When to Use 19-19-19 Fertilizer? | How to Use Triple 19

When starting a new garden border, vegetable bed, or laying new sod, your soil is going to need to be as fertile as possible. Not only for all those new plantings to survive, but also to thrive.

If you amend your soil with well-aged compost, manure, and other organic compounds to increase its fertility, prior to planting, that’s great!

If not, that’s perfectly ok too but you are likely going to need to give plants a helping hand with a balanced fertilizer and one that provides a high concentration of N-P-K.

The nutrient ratio in a 19-19-19 fertilizer is pretty simple. 19% nitrogen, 19% phosphorus and 19% potassium. Which is near twice as much of each as in a standard 10-10-10 fertilizer. Making it the perfect choice to revitalize tired and infertile soil.

Then, once a soil test confirms that your soil is up to par, a 19-19-19 fertilizer can easily be diluted down to a 10-10-10 for continued use on lawns, garden beds, and vegetables. Not to mention, houseplants. 

Understanding 19-19-19 Fertilizer Label? 

With so many NPK fertilizer options to choose from, deciding on the best one may seem tedious. When all you want to do is to grow healthy plants.

No worries! You can easily match a fertilizer to your plant goals by understanding the fertilizer labels. 

Most fertilizers state their NPK ratio right on the label. On the back of the container should be an ingredients list. Which reveals all the ingredients in that product.

NPK content (macronutrients), then all secondary micronutrients. Followed by trace elements and any included fillers. But, what exactly is an NPK ratio? 

N-P-K Ratio 

Every fertilizer label reflects three numbers, separated by dashes. This is its N-P-K ratio, indicating the fertilizer’s proportions of nitrogen, phosphorus, and potassium.

For example, an 19-19-19 fertilizer NPK has 19% nitrogen, 19% phosphorus and 19% potassium. Every plant requires these three elements in order to thrive. Just in different proportions or NPK ratios.

Each of these macronutrients plays a vital role in cell formation, photosynthesis, nutrient distribution, and flower and fruit production. 


Nitrogen plays a vital role in encouraging the growth of healthy foliage, by fueling the production of chlorophyll. This gives foliage its green color and ensures that photosynthesized energy is available to convert starches and carbohydrates into food. 

This multi-tasking macronutrient also fuels the proteins and enzymes that regulate water and nutrient uptake and disbursement. High nitrogen fertilizer is typically formulated for lawns and other plants where foliage is the primary focus.


Phosphorus is key in the process of photosynthesis. Once the chlorophyll is produced, this macronutrient triggers the energy captured by the chlorophyll to convert starches and carbohydrates into food. Another important (and more visible) function of phosphorus is the creation of abundant flowers and fruit, rather than foliage. 

Phosphorus begins its work at the cellular level. Contributing to the construction of those same proteins and enzymes that nitrogen uses to regulate water and nutrients.


Potassium is responsible for the circulation of water, nutrients, and photosynthesized food throughout your plants. It also activates those proteins and enzymes that were formed using phosphorus and nitrogen to build a healthy plant structure. 

High potassium fertilizers contribute to a plant’s resistance against disease and extreme heat and drought by helping them to conserve moisture. And is especially effective in encouraging large, well-formed fruit on vining crops like tomatoes, squash, and melons.

What is Triple 19 Fertilizer Used For? 

The intended use of a triple 19 fertilizer is to increase plant success and fertility in poor soil. But it’s also effective for use on plants grown in hanging baskets to accommodate for the heavy leaching that occurs.  

When used appropriately, a 19-19-19 NPK encourages vibrant foliage for optimum photosynthesis. While providing maximum support for flower and fruit formation.

For in-ground plantings, a 19-19-19 NPK should only be used at full strength for a short time. Followed by either a diluted version or a feed with a lower NPK such as 8-8-8 fertilizer – whatever is better suited to the needs of specific plants. 

Being aware of the potency of such equally high NPK amounts will help you to determine what to use this on and how much.

Why Use a Balanced Fertilizer? 

Indoor and outdoor plants will often require more of one macronutrient than another and at different times. When planted in poor soil, a balanced fertilizer can provide even nutrient availability that then promotes healthy growth. 

A balanced, 19-19-19 fertilizer can also offset the leaching of vital nutrients from the soil (in potted plants) due to frequent watering. An equal NPK will keep the growing medium fertile enough to keep them happy. 

Fertilizer Type 

There are four different application methods available to make nourishing your plants and soil easier. 

  • Quick Release – liquid or water-soluble options provide immediate nutrient delivery. Offering accelerated, visible improvement for plants growing in poor soil.
  • Slow-Release – granules and spikes offer a steady stream of nutrients over an extended period of time, with fewer applications.
  • Organic – made from natural materials like well-rotted plant material and animal bi-products that, when combined, meet the NPK needs of most plants. 
  • Inorganic – manufactured with synthetic chemicals. These can result in a higher yield, but can also potentially contaminate soil and nearby water sources. 

Liquid Concentrate 

Concentrates, when mixed with water, help keep soil pH balanced and are often formulated as foliar sprays to combat deficiencies in leaves. 

Premixed options are available, as well but, these may be higher in price. Caution is recommended, as liquid over-feeding is common and could lead to root or leaf burn. 

Water Soluble Powder 

Powder fertilizers can be applied directly to the soil around plants or diluted in water as a “tea”. 

Powders are also some of the most economical and have a virtually indefinite shelf life. But they too carry a risk of root or leaf burn if manufacturer instructions aren’t followed. 

Slow-Release Granules 

Concentrated granules can provide consistent nourishment for up to nine months, with results showing in just a couple of weeks.

They’re less likely to cause root burn and are considered more eco-friendly. Since they are less likely to contaminate nearby surfaces or groundwater due to run-off. 

Fertilizer Spikes 

Spikes are convenient to use, especially if you have a substantial container garden. Pre-measured in various sizes, they’re easy to push into loamy soil.

Nutrients are slowly released by microorganisms in the soil and carry the added benefit of stimulating an increased resistance to disease and pests. 

How and When to Use Triple 19 Fertilizer 

A 19-19-19 fertilizer can be applied as a liquid when watering or by spreading slow-release granules. In container gardens, fertilizer spikes can be very effective. 

When planting new saplings in poor soil, a handful of triple 19 granules, in the hole prior to planting, will encourage the faster establishment and new growth. 

In borders, working granules into the top few inches of soil or applying a water-soluble option, just after planting, will provide plants with a great start. 

With vegetables, applying a triple 19 just after transplanting will promote an abundant harvest. 

Trees and Shrubs 

Using a fertilizer for trees and shrubs, even in poor soil, will help to produce robust root systems, vibrant color, and size faster. 

Use a triple 19 fertilizer in the 3rd and 4th months after planting. Once established, these typically don’t require any further fertilizing. If symptoms occur, a soil test can reveal any deficiencies. 

Fruit Trees 

Fruit tree fertilizers tend to contain more of one macronutrient than another. So a triple 19 may not be suitable for them, in the long term.

But, if you’re planting in poor soil, a handful of dry 19-19-19 granules into the planting hole, in spring, will also help these get established quickly. 


Ornamentals need consistent nutrition to produce lots of summer color. In less-than-fertile soil, a triple 19 NPK can ensure this and help accelerate plant maturity. 

If you already benefit from rich, fertile soil, select a feed with a lower N-P-K rating such as a Triple 10 fertilizer, or better still, select a high phosphorous fertilizer to encourage better blooms, as well as healthy stems, leaves, and roots. 

Vegetable Gardens 

Fertilizers for tomatoes, squash, and melons contain more phosphorus and potassium than nitrogen and should be used once buds are set. Green, leafy veggies, on the other hand, thrive when side-dressed with a much lower NPK.

But, if you’re stuck with poor soil, it’s beneficial to start with a 19-19-19 NPK, for a few months, just after transplanting. 


A 19-19-19 fertilizer is typically too high for houseplants. It would need to be significantly watered down. A triple 8 NPK (or a 10-10-10 for nutrient-deficient soil) will support their needs without over-fertilizing.

Bloomers like bromeliads, need more phosphorus to form flowers and do well with a 7-9-5 NPK. 

Lawn and Grass 

Feed for lawns and native grasses need phosphorus to grow thick and lush. Yet, they also need a high nitrogen fertilizer to maintain a tough, vibrant structure. 

If a soil test has revealed nutrient-poor soil beneath your grass, a 19-19-19 NPK would infuse your soil with enough nutrients to support a healthy lawn.  

19-19-19 Fertilizer for Garden FAQ’s