Lawn Fertilizer Study Guide: When and Why

Lawn fertilizer leads to greener grass
Lawn fertilizer leads to greener grass

You’re staring out your window, thinking maybe I need to buy lawn fertilizer, getting ready to buy the first cheap fertilizer you see at your local home improvement store. Before you do that, here are the lawn fertilizer basics you should use to inform your purchasing decision.

Lawn Fertilizer Numbers: Up, Down, and All-Around

There are three numbers on a fertilizer label that stand for the percentages of nitrogen, phosphorous, and potassium found in the product. Each nutrient provides a specific value for your lawn.

Nitrogen (N) promotes plant growth, leaf development, and the green color to strike envy into the hearts of all your neighbors.

Phosphorous (P) promotes root growth and fruit/flower/seed production.

Potassium (K) promotes root development and resistance to drought and disease.

The trick is “Up, Down and All-Around.” The first number (up) promotes rapid growth, the second (down) promotes root development, and the third promotes (all-around) overall health.

When to Use Lawn Fertilizer

You should look to fertilize your lawn twice a year minimally, focusing your attention to the spring and fall.

Fertilizers with a higher nitrogen concentration are best for the spring and summer to promote growth, while fertilizers that are higher in phosphorous and potassium are best used in the fall to encourage root development.

Regardless of what time of year you’re fertilizing, we want to stress the importance of fertilizing when the ground temperature is warm enough (over 60 degrees F), which also means refraining from fertilizing any lawns that are dormant, unless your fertilizer is low in nitrogen. For some more dos and don’ts, check out HGTV.

For Atlanta, a good lawn fertilizing schedule is:

February: Pre-emergent for weed control

Late March/April: Fertilizer with nitrogen

September: Fertilizer with pre-emergent

November: Post-emergent to kill all winter annual weeds

Remember that when fertilizing, you’re encouraging new growth from your plants. You want to be mindful of the new growth as it’s sensitive to freeze damage, extreme heat, and weed control chemicals.

No matter which lawn fertilizer you end up choosing, read the label! It’ll share important safety tips and complementary actions you’ll need to take, such as how much to water.

Finding the right combination of fertilizers and NPK percentages for your lawn is daunting. If instead you’re thinking, I don’t want to mess with that, we’re happy to lend a hand.

Topics: fertilizer, lawn care, Lawn Tips