Deciphering NPK on Fertilizer Products

From Santa Fe Greenhouses E-Newsletter, April 20, 2006

By Cindy Bellinger

Gardeners everywhere are starting to plant, starting to fertilize. But help! When it comes to fertilizer, what do you use? The group of hyphenated numbers on bags, bottles and jars of fertilizer can be baffling. What's more, those numbers are often accompanied by the letters NPK. What do they mean?

Figuring this out doesn't have to be difficult. The numbers and the letters refer to the three basic nutrients needed for healthy plants.

N = nitrogen

P = phosphorus

K = potassium (usually listed as potash).

Our buyer for Santa Fe Greenhouses, Andy Mogg, explains it like this: "The first number is for green, the second number is for roots and bloom. The third number is for the structure of a plant like cell walls; it strengthens and reinforces," he said.

Numbers are written like 2-1-1 or 3-12-12 or any other combination. They indicate the ratio of nitrogen, phosphorus and potassium in the formula.

Depending on the time of year, you'll want different fertilizers; consequently, you’ll want different numbers. In the spring plants need more nitrogen so look for higher first numbers. Some fertilizers list 0 as the first number. For spring growth, don’t use that one.

What gardeners need to strive for is a balance of top and bottom growth.

We recommend using a balanced fertilizer and a good one is Yum Yum Mix. It has a 2-1-1 ratio. Another good one is Gro-Power with a 5-3-1 ratio.

Another consideration is whether you want to use a chemical or organic fertilizer. In the short term, they’ll do the same work. In the long haul the chemical fertilizers deplete the soil and make the plants dependent on more and more applications. An organic fertilizer adds to the soil, which increases the nutrients.

"It’s all about balance," said Mogg, "and the kind of health you want your garden plants to achieve."

Cindy Bellinger

Editor