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? 

Getting to grips with reading and understanding fertilizer labels can feel like a tall order when there are so many products to choose from. But, once you know the basics, selecting the right product for your garden is easy.

On the back of the container will be an ingredients list. This reveals everything that has been used to create the product and you can expect to see minerals such as copper, zinc, calcium, iron, magnesium, boron, and manganese included.

In addition, you’re likely to see nitrogen, phosphorous, and potassium also on the list. These three elements are macronutrients and are referred to in the fertilizer world as the NPK ratio.

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N-P-K Ratio 

So, what exactly is an NPK ratio? 

An NPK ratio is a three-numbered formula that indicates the percentage ratio of nitrogen, phosphorus, and potassium contained within the fertilizer product. So, for example, a 16-16-16 fertilizer NPK has 16% nitrogen, 16% phosphorus, and 16% potassium.

These three macronutrients are vital to plant formation, growth, and health and without them, plants would not be able to grow or survive. Some plants need an even amount or ‘balanced’ NPK ratio and other plants need more of one and less of another.

Here’s a breakdown of what each of the primary macronutrients does:


  • Encourages the growth of healthy, green foliage, by fueling the production of chlorophyll
  • Makes photosynthesized energy available so that plants can create food from starches and carbohydrates 
  • Provides energy for the proteins and enzymes that regulate water and absorption of nutrients


  • Supports flower and fruit production
  • Enables captured photosynthesized energy to convert starches and carbohydrates into food 
  • Contributes to the construction of proteins and enzymes


  • Facilitates water, nutrients, and food absorption and distribution throughout plants
  • Triggers the energy required to build proteins and enzymes
  • Ensures plants build resilience to disease and protection against extreme hot and cold temperatures
  • Helps plants to conserve moisture
  • Supports the growth of larger and more plentiful flowers and fruits 

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 contribute to soil and water source contamination. 

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 need to be mixed into the soil around plants or applied before planting. Alternatively, they can be dissolved in water and used as a fertilizer ‘tea’. 

A value for money option as they tend to come in larger quantities and have a great shelf life provided they are stored safely and kept dry.

Similar to fast-acting liquids, they are prone to causing root burn. This can happen if they are used too often, in high concentration, or if splashed on tender leaves. I recommend following the specific manufacturer’s instructions to avoid this. 

Slow-Release Granules 

Concentrated granules can provide nourishment over an extended period of time rather than all at once. Results tend to be noticeable within a few 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