15-15-15 Fertilizer
Balanced / all-purpose15-15-15 is 15% nitrogen, 15% phosphate and 15% potash by weight. To apply 1 lb of nitrogen per 1,000 sq ft, spread 6.67 lbs of product per 1,000 sq ft; a 50-lb bag covers about 7,500 sq ft at that rate.
What 15-15-15 Means
Nitrogen (N)
15%
7.5 lb per bag
Green color and growth
Phosphate (P₂O₅)
15%
7.5 lb per bag
Root growth, new seedlings
Potash (K₂O)
15%
7.5 lb per bag
Stress, drought and cold tolerance
Pounds shown are per 50-lb bag. The N:P:K ratio simplifies to 1:1:1. The remainder of the bag is carrier, filler, and secondary nutrients.
How Much 15-15-15 to Apply
Lawn feeding is measured in pounds of nutrient per 1,000 sq ft. Here's how much product hits each common target.
| Target | Product / 1,000 sq ft | Per acre | 50-lb bag covers | Delivers (N-P-K lb) |
|---|---|---|---|---|
| 0.25 lb N | 1.67 lb | 72.6 lb | 30,000 sq ft | 0.25-0.25-0.25 |
| 0.5 lb N | 3.33 lb | 145 lb | 15,000 sq ft | 0.5-0.5-0.5 |
| 0.75 lb N | 5 lb | 218 lb | 10,000 sq ft | 0.75-0.75-0.75 |
| 1 lb N | 6.67 lb | 290 lb | 7,500 sq ft | 1-1-1 |
What It's For
A balanced fertilizer with equal N, P and K. General purpose; most useful on lawns when a soil test shows low phosphorus and potassium.
When to Use It
At seeding, or as a soil-test-driven correction.
Before You Spread It
- Several states restrict phosphorus on established lawns unless a soil test shows a need or you're seeding. Check your state's rules before using it as a routine feed.
- Phosphorus and potassium needs vary a lot from lawn to lawn. A soil test tells you whether you need them at all.
15-15-15 Calculator
Enter your lawn size to get the total amount, or change the analysis to check a different bag.
Spread 6.67 lb per 1,000 sq ft, 33.33 lb for 5,000 sq ft (0.67 bags).
Delivers 1 lb N, 1 lb P₂O₅ and 1 lb K₂O per 1,000 sq ft. Never exceed the label rate.
Common Questions
How much 15-15-15 per 1,000 sq ft?
To deliver 1 lb of nitrogen per 1,000 sq ft, apply 6.67 lbs of 15-15-15 per 1,000 sq ft, or about 290 lbs per acre. Many applications use half that or less, and the product label rate always comes first.
What is 15-15-15 fertilizer used for?
A balanced fertilizer with equal N, P and K. General purpose; most useful on lawns when a soil test shows low phosphorus and potassium.
When should I apply 15-15-15?
At seeding, or as a soil-test-driven correction.
What do the numbers 15-15-15 mean?
They're the percentages by weight of nitrogen (N), phosphate (P₂O₅) and potash (K₂O). A 50-lb bag of 15-15-15 contains 7.5 lbs of nitrogen, 7.5 lbs of phosphate and 7.5 lbs of potash; the rest is carrier and other ingredients.
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