, Gloucester, MA

July 5, 2013

Here's the dirt to decipher fertilizer facts

North Shore Gardener
Barbara Barger

---- — Q: What do all the numbers and letters on fertilizer packages mean? Do they think that you have a degree in chemistry?

A: You don’t have to have a degree in chemistry to read the fertilizer label. By law, numbers have to be listed the same way.

“N” is for nitrogen. Nitrogen is always the first number in labeling. Your plants need nitrogen to make chlorophyll and for strong leaf growth. Give your plant too much nitrogen and plants will produce the most beautiful, strong foliage you’ve ever seen — but very few flowers. Nitrogen is great on lawns for “greening up” in the spring.

“P” is for phosphorus and is always the second number. Plants need phosphorus for bright blooms, increased fruit development, and strong roots.

“K” is for potassium, or potash, and is always the third number on the label. Potassium is utilized in the plant for strong structure (stems and leaves) and also promotes general health, helps plants fight disease and stress, and improves the quality of fruits and vegetables. It also reduces a plant’s need for water by slowing loss of water through the leaves.

And what about those numbers? What do they mean? These numbers stand for the percentage of nitrogen, phosphate, and potash or potassium in the fertilizer, and are always given in that same order — always nitrogen first, then phosphate, then potash. Keep this in mind when you compare sizes and prices of fertilizers. As an example, 100 pounds of 10-5-10 would always contain 10 pounds (10 percent) nitrogen, 5 pounds (5 percent) phosphate, and 10 pounds (10 percent) potash or potassium. See? It’s almost easy!

Q: I think I missed a question from you which involved getting rid of the day lilies that have reseeded themselves and are living in your lawn.

A: Have you tried using Roundup with the applicator wand? You will have to walk around the lawn and spot-spray the unwanted lilies, being very careful to spray only the unwanted plants. This should kill the plant foliage as well as the root — if not, try a second application.

North Shore Gardener by Barbara Barger is a feature of Friday’s Living section. Reach Barbara at or write c/o Gloucester Daily Times, 36 Whittemore St., Gloucester, MA 01930. Previous North Shore Gardener columns can be found at