Potassium, the “K” in the N-P-K, and always the third number.
The third in the three essential elements is the “K”, or Potassium, also known as Potash. Like phosphate, potash is a naturally occurring rock found in many parts of the world, mainly the Northern Hemisphere, with huge deposits in Canada and Russia. However potash is generally mined in traditional deep underground mines, and is an element that is widely used in agriculture in most parts of the world.
Potassium enables the plant to better utilize Nitrogen, as well as assisting in the synthesis of many plant processes. A further related benefit is a lawn grown with adequate levels of potassium will have superior tolerance to many turf diseases.
Some soils are naturally blessed with relatively high levels of potassium, but most are not, so as a rule of thumb it’s quite safe to apply potassium to all lawns. Unlike phosphorus a build up of potash should have no undesirable effects, such as leaching or run off. Indeed potash rock is actually a salt, and is liberally used in many “ice melt” products, and is a key component in ice melt sand mix used by our highways departments in northern climes.
Again, remember the balance…
Just like the first two numbers in the N-P-K , potassium is an important component when used in the right balance. Most lawn fertilizer manufacturers will have done their research on a variety of suitable N-P-K blends that will be adequate for most lawns.
A good rule of thumb is to apply a blend with a higher Nitrogen component early in the spring, as you’ll want the grass to “pop” and develop that healthy, lush dark green color.
As the summer develops an additional mix with a lower N component, but a higher P & K number will be beneficial for healthy root development to carry the pant through the drier summer months.
Closer to fall and the onset of winter, you’ll be looking for minimal “growth” but enhanced root development to properly winterize the plant. At this time you’ll be needing a very low N number, but much higher P & K.
The best way to apply your lawn fertilizer
Manufacturers take pains to blend all the components into a mixture of similar sized particles that are designed to be spread evenly over the lawn in some form of lawn fertilizer spreader. There are two distinct types of spreader, one that merely drops the fertilizer directly onto the lawn, and the other, far superior type is equipped with a “spinner”, a method of evenly applying the fertilizer over a wider swath, and where you can criss cross your paths at will, and the fertilizer will nicely blend over the entire, virtually eliminating any misses that you’re sure to get with the “drop” type.
An excellent lawn fertilizer spreader model is the Earthway 2150 Commercial 50-Pound Walk-Behind Broadcast Spreader, a robust and built to last spreader, that has a well designed spinning mechanism that will eliminate any misses.