When is 8-8-8 Fertilizer Best? | How to Use Triple 8 

When a “balanced” fertilizer is recommended to you, that could mean any number of NPK options, depending on soil conditions and the specific needs of your plants. But, when is it best to use lower nutrient percentages, such as in an 8-8-8 fertilizer? 

With just 8% each of nitrogen, phosphorus, and potassium, this NPK can be used for a wide variety of applications. Lawns, vegetables, evergreens, and ornamentals can all benefit from it. 

The sum of an 8-8-8 ratio can be achieved most accurately by simply purchasing a ready-made fertilizer labeled as such. Alternatively, you can organic materials such as well-aged compost that also contain valuable macronutrients.

When combined with elements like bone meal, cottonseed meal, and manure, a triple 8 NPK can be easily reached. Which will not only provide extra nutrients to your plants but increase soil fertility, as well.  

Understanding 8-8-8 Fertilizer Labels? 

With so many options to choose from, determining if a triple 8 fertilizer is the best one for you may seem a little discouraging. Especially 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. This reveals all the ingredients in that product starting with NPK content (macronutrients), then all secondary micronutrients, closely followed by trace elements and any included fillers. 

N-P-K Ratio 

So, what exactly is an NPK ratio? 

An NPK ratio is a three-numbered formula that indicates a fertilizer’s proportions of nitrogen, phosphorus, and potassium.

For example, an 16-16-16 fertilizer NPK has 16% nitrogen, 16% phosphorus and 16% potassium. Every plant requires these three elements in order to thrive. Just in different proportions or NPK ratios.

Each of these macronutrients plays a unique and vital role in plant cell formation, photosynthesis, and flower production. 


Nitrogen plays a key role in encouraging the growth of healthy, green foliage, by fueling the production of chlorophyll. Which ensures that photosynthesized energy is available for plants to create their own food. 

Nitrogen also fuels the proteins and enzymes responsible for regulating water and nutrient uptake and disbursement. 


Phosphorus is a major contributor to photosynthesis, focusing on flower and fruit production, rather than foliage. Triggering captured energy to convert starches and carbohydrates into food. 

At the cellular level, phosphorus contributes to the construction of those same proteins and enzymes that nitrogen uses to regulate water and nutrients. 


Potassium circulates water, nutrients, and photosynthesized food throughout your plants. It also triggers proteins and enzymes, formed by phosphorus to build healthy plant structures. 

Potassium increases disease resistance and protection against environmental stresses by managing moisture conservation. And is especially effective in encouraging large, well-formed fruit on vining crops. 

What is Triple 8 Fertilizer Used For? 

A triple 8 fertilizer’s intended use is to increase plant success, while not overwhelming them. This would also apply to houseplants. 

If you regularly add well-aged, nutrient-rich compost or manure to your topsoil, 8-8-8 fertilizer will help maintain a steady flow of nutrients to whatever is planted in it.  

A triple 8 NPK will encourage vibrant foliage for optimum photosynthesis on ornamentals and vegetables. While providing maximum support for flower and fruit formation. Although, many fruiting plants may need more phosphorus and potassium, once buds are set. 

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 promotes healthy growth. 

A balanced, 8-8-8 fertilizer can also offset the leaching of vital nutrients from the soil (in potted plants) that can otherwise be a consequence of frequent watering. An equal NPK will keep the growing medium fertile enough to keep them happy. 

8-8-8 vs 10-10-10 Fertilizer 

There’s only a 2% difference between a triple 10 and a triple 8 fertilizer. But, in small gardens, it’s important to note that a 10-10-10 fertilizer may actually be too high, especially in fertile soil. 2% can make all the difference between adequately supplementing nutrients and over-feeding. 

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, maybe higher in price. Caution is recommended, as liquid over-feeding is common and could lead to root 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 do carry a risk of root 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 eco-friendly. Since no watering is needed to activate and is less likely to contaminate nearby surface or groundwater. 

Fertilizer Spikes 

Spikes are really 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 8 Fertilizer 

A triple 8 fertilizer can be applied as a liquid or by working slow-release granules into the soil. 

When planting saplings in nutrient-weak soil, a handful of 8-8-8 granules, in the hole prior to planting, will help them establish more quickly and the gentle formula will diminish the risk of root burn.

Working granules into the top few inches of soil in borders, or applying a water-soluble option, will provide plants with a great start. 

With vegetables, applying a triple 8 NPK just after transplanting will contribute to an abundant harvest. When followed-up with an NPK higher in phosphorus and potassium, once buds set. 

Trees and Shrubs 

New, perennial trees and shrubs produce robust root systems, vibrant color and size faster with a triple 8 fertilizer in the 3rd and 4th month after planting. Once established, these typically don’t require any further fertilizing. If symptoms occur, a quality soil test should reveal any deficiencies. 

Citrus and Fruit Trees 

Citrus and fruit tree fertilizers typically contain more phosphorus and potassium to help with flower and bud production and disease resistance. While triple 8 may be fine for young saplings and feeding at the start of the growing season, it is best to switch to high potassium fertilizer or high phosphorus fertilizer as the season progresses. 

But, if you’re planting in poor soil, dry 8-8-8 fertilizer granules in the planting hole, in spring, will encourage faster establishment. 


Ornamentals need consistent nutrition to produce lots of summer color. A triple 8 NPK can ensure this and help accelerate maturity in annuals for a longer bloom time.

Infertile soil, a slightly watered-down dose of 8-8-8 fertilizer will better support healthy plants without the risk of overfeeding them. 

Vegetable Gardens 

Green, leafy veggies thrive when side-dressed with a triple 8 NPK. Tomatoes, squash, and melons, though, require more phosphorus and potassium once buds are set. 

If you’re starting with poor soil, a higher, balanced NPK after transplanting will create a healthy growing medium for the first couple of months. 

Is 8-8-8 Good for Tomatoes 

In poor soil, an 8-8-8 fertilizer will provide a healthy growing environment that will encourage a robust root system and vibrant foliage. After which, a 5-10-10 fertilizer would be more appropriate. 

If the use of a triple 8 NPK is continued, you’ll have more foliage than tomatoes. 


Houseplants require balanced nutrients for strong roots and healthy foliage. In rich potting soil, 8-8-8 fertilizer will support that without over-fertilizing. If your potting soil needs a boost, a 10-10-10 NPK would be more appropriate.

However, indoor bloomers like African violets, need more phosphorus to form flowers. These do well with a 7-9-5 NPK. 

Lawn and Grass 

Lawns and native grasses need phosphorus to grow thick and lush. Yet, relying on high nitrogen fertilizers to maintain a tough, vibrant structure. 

If a soil test has revealed nitrogen-rich soil beneath your grass, an 8-8-8 fertilizer would provide just enough nitrogen for a healthy lawn. 

8-8-8 Fertilizer FAQ’s