What does Complete Fertilizer mean?A complete fertilizer is a fertilizer blend or mix that contains the three main plant nutrients: nitrogen (N), phosphorus (P), and potassium (K), in the forms of potash, phosphoric acid, and nitrogen.
On a complete fertilizer label, the ratios of these primary plant nutrients are revealed as the product's N-P-K ratio. For example, a fertilizer with equal amounts of each element would have an N-P-K of 5-5-5. This would be considered a general-purpose, complete fertilizer. However, to be considered complete, a complete fertilizer doesn't need to have equal amounts of each of these, just close to it.
Complete fertilizers can be store bought, or a gardener can mix their own complete fertilizer up by mixing individuals components together, customizing their ratios of each nutrient.
Potassium has been known to help the fruiting and flowering process while contributing to the overall health by boosting the plant’s immune system. Nitrogen, on the other hand, ensures that the leaves remain in pristine health, and phosphorus encourages a healthy and steady root growth.
In some cases, compost can be considered a complete fertilizer, depending on what is added on the compost heap. Compost normally consists of a mixture of dry and wet ingredients and some wet ingredients have been known to release nitrogen. For example, table scraps, yard waste, and coffee grounds all contribute to the compost heap’s nitrogen content. In fact, leaves and coffee grounds have also been known to enhance the heap’s phosphorus and potassium content.
According to gardeners, manure can also be considered a complete fertilizer, provided that the animal was fed a nutrient-rich and healthy diet. For complete fertilizer, however, it’s best to mix different types of manure since they each feature different levels of nutrients.
A fertilizer that only supplies one or two of the three main plant nutrients is an incomplete fertilizer. These products are cheaper and would be ideal to use on soils that are, for example, already rich in one nutrient or another.
Source: Maximum Yield,"Complete Fertilizer",https://www.maximumyield.com/definition/26/complete-fertilizer