Fertilizer: By the Numbers

Have you ever looked on a fertilizer box and wondered what the numbers mean? The gardening department Team Members at Friedman’s Home Improvement are frequently asked questions about fertilizer, so we thought we’d address it here in our blog.

Like any list of ingredients you would see on a packaged food label, fertilizers are rated with a three number rating system. These three numbers are based off the N-P-K ratios, which shows how much Nitrogen, Phosphorus and Potassium (Potash) is in the mix. These numbers are percentages of the total ingredients in the bag, so if it reads 5-5-5 — like it does in Whitney Farms® Life Link® All-Purpose Plant Food (5-5-5) — there are equal amounts of each ingredient in the bag at 5% each.

To sound like a fertilizer pro, you will need to learn which numbers are best suited to what you are growing. For example, if you see lawn fertilizer numbers with an NPK rating of 21-7-14, it means that Nitrogen has the highest concentration. It is 3 times the amount of phosphorus. Phosphorus is only half of the Potassium amount. Technically, this would be called a 3-1-2 ratio. This NPK ratio is perfect for a stressed lawn that is preparing for winter or extreme heat and requires more potassium.

Use this helpful trick to help you identify the proper blend each time you need to buy lawn fertilizer. Look at any set of fertilizer ratios on a label. Notice how the numbers relate to each other by size:

  • 21-7-14 is Big – Small – Medium — is great for a stressed lawn and will save you down the road from bald spots and weed invasion.
  • 21-3-3 is Big – Small – Small — which is great for normal, healthy, established lawns.
  • 6-20-20 is Small – Big – Big — is for brand new lawns to help them settle in nicely.
  • 21-0-0 is Big – Zero – Zero — is all about nitrogen, which helps essential growth, is easily flushed through the soil, and produces lush green and tender leaves.

We hope this little guide helps you fertilize by the numbers, but if you still have questions about which numbers are best suited to your plants, ask any of our friendly and helpful staff. Be sure to check out this week’s ad for a coupon to save 60% off Whitney Farms® Life Link® All-Purpose Plant Food (5-5-5).

Friedman’s Home Improvement: Lowest Price, Local Advice.

Local Business Sonoma County

Go Local

Thank you for Shopping Local. When you support us, you’re supporting your…

Learn More »

Never Undersold. Lowest Price. Period.

Never Undersold

We Guarantee the Lowest Price, Period. If you find an identical item at a lower…

Learn More »


Expert Advisor

Your exclusive source for expert advice on your Home Improvement Projects….

Learn More »

Express Lumber Yard

Express Yard

Drive-Thru Lumber Yard, where your vehicle is your shopping cart….

Learn More »

Express Delivery

7 Day Express Delivery

7 Days a week. GUARANTEED….

Learn More »

Greener Choice

Greener Choice

Greener Choice products are third party certified to be healthy for your family…

Learn More »

Store Information

Friedman's Home Improvement proudly services all of the North Bay with convenient locations in Santa Rosa, Petaluma, Sonoma, and Ukiah.

Mon thru Fri 6am - 8pm
Sat 7am - 7pm
Sun 8am - 7pm

Get Directions »

Double Click Collective Media Yield Manager Yield Manager Double Click Collective Media Yield Manager