Lawn Fertilizer: How to Read the Bag, Pick a Type and Apply the Right Rate

Key takeaways

• The three numbers are a legal guarantee of total nitrogen, available phosphate (P2O5) and soluble potash (K2O), not elemental P and K; multiply the middle number by 0.44 and the last by 0.83 to get the elements (Penn State Extension; 3 Pa.C.S. §6801).
• Purdue caps a single feeding at 1.0 lb of water-soluble nitrogen per 1,000 sq ft, or 2.0 lb when more than half the nitrogen is slow-release, and suggests 25 to 50 percent slow-release nitrogen for established lawns (Purdue AY-22).
• Annual nitrogen runs from 0 to 2 lb per 1,000 sq ft for buffalograss (K-State MF658) to 2 to 6 lb for St. Augustinegrass in Florida (UF/IFAS LH010); cool-season lawns take 1 to 5 lb (Purdue AY-22, Table 2).
• Ten state laws we read restrict phosphorus lawn fertilizer or flag it at the shelf; Minnesota allows it only with a soil test from the last 3 years or on new turf in its first growing season (Minn. Stat. §18C.60).
• Price per pound of nitrogen, not price per bag, compares products: in our October 2026 check the spread ran from $3.17 (Scotts Turf Builder 38-0-4, 37.9 lb) to $17.84 (Espoma Turf-tone 9-0-1, 28 lb) per lb of N (single seller listings checked Oct. 28, 2026).

What do the three numbers on a lawn fertilizer bag mean?

The three numbers are the grade: the guaranteed minimum percent by weight of total nitrogen (N), available phosphate (P2O5) and soluble potash (K2O), in that order. Pennsylvania’s fertilizer law spells out that order and form, and other states use the same model wording (3 Pa.C.S. §6801, definition of guaranteed analysis). A 50 lb bag of 20-5-15 holds 10 lb of N, 2.5 lb of P2O5 and 7.5 lb of K2O.

That 50 lb example is the University of Tennessee’s (UT Extension W161-E). The middle and last numbers are oxides, a labeling convention: Penn State notes that P2O5 and K2O compounds do not exist in fertilizer, and converts them with two factors, % P2O5 × 0.44 = % P and % K2O × 0.83 = % K (Penn State Extension, updated Sept. 19, 2025).

Where do guides get the middle number wrong?

Some guides shorten the label to percent N, P and K, which overstates phosphorus about 2.3 times and potassium about 1.2 times. Purdue’s AY-22 says a 16-4-8 bag “contains 16 percent N, 4 percent P, and 8 percent K” (Purdue AY-22, p. 3), and Wisconsin’s DATCP fact sheet reads 10-8-15 as 10% N, 8% P and 15% K (DATCP P-DARM413). The statute and the conversion factors give the figures below.

Grade on the bag	What some guides say	What the label guarantees	Elemental P and K (× 0.44, × 0.83)	Source
16-4-8	16% N, 4% P, 8% K	16% N, 4% P2O5, 8% K2O	1.76% P, 6.64% K	Purdue AY-22; Penn State
10-8-15	10% N, 8% P, 15% K	10% N, 8% P2O5, 15% K2O	3.52% P, 12.45% K	Wisconsin DATCP; Penn State
20-5-15, 50 lb bag	n/a	10 lb N, 2.5 lb P2O5, 7.5 lb K2O	1.1 lb P, 6.2 lb K	UT W161-E

The distinction matters for compliance as well as chemistry. Vermont and Maine define a phosphorus fertilizer by its phosphate content: more than 0.67 percent available phosphate by weight (10 V.S.A. §1266b(a)(6); 38 M.R.S. §419(1)(A-4)). Read the middle number as P2O5 when you check a bag against those rules.

What else does the label have to show?

Beyond the grade, Pennsylvania requires six items on every bag: brand and grade, the guaranteed analysis, what the material was derived from, directions for use, the guarantor’s name and address, and net weight (3 Pa.C.S. §6805(a)). The “derived from” line and the nitrogen breakdown tell you how fast the bag works, which the three numbers alone do not.

Label line	What it tells you	How to use it
Grade, e.g. 32-0-4	Percent N, P2O5, K2O	Divide your nitrogen target by the first number ÷ 100 to get pounds of product
Nitrogen breakdown (ammoniacal, urea, water-insoluble, slowly available)	How much N is quick-release	Purdue’s 1.0 lb cap applies to the water-soluble share; more than 50% slow-release allows up to 2.0 lb
Derived from	Urea, methylene urea, polymer-coated urea, sulfur-coated urea, biosolids	Coated and methylene urea sources release over weeks; urea and ammonium sulfate release in days
Directions for use and spreader settings	Coverage per bag at the maker’s rate	Back-calculate the nitrogen rate: bag lb × N% ÷ (coverage ÷ 1,000)
Turf warning statement (Pennsylvania)	No application near water or before heavy rain; sweep granules off pavement	Required on turf bags of 1 lb or more under §6805(g)

Which nitrogen sources are in lawn fertilizer, and how fast do they release?

Quick-release sources such as urea, ammonium sulfate and potassium nitrate dissolve in water and green turf within a few days for nitrate forms or 7 to 10 days for ammonium forms; slow-release sources such as polymer-coated urea, sulfur-coated urea, methylene urea and biosolids feed for weeks and burn less (Purdue AY-22, Table 1). Most lawn bags blend both.

Salt index measures burn risk. The University of Tennessee rates each source per unit of nitrogen against sodium nitrate: urea 1.7 (moderate), ammonium sulfate 3.3 (high), sulfur-coated urea 0.7, Milorganite 0.7, ureaform or methylene urea 0.3 and IBDU 0.2 (low) (UT W161-E). The chart plots those values; the table holds them with each source’s release mechanism.

Salt index is a lab ranking, though: in a 2026 field trial on bermudagrass, monoammonium and diammonium phosphate burned the most at high rates while ammonium sulfate burned none, which is why our answer to can you over fertilize your lawn puts the dose ahead of the salt number.

1. Potassium nitrate5.30
2. Ammonium sulfate3.30
3. Ammonium nitrate3.20
4. Urea1.70
5. Sulfur-coated urea0.70
6. Milorganite (biosolids)0.70
7. Ureaform / methylene urea0.30
8. IBDU0.20

Source: University of Tennessee Extension W161-E High 2.6 or more, moderate 1.0 to 2.5, low under 1.0. Values per unit of nutrient.

Show the numbers

	Salt index per unit of N
Potassium nitrate	5.30
Ammonium sulfate	3.30
Ammonium nitrate	3.20
Urea	1.70
Sulfur-coated urea	0.70
Milorganite (biosolids)	0.70
Ureaform / methylene urea	0.30
IBDU	0.20

Nitrogen source	N content	Release	What controls release	Salt index per unit N	Source
Urea	45 to 46%	Quick	Dissolves; urease converts it to ammonium within about 3 days	1.7 (moderate)	UT W161-E; UF/IFAS, 1986
Ammonium sulfate	21% (24% sulfur)	Quick	Water-soluble; strongest acidifier listed	3.3 (high)	UT W161-E
Ammonium nitrate	33%	Quick	Water-soluble; nitrate can leach	3.2 (high)	UT W161-E
Potassium nitrate	13% N, 44% K2O	Quick	Water-soluble	5.3 (high)	UT W161-E
Sulfur-coated urea (SCU)	32%	Slow	Water moves through the sulfur coat; microbes and hydrolysis	0.7 (low)	UT W161-E
Polymer-coated urea (PCU)	38%	Slow	Diffusion through a plastic coat	not listed	UT W161-E
Ureaform or methylene urea	38%	Slow	Soil microbes break the chains; longer chains release slower	0.3 (low)	UT W161-E
IBDU	31%	Slow	Hydrolysis, not microbes; faster when warm	0.2 (low)	UT W161-E
Biosolids (Milorganite)	6% N, 4% P2O5	Slow	Soil microbes; little release in cold soil	0.7 (low)	UT W161-E

Temperature splits the slow sources. Natural organics and ureaform depend on soil microbes, so they release little in cold or waterlogged soil, while IBDU depends on water and speeds up as soil warms (UT W161-E). That is why Purdue prefers a product with nearly 100 percent water-soluble nitrogen for cool-season feedings from early October to early December (Purdue AY-22).

How much lawn fertilizer should you put down?

Plan in pounds of actual nitrogen per 1,000 sq ft, not pounds of product. Purdue’s normal target is 0.5 to 1.0 lb of N per feeding, never more than 1.0 lb of water-soluble N at once, and up to 2.0 lb only when more than half the nitrogen is slow-release (Purdue AY-22). The yearly total depends on the grass.

Three adjustments change the yearly total. Lawns where clippings are bagged need 25 to 50 percent more nitrogen, shaded lawns need up to 50 percent less and no more than 2.0 lb a year, and lawns fertilized regularly for more than 10 years can drop a feeding (Purdue AY-22). New lawns may need up to 50 percent more in their first 12 to 18 months.

1. Buffalograss0
2. Centipedegrass1
3. Bahiagrass1
4. Zoysiagrass (Tex.)1
5. Cool-season, moderate (Purdue)2
6. Bermudagrass (Ga.)2
7. St. Augustinegrass (south Fla.)4
8. Bermudagrass (south Fla.)5

Source: K-State MF658; Clemson HGIC 1215; UF/IFAS LH006, LH010, LH007; Texas A&M SCSC-PU-279; Purdue AY-22; UGA Same figures as the grass table on this page.

Show the numbers

	Low end	High end
Buffalograss	0	2
Centipedegrass	1	2
Bahiagrass	1	2
Zoysiagrass (Tex.)	1	3
Cool-season, moderate (Purdue)	2	4
Bermudagrass (Ga.)	2	5
St. Augustinegrass (south Fla.)	4	6
Bermudagrass (south Fla.)	5	7

Grass	Annual N (lb per 1,000 sq ft)	Note	Source
Tall fescue, Kentucky bluegrass, perennial ryegrass (moderate care)	2 to 4	1 to 5 across Purdue’s four care levels	Purdue AY-22, Table 2
Tall fescue, North Carolina basic program	about 3	1 lb each in mid-September, November and February	NC State AG-367
Shaded fine fescue	up to 2	Half the sunny-lawn rate	Purdue AY-22
Bermudagrass, Georgia	2 to 5	Starts when 4-inch soil holds 65°F	UGA bermudagrass calendar
Bermudagrass, south Florida	5 to 7	Year-round growth	UF/IFAS LH007
Zoysiagrass, Texas	1 to 3	Established lawns	Texas A&M SCSC-PU-279
St. Augustinegrass, Florida	2 to 4 north, 2 to 5 central, 4 to 6 south	2 to 6 feedings a year by region	UF/IFAS LH010, Table 2
Centipedegrass	1 to 2	More than 2 lb builds thatch	Clemson HGIC 1215
Bahiagrass, Florida	1 to 2	Same range in every Florida region	UF/IFAS LH006
Buffalograss	0 to 2	June and July only	K-State MF658

When each feeding goes on, month by month and by state blackout date, is covered in our lawn care schedule by grass type. Grass-specific programs are on the bermuda grass and St. Augustine grass guides.

How do you turn pounds of nitrogen into pounds of product?

Divide the nitrogen you want by the first number on the bag, written as a decimal, then multiply by the lawn’s area in thousands of square feet. Purdue’s worked example: 0.5 lb of N on 5,500 sq ft from an 18-0-10 product is 0.5 ÷ 0.18 = 2.78 lb per 1,000 sq ft, times 5.5, or 15.29 lb (Purdue AY-22).

Product (grade)	Product for 1 lb N per 1,000 sq ft	For 5,000 sq ft	Bags	N delivered at the bag’s own coverage
Scotts Turf Builder 38-0-4, 12.64 lb (38-0-4)	1 ÷ 0.38 = 2.63 lb	13.2 lb	1.04 of a 12.64 lb bag	12.64 × 0.38 ÷ 4 = 1.20 lb N
Pennington Full Season 32-0-5, 11.2 lb (32-0-5)	1 ÷ 0.32 = 3.12 lb	15.6 lb	1.40 of a 11.2 lb bag	11.2 × 0.32 ÷ 4 = 0.90 lb N
Milorganite 6-4-0, 32 lb (6-4-0)	1 ÷ 0.06 = 16.67 lb	83.3 lb	2.60 of a 32 lb bag	32 × 0.06 ÷ 2.5 = 0.77 lb N

The last column is the check most buyers skip. Spread at its printed 4,000 sq ft, a 12.64 lb bag of Scotts Turf Builder 38-0-4 puts down 1.20 lb of N per 1,000 sq ft, about 0.96 lb of it quick-release, because only 7.6 of its 38 percent is slowly available (Scotts label, SKU 23500). That sits just under Purdue’s 1.0 lb soluble cap but above the 0.9 lb total-N cap that Maryland and New Jersey set for homeowners (Md. Code, Agric. §8-803.5(f); N.J. P.L.2010, c.112); there, spread the bag over about 5,300 sq ft instead.

Lawn area (sq ft)Product (October 2026 price per lb of N)Scotts Turf Builder 38-0-4, 37.9 lb (38-0-4), $3.17 per lb NPennington Full Season 32-0-5, 33.6 lb (32-0-5), $4.67 per lb NScotts Turf Builder 38-0-4, 12.64 lb (38-0-4), $5.20 per lb NScotts Turf Builder 32-0-4, 12.5 lb (32-0-4), $6.75 per lb NScotts WinterGuard 32-0-10, 10 lb (32-0-10), $7.49 per lb NPennington Full Season 32-0-5, 11.2 lb (32-0-5), $7.81 per lb NEspoma Lawn Food 15-0-5, 40 lb (15-0-5), $8.33 per lb NMilorganite 6-4-0, 32 lb (6-4-0), $10.40 per lb NScotts Starter 24-25-4, 15 lb (24-25-4), $10.41 per lb NEspoma Turf-tone 9-0-1, 28 lb (9-0-1), $17.84 per lb NNitrogen per 1,000 sq ft this feeding1.0 lb (Purdue's cap for quick-release N)0.75 lb0.5 lb0.9 lb total N (Maryland and New Jersey homeowner cap)

Pounds of nitrogen to apply

5.00

Pounds of a 32-0-4 product

15.6

Pounds of a 38-0-4 product

13.2

Pounds of a 6-4-0 organic product

83.3

Product cost for this feeding$15 to $15

Cost = area × nitrogen rate × the product's price per lb of N from our dated listings. Pounds of product: divide the nitrogen line by the bag's first number ÷ 100.

Which lawn fertilizers cost the least per pound of nitrogen?

Divide the bag price by the pounds of nitrogen in it: bag weight × first number ÷ 100. On that basis the products below ran from $3.17 to $17.84 per lb of N at the listings we checked in October 2026, and the cheapest per bag was not always the cheapest per pound of nitrogen.

1. Scotts Turf Builder 38-0-4, 37.9 lb3.17
2. Pennington Full Season 32-0-5, 33.6 lb4.67
3. Scotts Turf Builder 38-0-4, 12.64 lb5.20
4. Scotts Turf Builder 32-0-4, 12.5 lb6.75
5. Scotts WinterGuard 32-0-10, 10 lb7.49
6. Pennington Full Season 32-0-5, 11.2 lb7.81
7. Espoma Lawn Food 15-0-5, 40 lb8.33
8. Milorganite 6-4-0, 32 lb10.40
9. Scotts Starter 24-25-4, 15 lb10.41
10. Espoma Turf-tone 9-0-1, 28 lb17.84

Source: Maker labels and the dated seller listings in the product table Price ÷ (bag lb × first number ÷ 100). Single listings; shelf prices change.

Show the numbers

	$ per lb of N
Scotts Turf Builder 38-0-4, 37.9 lb	3.17
Pennington Full Season 32-0-5, 33.6 lb	4.67
Scotts Turf Builder 38-0-4, 12.64 lb	5.20
Scotts Turf Builder 32-0-4, 12.5 lb	6.75
Scotts WinterGuard 32-0-10, 10 lb	7.49
Pennington Full Season 32-0-5, 11.2 lb	7.81
Espoma Lawn Food 15-0-5, 40 lb	8.33
Milorganite 6-4-0, 32 lb	10.40
Scotts Starter 24-25-4, 15 lb	10.41
Espoma Turf-tone 9-0-1, 28 lb	17.84

Product	Grade	Nitrogen derived from	Bag / labeled coverage	lb N per 1,000 sq ft at label rate	Price, seller, date	$ per lb N
Scotts Turf Builder Lawn Food (new formula, 12.64 lb)	38-0-4	Urea; polymer-coated sulfur-coated urea (7.6% slowly available N); 20% of N slow-release	12.64 lb / 4,000 sq ft	1.20	$24.99, scottsmiraclegro.com, Oct. 28, 2026	$5.20
Scotts Turf Builder Lawn Food (new formula, 37.9 lb)	38-0-4	Same label as the 12.64 lb bag; 20% of N slow-release	37.9 lb / 12,000 sq ft	1.20	$45.60, Walmart.com, Oct. 28, 2026	$3.17
Scotts Turf Builder Lawn Food (previous formula, SKU 22305)	32-0-4	Methylene ureas, urea, ammonium sulfate (9% slowly available N); 28% of N slow-release	12.5 lb / 5,000 sq ft	0.80	$26.99, scottsmiraclegro.com, Oct. 28, 2026	$6.75
Scotts Turf Builder WinterGuard Fall Lawn Food	32-0-10	Urea, methylene ureas, ammonium sulfate (6.8% slowly available N); 21% of N slow-release	10 lb / 4,000 sq ft	0.80	$23.98, Walmart.com, Oct. 28, 2026	$7.49
Scotts Turf Builder Starter Food for New Grass	24-25-4	Methyleneureas, urea, ammonium phosphate (6.2% slowly available N; 2015 label file); 26% of N slow-release	15 lb / 5,000 sq ft	0.72	$37.49, scottsmiraclegro.com, Oct. 28, 2026	$10.41
Pennington Full Season Lawn Fertilizer (11.2 lb)	32-0-5	Urea, polymer-coated urea, ammonium sulfate (12% controlled-release N); 38% of N slow-release	11.2 lb / 4,000 sq ft	0.90	$27.99, Walmart.com, Oct. 28, 2026	$7.81
Pennington Full Season Lawn Fertilizer (33.6 lb)	32-0-5	Same label as the 11.2 lb bag; 38% of N slow-release	33.6 lb / 12,000 sq ft	0.90	$50.21, Walmart.com, Oct. 28, 2026	$4.67
Vigoro Lawn Fertilizer 30-0-4 (11.2 lb)	30-0-4	Urea, polymer-coated urea (10% controlled-release N); 33% of N slow-release	11.2 lb / 4,000 sq ft	0.84	Not confirmed (search snippet only)	n/a
Milorganite 6-4-0 (32 lb)	6-4-0	Biosolids (4% water-insoluble, slowly available N); 67% of N slow-release	32 lb / 2,500 sq ft	0.77	$19.97, Walmart.com, Oct. 28, 2026	$10.40
Espoma Lawn Food 15-0-5 (40 lb)	15-0-5	Poultry manure, methylene urea, ammonium sulfate, urea (7.7% slow-release N); 51% of N slow-release	40 lb / 12,000 sq ft (computed)	0.50	$49.99, Bay Gardens, Oct. 28, 2026	$8.33
Espoma Organic Turf-tone All Season Lawn Food 9-0-1 (28 lb)	9-0-1	Feather, meat and blood meal, poultry manure (7.7% slow-release N); 86% of N slow-release	28 lb / 5,000 sq ft	0.50	$44.95, Sod Solutions, Oct. 28, 2026	$17.84

Big bags and high-analysis grades win on this measure. The 37.9 lb Scotts Turf Builder 38-0-4 at $45.60 works out to $3.17 per lb of N, against $5.20 for the 12.64 lb bag of the same product; Milorganite’s 32 lb bag at $19.97 holds only 1.92 lb of N, or $10.40 a pound. Scotts sells two Turf Builder Lawn Food formulas side by side as of October 2026: the new 38-0-4 (SKU 23500) and the previous 32-0-4 (SKU 22305), so read the grade, not the brand name, before you set the spreader (ScottsMiracle-Gro).

Is 10-10-10 or starter fertilizer good for an established lawn?

Usually not, unless a soil test shows low phosphorus or potassium. At 1 lb of N per 1,000 sq ft, 10-10-10 also drops 1 lb of P2O5 and 1 lb of K2O on the lawn every feeding. Purdue tells homeowners to avoid general-purpose garden grades such as 12-12-12 on established turf (Purdue AY-22), and Illinois suggests 3-0-2 or 4-0-2 ratios (Illinois Extension).

Grade	Product for 1 lb N per 1,000 sq ft	P2O5 applied	Elemental P applied (× 0.44)	K2O applied
32-0-4	3.1 lb	0.00 lb	0.00 lb	0.12 lb
24-25-4 (starter)	4.2 lb	1.04 lb	0.46 lb	0.17 lb
16-4-8	6.2 lb	0.25 lb	0.11 lb	0.50 lb
10-10-10	10.0 lb	1.00 lb	0.44 lb	1.00 lb
6-4-0 (biosolids)	16.7 lb	0.67 lb	0.29 lb	0.00 lb

Compare those numbers with the state caps. Pennsylvania lets organic-based products carry phosphorus only up to 0.25 lb of P per 1,000 sq ft per application and 0.5 lb a year (3 Pa.C.S. §6813(a)(3)); a 1 lb N feeding of a 6-4-0 organic product supplies about 0.29 lb of P, just over that line, so the rate has to drop to roughly 0.85 lb N to stay under it.

Starter fertilizer is the legal exception almost everywhere: Minnesota, Wisconsin, Washington, New York and Vermont all allow phosphorus on new seed or sod in its first growing season (Minn. Stat. §18C.60; 10 V.S.A. §1266b). Seeding steps are in how to plant grass seed, and our overseeding guide gives Purdue’s starter rates.

Which states restrict phosphorus in lawn fertilizer?

Of the state laws we read at the source in October 2026, nine limit applying or selling phosphorus lawn fertilizer and Maine requires a shelf warning sign. All ten carve out new seed or sod in some form, and nine exempt lawns whose soil test shows a need; the test must be no older than 18 months in Vermont and 3 years in Minnesota, Wisconsin, Washington, New Jersey, Maryland and Virginia.

State	Law (source)	Type	What is restricted	Exemptions	Applies to
Minnesota	Minn. Stat. §18C.60, subd. 2	use ban	Applying fertilizer containing phosphorus to turf	Soil or tissue test within 3 years shows P is insufficient; first growing season of new seed or sod; golf courses under trained staff	Everyone
Wisconsin	Wis. Stat. §94.643 (DATCP P-DARM413, April 2022)	use and display ban	Applying P-labeled turf fertilizer; retail display of it	Growing season the turf is established by seed or sod; lab soil test within 36 months shows a deficiency	Everyone
Washington	RCW 15.54.500	use and sale ban	Applying or selling P-labeled turf fertilizer; applying it on frozen ground	Establishing or repairing grass by seed or sod in that growing season; soil test within 36 months shows a deficiency	Everyone
New York	N.Y. ECL §17-2103(1)	use ban	Applying phosphorus fertilizer to lawn or non-agricultural turf	Soil test shows more P is needed; newly established lawn in its first growing season	Everyone, including hired applicators
New Jersey	N.J. P.L.2010, c.112, §3(d) to (e)	use ban	Applying phosphorus fertilizer to turf	Soil test within 3 years; establishing vegetation for the first time; reestablishing or repairing turf; subsurface placement; manipulated manure at no more than 0.25 lb P per 1,000 sq ft	Everyone
Maryland	Md. Code, Agric. §8-803.5(e)	use ban	Applying phosphorus fertilizer to turf	Soil test within 3 years; establishing vegetation for the first time; reestablishing or repairing turf	Everyone
Pennsylvania	3 Pa.C.S. §6804(a)(2) and §6813(a)(3)	product and rate rule	Distributing turf fertilizer with P to consumers; applying P to turf	Labeled for establishing or repairing turf; natural organic or organic-based products at no more than 0.25 lb P per 1,000 sq ft per application and 0.5 lb a year	Everyone
Virginia	Va. Code §3.2-3607(F)	sale ban	Registering, selling or using lawn maintenance fertilizer that contains phosphorus (since Dec. 31, 2013)	“Lawn fertilizer” for new seed or sod in its first season, repair or renovation, or a soil test within 3 years showing a deficiency (defined in §3.2-3600); manipulated manure, yard waste compost and sewage-sludge products	Everyone
Vermont	10 V.S.A. §1266b(b)	use ban	Applying phosphorus fertilizer to turf	Soil test within 18 months shows a deficiency; starter fertilizer in the first growing season of new seed or sod	Everyone
Maine	38 M.R.S. §419(1)(A-4) and (2)(B)	retail sign rule	Selling P fertilizer for lawns without a posted state-approved warning sign	Soil test shows P is needed; new lawn, reseeding or overseeding	Retailers

Several of the same laws add rules that apply to every bag. Washington bars phosphorus turf fertilizer on frozen ground (RCW 15.54.500); Pennsylvania requires consumer turf fertilizer to carry at least 20 percent enhanced-efficiency nitrogen (3 Pa.C.S. §6804(a)(1)); Vermont bars applying any turf fertilizer whose nitrogen is less than 15 percent slow-release (10 V.S.A. §1266b(a)(5) and (c)). Dated blackout windows are on our lawn care schedule.

Lawn companies applying for hire can face different dates: New Jersey lets professional applicators fertilize turf until Dec. 1 rather than Nov. 15 (N.J. P.L.2010, c.112, §2(b)). Licensing is covered on our pesticide applicator license page.

This page is general information, not legal advice. Fertilizer laws change; confirm the current rule with your state department of agriculture before you buy or apply.

Are organic lawn fertilizers like Milorganite better?

Organic fertilizers burn less and feed slowly, but they carry little nitrogen and need warm, biologically active soil to release it. Milorganite is 6-4-0 with a salt index of 0.7 per unit of N against 1.7 for urea (UT W161-E), and it takes more than 5 times as much product as a 32-0-4 bag to deliver the same nitrogen.

At 1 lb N per 1,000 sq ft on 5,000 sq ft	6-4-0 biosolids	32-0-4 synthetic	Source
Product needed	83.3 lb	15.6 lb	Arithmetic: 5 ÷ 0.06 and 5 ÷ 0.32
P2O5 applied with it	3.3 lb (1.47 lb P)	0	Arithmetic; Penn State factor 0.44
Salt index of the nitrogen source	0.7 (biosolids)	1.7 if the N is urea	UT W161-E
Release in cold soil	Little: microbes inactive	Urea is water-soluble; coated shares vary	UT W161-E

That bulk is the cost. At 1 lb of N per 1,000 sq ft, a 5,000 sq ft lawn needs 83 lb of 6-4-0 against 16 lb of 32-0-4, and the price per pound of nitrogen in our product table reflects it. Illinois lists alfalfa, cottonseed meal, seaweed, bone meal, blood meal and poultry, cow and horse manure as organic sources (Illinois Extension).

Do biosolids fertilizers contain PFAS?

Biosolids, the treated sewage sludge in products such as Milorganite, are under review for PFAS. On Jan. 14, 2025, the EPA released a draft risk assessment finding that human health risks may exceed its thresholds in some modeled farm scenarios when land-applied sludge contains 1 part per billion of PFOA or PFOS; the findings are preliminary and focus on people living on or near affected farms (EPA fact sheet, January 2025).

The same fact sheet notes that bagged biosolids are sold to the public and often used on lawns and home gardens (EPA). Maine has gone furthest: since 2022 its law bars selling or distributing fertilizer or compost made with municipal sludge in the state (38 M.R.S. §1306(7)). Milorganite’s maker reports that 2026 tests for PFOA and PFOS in its products averaged 5.4 parts per billion, against limits under 20 ppb in several states, and its FAQ says the product is not sold in Connecticut and Maine (Milorganite safety page; Milorganite FAQ).

Granular or liquid lawn fertilizer: which should you use?

Granular fertilizer suits most homeowners because it can carry slow-release nitrogen; most liquid lawn fertilizer is quick-release, because most slow-release sources cannot be mixed with water. Liquids green up fast but need smaller, more frequent feedings (Purdue AY-22, Table 1). Triazone, a clear liquid made from urea, formaldehyde and ammonia, is one slower liquid source (UT W161-E).

Factor	Granular	Liquid	Source
Slow-release nitrogen possible	Yes: coated urea, methylene urea, biosolids	Mostly no	Purdue AY-22
Ammonia loss from urea in a lab study	1 to 55% of N applied	2 to 26% of N applied	UF/IFAS (Augustin and Peacock), 1986
Burn risk	Low for slow-release; water quick-release in	Leaf contact; follow label dilution	Purdue AY-22
Equipment	Rotary or drop spreader, calibrated	Hose-end or tank sprayer	Penn State Extension
Pavement cleanup rule	Sweep granules back onto turf	Pennsylvania’s sweep-back label statement does not apply to liquids	3 Pa.C.S. §6805(g)(4)

Too much liquid fertilizer burns turf the same way granules do, because the nitrogen is all water-soluble. Purdue’s per-feeding cap of 1.0 lb of water-soluble N per 1,000 sq ft applies to liquids in full (Purdue AY-22), and Pinellas County, Fla., caps liquid feedings at 0.5 lb of nitrogen per 1,000 sq ft against 1 lb for granular products that are at least 50 percent slow-release (Pinellas County fertilizer ordinance).

How do you apply lawn fertilizer without burning the grass?

Burn comes from too much soluble salt on wet leaves, so the fixes are rate, spread and water. Keep quick-release nitrogen at or under 1.0 lb per 1,000 sq ft, split the dose into two passes at right angles, and water urea in: University of Florida turf specialists found 1/8 to 1/4 inch of water usually washes it into the thatch and soil (UF/IFAS, Florida Green, 1986).

1. Measure the lawn in square feet and divide by 1,000. A 50 by 100 ft front yard is 5,000 sq ft, or 5 units.
2. Pick a target of 0.5 to 1.0 lb of N per 1,000 sq ft and work out pounds of product: target ÷ (first number ÷ 100) × units (Purdue AY-22).
3. Set the spreader to the bag’s half-rate setting. LSU warns that half the dial number is not half the rate, because spreader scales are never linear (LSU AgCenter).
4. Spread the first half in parallel strips, then the second half at right angles; Penn State says the grid masks skips and overlaps that cause striping (Penn State Extension, April 2025).
5. Sweep or blow granules off driveways and walks back onto the turf, which New Jersey and Pennsylvania require (N.J. P.L.2010, c.112, §2(a)(2); 3 Pa.C.S. §6813(b)(1)).
6. Water in quick-release and urea products with 1/8 to 1/4 inch within a day; field tests on turf averaged 20 to 30 percent nitrogen loss as ammonia gas after urea, and about 95 percent of the loss came within 7 days (UF/IFAS, 1986).
7. Skip dormant, drought-stressed or frozen turf (Purdue AY-22); Wisconsin counts ground as frozen when you cannot dig 6 to 8 inches (Wisconsin DATCP).

Calibrate once a season with a catch test: Penn State runs the spreader over a 50 to 100 ft strip with 5 to 10 lb of product in the hopper and weighs what is left (Penn State Extension). If the lawn needs weed control as well, a weed-and-feed product is a pesticide with its own EPA registration number, and its label, not the fertilizer math, sets the rate. Weed-specific choices are on our lawn weed killer guide.

Which lawn fertilizer should you buy?

Start from the soil test and the grass, then pick the grade, the slow-release share and the rate. The table turns the published thresholds into choices; the flowchart below it holds the same logic. If you have no recent soil test, our soil test guide explains how to get one before you buy anything with phosphorus or lime.

If your situation is	Do this	Why (source)
Established lawn, no soil test, in MN, WI, WA, NY, NJ, MD, PA, VA or VT	Buy a lawn grade with a 0 middle number, such as 38-0-4, 32-0-5 or 30-0-4	Phosphorus is restricted without a test (Minn. Stat. §18C.60)
Seeding or sodding a new lawn	Use a starter grade with phosphorus in the first growing season only	New-turf exemption (10 V.S.A. §1266b(b)(1)(B); RCW 15.54.500)
Soil test shows low phosphorus or potassium	Apply the P2O5 and K2O the lab recommends; a complete grade is fine	Soil-test exemption (Md. Code, Agric. §8-803.5(e); Purdue AY-22)
Want 1 lb of N or more in one pass	Choose a product with more than 50% slow-release N; cap at 2.0 lb	Purdue AY-22
Quick-release product (mostly urea or ammonium sulfate)	Cap at 1.0 lb N per 1,000 sq ft and water in 1/8 to 1/4 inch	Purdue AY-22; UF/IFAS, 1986
Homeowner in Maryland or New Jersey	No more than 0.7 lb water-soluble and 0.9 lb total N per feeding, 20% or more slow-release	Md. Code, Agric. §8-803.5(f)
Cool-season lawn, October to early December	Use nearly 100% water-soluble N at 0.5 to 0.75 lb about every 3 weeks	Cold soil slows microbial release (Purdue AY-22)
Shaded lawn	Halve the rate; 2.0 lb N a year at most	Purdue AY-22
Clippings bagged every mowing	Add 25 to 50% to the yearly nitrogen	Purdue AY-22
Want an organic product	Expect about 5 times the bag weight of a 32-0-4 for the same N, and feed only into warm soil	UT W161-E
Live in Maine	Biosolids-based fertilizer cannot be sold or distributed in the state	38 M.R.S. §1306(7)

1. 1Are you seeding or sodding a new lawn this season?

   YesUse a starter grade with phosphorus for the first growing season only (allowed under MN, WI, WA, NY and VT law).

   NoGo to the next question

2. 2Does a soil test from the last 3 years show low phosphorus or potassium?

   YesApply the P2O5 and K2O the lab recommends; a complete grade is allowed under the soil-test exemptions.

   NoGo to the next question

3. 3Do you want to apply 1 lb of nitrogen or more per 1,000 sq ft in one pass?

   YesChoose a bag with more than 50 percent slow-release nitrogen and stay at or under 2.0 lb (Purdue AY-22).

   NoGo to the next question

4. 4Is it a cool-season lawn between October and early December?

   YesUse a mostly water-soluble grade at 0.5 to 0.75 lb N about every 3 weeks (Purdue AY-22).

   NoGo to the next question

5. 5Do you prefer an organic or biosolids product?

   YesBudget for about 5 times the bag weight of a 32-0-4, apply into warm soil, and check state rules (Maine bars biosolids products).

   NoBuy a lawn grade with a zero middle number and 25 to 50 percent slow-release nitrogen, apply 0.5 to 1 lb N per 1,000 sq ft, and compare brands by price per pound of nitrogen.

Source: Purdue AY-22; Minn. Stat. §18C.60; 10 V.S.A. §1266b; 38 M.R.S. §1306

Recap	Number	Source
Max water-soluble N per feeding	1.0 lb per 1,000 sq ft	Purdue AY-22
Max N per feeding, more than 50% slow-release	2.0 lb per 1,000 sq ft	Purdue AY-22
Phosphate to phosphorus	× 0.44	Penn State
Potash to potassium	× 0.83	Penn State
Water to move urea into soil	1/8 to 1/4 inch	UF/IFAS, 1986