important to be conscious about what plants and how often you’re using it to get the best effects.

The best places to put a 19-19-19 formula to work are these:

  1. Fruit trees
  2. Established decorative trees and shrubs
  3. Vegetable gardens
  4. Houseplants
  5. Large-scale farming

1. Fruit Trees

According to Jen Stark, founder of the home and garden website Happy DIY Home, Triple 19 is a great choice for trees that produce edible harvests.

Jen says, “The reason behind this is that it has higher phosphorus levels on it that can help fruit trees like peaches and apples to produce blossoms and fruit.”

Also, the high concentration of nitrogen and potassium helps your trees produce healthy foliage and a strong root system.

So if you want a maximum yield from your fruit trees this year, 19-19-19 fertilizer can help you get there.

2. Established Decorative Trees and Shrubs

As is the case with fruit trees, the high NPK ratio in 19-19-19 fertilizer supplies blooming or foliage trees and shrubs with the nourishment they need for healthy roots and foliage.

Use this fertilizer on already-established trees and shrubs of all kinds–flowering, deciduous, or evergreen.

It takes at least 3 years after planting for your new tree to develop the beginnings of a strong root system and fully acclimate to its new home. At this point, 19-19-19 fertilizer is a great choice that provides all the balanced nutrition that a slightly older tree needs.

3. Vegetable Gardens

Triple 19 is also an effective fertilizer for vegetable gardens because it contains high amounts of all three macronutrients.

When you want to fertilize your entire garden with a single product, NPK 19-19-19 is a convenient choice that produces good results. The balance of all three key nutrients is especially well-suited to leafy crops, like spinach, kale and lettuce.

While 19-19-19 will give a nice nutrient boost to tomatoes and peppers, some gardeners feel they get the very best results when they use a targeted fertilizer for fruiting crops. Dr. Earth Home Grown (NPK 4-6-3) is a popular choice that has just a bit more phosphorus to help produce blossoms and fruit. I love this formula, personally!

4. Houseplants

Houseplants respond really well to balanced fertilizers like 19-19-19. However, you probably won’t need to apply it at full strength; diluting it down by 50% or even 75% is about right for most houseplants.

NOTE: All container plants should be in pots that have good drainage, but it’s especially important for houseplants that you’ll be fertilizing. If it can’t drain out, the fertilizer will start to build up within the soil to high levels that actually damage root tissue and plant growth. 

RELATED: We love houseplants around here! Visit our posts on Silver Bay Aglaonema, Philodendron Micans and Scindapsus Pictus to see just a few!

5. Large-Scale Farming

One of the most common applications of 19-19-19 fertilizer is large agricultural operations that specialize in hay, clover, and soy.

The high NPK levels help support foliage and stem development for hay and clover, and the phosphorus element is helpful produce plentiful soybeans.

Some ranchers will also use it to help grow pasture grass for grazing land. If you’re involved in animal husbandry, it may help your pastures be more productive.

Where to Avoid Using 19-19-19 Fertilizer

With its equally high levels of all three key macronutrients, 19-19-19 is not always the best fertilizer for every garden.

That’s because of the different functions that each of the three primary nutrients fulfills for plants. It’s similar to how a child’s multivitamins have a different composition from an adult’s– nutrient needs change at different stages of growth.

There are some instances where you’re better off with a more targeted formula than what 19-19-19 can provide:

  1. Severely nutrient-deficient soil
  2. Newly-planted landscapes
  3. Bloom-heavy plants

1. Severely Nutrient-Deficient Soil

If you are turning a new plot of ground into a garden, 19-19-19 may be a fine choice–but you don’t want to assume that it is!

Instead, do a soil test first. A test will analyze the nutrient profile for your soil from a sample you provide. It may already be high in nitrogen, or perhaps it has plenty of nitrogen and potassium but is very low in phosphorus. Then you can choose fertilizers with the right nutrient analysis.

You can get your soil tested through your local extension office. These tests are often comprehensive, showing information like basic nutrient levels and pH as well as advanced tests on heavy metals and other data.

If you’re not sure how to contact your extension office, look up your county’s contact information with this tool from the National Pesticide Information Center.

However, the timeframe for getting your results may vary. And the tests can get quite expensive, especially if all you need is to find out your NPK levels.

One of the easiest and most affordable ways to get a soil test is through SoilKit.com. For basic tests (which is what most home gardeners need), this is a fantastic option.

You order a test kit from them, collect your sample and send it to SoilKit using a pre-paid mailer. You’ll get your results within 48 hours of SoilKit receiving your sample.

They test for key factors of soil health, including these:

  • Soil pH
  • NPK
  • Manganese
  • Calcium
  • Iron
  • Boron
  • Zinc
  • Water-retention capability

Once you get your test results, you’ll know if NPK 19 19 19 is a good fit or if you need to use a more specialized fertilizer to replenish certain nutrients.

SoilKit testing

2. Newly-Planted Landscapes

When trees and shrubs are young, 19-19-19 is not the best fertilizer for them. New landscapes will do better with fertilizers that have a higher percentage of phosphorous and potassium and lower nitrogen.

Phosphorus helps plants develop strong root systems, and potassium aids in photosynthesis and cellular regeneration, both of which are key for getting your new grass off to a good start. On the other hand, nitrogen helps plants develop a deep green color and dense leaf growth, so it’s better for established plants.

A product that’s specifically designed for new plantings is a better option here. For new trees and shrubs, Fertilome’s Root Stimulator and Plant Starter Solution (NPK 4-10-3) is a good choice that contains hormones that encourage root development.

If Triple 19 is all you have available for your newly-planted trees or shrubs, make sure to use less than half of the recommended dosage to avoid giving too much nitrogen.

3. Bloom-Heavy Plants

Phosphorus is the key nutrient for plants to produce big, healthy, eye-catching blossoms.

Roses, begonias, petunias, dahlias- If you want your flowering plants to put on a show, skip the Triple 19 and give them a bloom-boosting fertilizer with extra phosphorus instead! This organic formula from Dr. Earth (NPK 3-9-4) is a great option.

Where to Buy 19-19-19 Fertilizer

You’ll find 19-19-19 fertilizer comes in liquid and granular form.

  • Liquid types are better for houseplants and for foliar (leaf-spraying) application of landscape plants.
  • Granular types are great for all landscape plants, vegetable gardens, and trees since they are mixed into the top few inches of soil and then dissolve over time as the plants are watered.

Organic Triple 19 can be difficult to find, at least online. But it may be available in your local nursery or garden store. You could also try using a lower-dose balanced organic fertilizer and applying it at a double amount.

You can buy conventional 19-19-19 fertilizer in brick-and-mortar stores like Lowe’s and Home Depot.  You can also order it online from these retailers, as well as on Amazon. A couple great Amazon-available options are:

How to Use 19-19-19 Fertilizer

Early spring, just after you’ve passed your last regional frost date, is the best time to apply Triple 19 fertilizer for the new growing season. If you’d like, you can also apply it in the fall.

We’ll mention it again: It’s always a good idea to test your soil profile before applying fertilizer.

If 19-19-19 turns out to be the right choice for you, consult the instructions on the package to find out the dosage. This is usually based on the size of the trunk of the tree or shrub in question, or the square footage of a garden bed.

Follow the directions closely, being careful to never over-apply fertilizer. It’s too much of a good thing and can lead to severe cellular damage in your plants.

For fertilizing individual trees/shrubs or your veggie garden, deposit the correct amount of fertilizer at the base of the plant near the drip line. Use your hand or a hand rake to work the granules into the soil. A handheld shaker spreader is a great tool to use here.

If using it as a liquid foliar spray, mix water and fertilizer in the amounts given in the manufacturer’s instructions. Use a backpack sprayer (for big jobs) or a handheld sprayer (for small ones), and apply directly onto the foliage until the leaves are dripping wet. 

Make sure to do this on a cool day or early in the morning to avoid scorching the leaves in harsh sunlight.

This video from MIGardener does a great job of outlining the foliar feeding process:

To broadcast Triple 19 over a large area, use a wheeled or handheld broadcast spreader loaded with the recommended amount of fertilizer for your square footage. You can adjust the gate of the spreader to deposit the right amount of fertilizer as you walk–not too much and not too little.

Take note of how often the instructions tell you to reapply. This can be anywhere from 4-6 weeks. Count forward on your calendar and make a note to yourself to fertilize again at the right time.

Frequently Asked Questions about 19-19-19 Fertilizer

Both formulas have a 1-1-1 ratio, meaning that they contain equal amounts of nitrogen, phosphorus and potassium. But 20-20-20 has these nutrients in slightly higher concentrations. Whereas Triple 19 would have 19 pounds of each nutrient in a 100-lb bag, Triple 20 would have 20 pounds of each.

When it comes down to performance differences between the two formulas, the results will be about the same.

Morning is best in the summertime, but during spring and fall when temps are cooler, you can fertilize almost any time of day.

Key Takeaways

  • Triple 19 fertilizer contains nitrogen, phosphorus and potassium at 19% of total weight each. For a 100-pound bag, there would be 19 pounds each of these three nutrients.
  • Nitrogen is essential for healthy foliage with deep green color, phosphorus encourages root development and blossom/fruit production, and potassium aids in cellular health and disease-resistance.
  • 19-19-19 fertilizer is a great choice for fruit trees, decorative trees and shrubs, vegetable gardens and large-scale agricultural uses. The high percentage of nitrogen, phosphorus and potassium all contribute to healthy foliage, roots and harvest production.
  • Triple 19 isn’t the best choice for lawns since its balanced formula doesn’t supply the higher concentrations of certain macronutrients that grass needs in different stages of life. However, it also won’t harm established grass if you apply it.

Final Thoughts

Hopefully, this article demystified the ratio and macronutrients behind 19-19-19 and helped you decide if this is a good option for your needs. Remember: soil tests are your friend, and never over-apply fertilizer!

Do you still have questions? Drop them in the comments below, and we’ll answer!

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