K Is for the K in N-P-K Blended Fertilizer

This time of year, home improvement stores, garden centers and even mini-marts have bags of fertilizer on sale for the enthusiastic gardeners out there. Fertilizers come in many variations and it is important to buy the right kind for the plant you are fertilizing. The blend you use on your grass is not the same kind you use for your fruit and ornamental trees.




Bags of fertilizers are labeled with a series of numbers, usually 3, in a pattern like 10-10-10 or 12-12-12. Those numbers represent the percentages of specific components of the fertilizer. In order they stand for nitrogen (N), phosphorous (P) and potassium (K). These three nutrients are the keys to most plant growth. They each have a job to do. Let’s look at potassium.



Potassium, also known as potash, is the K in the NPK formula. The k comes from its Latin name kalium. Potassium is important to flower and fruit development. It assists in the building of starches and sugars and contributes to plant growth and disease resistance. It is naturally found in wood ash which is where the potash name comes from.



You can tell if there is a shortage of potassium because leaves will scorch more easily, fruit crops will be low and plants will be more prone to disease. A soil test can confirm the shortage.



Potassium can be applied to trees as part of a blended fertilizer or separately in liquid form. It typically lasts two to three years in the soil unless you have a crop of heavy fruit production. If you need to add blended fertilizer, look for one with a higher K designation.