N-P-K info for a newbie?

[GreenPinky]

I’ve recently started to address some problems in my lawn and kept seeing 3 numbers on many products. I’ve come to learn these to stand for how much N, P & K are in the product. But would someone help break this down for a newbie please? What time of year is N more important or P or K? And do the numbers matter or is it the ratio? Is 10-6-4 the same as 5-3-2, or if I apply 5-3-2 at twice the rate would that equal 10-6-4? Sometimes I see Very small numbers like 0-4-2 and other times I see large numbers like 60-2-0. What’s the significance of these numbers. And again, what time of year should I be focusing on applying these different fertilizers to the lawn?

 

[oneeye]

N P K, is nitrogen , phosphorus potassium. Grass uses Nitrogen the most and if you have clay soil you will need a high # of nitrogen. A fertilizer I used in landscaping is 21-0-0 for clay soils. If the soil is acidic, I would use a fertilizer with more P and K in it like, 21-7-14. Nitrogen greens up your lawn and helps it grow.
Phosphorous stimulates root growth and helps seeds sprout.
Potassium helps grass withstand stresses like disease and drought.
The small numbers on bags of fertilizers are often organic fertilizers. and large numbers are synthetic and using more is not always better. The best time to apply fertilizer is when the summer or warm season grass is actively growing. If you apply it too early you will feed the weeds and that's why I wait until the temps reach upper 80s to 90s before I added it to my lawns. If you mix two different fertilizers together you will knock the CEC "Cation Exchange Capacity" off and burn the heck out of your grass and even poison your soil. .

 

[GreenPinky]

N P K, is nitrogen , phosphorus potassium. Grass uses Nitrogen the most and if you have clay soil you will need a high # of nitrogen. A fertilizer I used in landscaping is 21-0-0 for clay soils. If the soil is acidic, I would use a fertilizer with more P and K in it like, 21-7-14. Nitrogen greens up your lawn and helps it grow.
Phosphorous stimulates root growth and helps seeds sprout.
Potassium helps grass withstand stresses like disease and drought.
The small numbers on bags of fertilizers are often organic fertilizers. and large numbers are synthetic and using more is not always better. The best time to apply fertilizer is when the summer or warm season grass is actively growing. If you apply it too early you will feed the weeds and that's why I wait until the temps reach upper 80s to 90s before I added it to my lawns. If you mix two different fertilizers together you will knock the CEC "Cation Exchange Capacity" off and burn the heck out of your grass and even poison your soil. .

That’s very helpful thank you. And so for an established lawn, if I wanted to fertilize cool weather grass this time of year, nitrogen would likely be the most important component or at least the one which should be the highest number?

 

[oneeye]

Yes for grass, Nitrogen is the most important # for your lawn. When I did lawns for a living, I always got a soil test in late Winter to know what and how much to apply to each lawn and each test lasted 5 years. Then I tested the soil after every 5 years. That way I learned what nutrients to add, and what the pH and the CEC of the soil would be for each lawn. On most of the clay soils I only added nitrogen 21-0-0 to the lawns 2 times a year. May and in the end of Sept were the times I used it while it was warm. I paid $30 us dollars for each test and they paid for themselves in the first year.