Phosphorus Lawn Fertilizer Laws, State by State

In at least 16 states, phosphorus lawn fertilizer is restricted — in most, it's illegal to apply it to an established lawn unless a soil test shows the soil actually needs it; in a few, it's what retailers can sell that's capped — and many more counties and towns add rules on top of that. But here's the part that matters if you're laying sod: nearly every one of these laws specifically exempts new lawns and new sod. The catch most people miss is what that exemption is really telling you — that for an established lawn, phosphorus is the regulated exception, not the default, and your new install is the one window it's broadly allowed.

This is a plain-English map of where phosphorus lawn-fertilizer laws stand as of 2026, what they have in common, and what they mean for a sod project. One note before the details: this is general information, not legal advice. These laws change, and many municipalities add stricter local ordinances — always confirm the current rules for your state and town before you buy or apply.

Why these laws exist

The target is water, not lawns. Phosphorus is the nutrient that triggers algae blooms in fresh water, and when excess lawn phosphorus washes off into streams, ponds, and lakes, it feeds the eutrophication that starves those waters of oxygen and creates dead zones. It doesn't take much, and you don't have to live on the water — runoff carries it. That's why, starting with Minnesota in the early 2000s, state after state concluded the same thing: most established lawns already have plenty of phosphorus, so applying more is usually unnecessary and environmentally costly. The laws codify that conclusion.

What nearly every law says (the common structure)

The specifics vary, but the backbone is remarkably consistent across states. Phosphorus fertilizer generally may not be applied to a lawn or non-agricultural turf unless one of these is true:

• A soil test shows the soil is deficient in phosphorus.
• You're establishing a new lawn or new turf — including new sod.
• You're repairing or renovating turf after damage.

Most of these laws also share several other provisions:

• No application on impervious, frozen, or saturated ground, and any fertilizer that lands on pavement must be swept back onto the grass.
• Setbacks from water — commonly in the range of 10 to 25 feet from waterways.
• Seasonal "blackout" periods in some states, when no nitrogen or phosphorus may be applied.
• Common exemptions for agriculture, sod farms, gardens, and (often) golf courses.
• Sales and labeling rules in some states — for example, requiring retailers to display phosphorus fertilizer separately with educational signage.

If you remember one thing: on the fertilizer bag, the middle of the three N-P-K numbers is phosphorus. A "0" in the middle means zero phosphorus — and in much of the country, that's now the default product on the shelf.

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What this means for new sod

Two things, and they pull in the same direction. One important nuance: the winter blackout dates and waterfront buffers in states that have them apply even during establishment — the new-sod exemption covers the phosphorus, not the calendar or the shoreline.

First, your install is almost always exempt. Because new establishment is carved out of nearly every law, you can legally apply phosphorus when laying sod. University turfgrass research supports the exemption: new turf from seed or sod has an immature root system and, on genuinely low-phosphorus ground — especially stripped construction sites where the topsoil was hauled off and you're laying onto subsoil — may benefit from extra phosphorus to establish.

Second, "allowed" is not the same as "needed." The exemption lets you use phosphorus; it doesn't mean you should by default. Many sod installs go onto lawns whose soil has been fertilized for years and already tests high in phosphorus, where added phosphorus does nothing for the lawn and just runs off. This is why the smartest move is the same one the laws are built around: get a soil test first. If it shows you're low, use phosphorus for the install — legally and usefully. If it shows you're adequate-to-high, skip it and go low-phosphorus, which keeps you compliant not just for the install but for every feeding afterward, when phosphorus is restricted.

State by state (as of 2026)

Laws are summarized in plain language and simplified; verify the current statute and any local ordinance before applying.

Northeast

• Connecticut — Public Act 12-155 (effective January 1, 2013), codified at Conn. Gen. Stat. § 22-111yy, prohibits phosphate fertilizer, soil amendments, or compost on an established lawn — grass in place two or more growing seasons — except when an approved soil test within the previous two years shows a need, or when establishing new grass or repairing a lawn with seed or sod. Sod is named in the statute. Buffers apply even during establishment: no phosphate within 20 feet of any water body, 15 feet with a drop spreader, deflector-equipped rotary spreader, or targeted spray — and never on impervious surfaces. Products at or below 0.67% phosphate are unrestricted. Agricultural land and golf courses are exempt. The UConn Soil Nutrient Analysis Lab's explainer confirms starter fertilizer at package or soil-test rates is fine for new seeding and sodding. Under Sod™ publishes a Connecticut guide to fertilizer under new sod that walks through the new-sod exception in practice. For the Connecticut rules in full practical detail — the exception's conditions, the December 1 – March 15 blackout, and the buffer distances — see our dedicated CT phosphorus law guide.
• New York — The Nutrient Runoff Law restricts lawn fertilizer above 0.67% phosphate: legal only when establishing a new lawn (first growing season) or when a soil test shows a deficiency. No lawn fertilizer containing nitrogen, phosphorus, or potassium may be applied December 1 through April 1 — new lawn or not. No application within 20 feet of a water body unless there's a 10-foot vegetated buffer, or no closer than 3 feet with a drop spreader or deflector shield. Spills on pavement must be swept up, not hosed off. Compost is not restricted and turf farms are exempt; the DEC FAQ covers the edge cases, including bare-spot repair. Retailers must display phosphorus fertilizer separately. Suffolk and Nassau counties add their own nitrogen rules. For the establishment window itself, Under Sod™ has a New York-specific guide to what goes beneath new sod.
• New Jersey — The 2011 law is among the strictest in the nation: phosphorus is barred on lawns except by soil test or when establishing or repairing turf. Homeowners cannot apply nitrogen or phosphorus fertilizer November 15 through March 1; professionals must finish by December 1 and wait until March 1. No fertilizer within 25 feet of a water body — 10 feet with a drop spreader, deflector-equipped rotary spreader, or targeted liquid. Professional applicators must be certified through Rutgers, and lawn fertilizer sold in-state must meet slow-release nitrogen standards. Plain-language summaries: Jersey-Friendly Yards and the Ocean County Soil Conservation District. Under Sod™ also maintains a New Jersey guide to what can legally go beneath new sod here.
• Massachusetts — 330 CMR 31.00 (turf provisions effective June 5, 2015, under Chapter 262 of the Acts of 2012) allows phosphorus-containing fertilizer — above 0.67% phosphate, excluding organic compost and natural organic fertilizer — only when establishing a new lawn or renovating an existing one, or when a UMass-method soil test within three years shows a need. No phosphorus fertilizer December 1 through March 1, and no plant nutrients on frozen, snow-covered, saturated, or frequently flooded soils. Buffers: 20 feet from surface waters broadcast, 10 feet with precision equipment, and 100 feet from surface waters used for public drinking supplies (full regulation text; MDAR factsheet). Several Cape Cod, Martha's Vineyard, and Nantucket towns layer stricter local rules on top.
• Rhode Island — The regional outlier: the NEIWPCC regional summaries list no statewide phosphorus application ban comparable to RI's neighbors. University of Rhode Island Extension guidance still calls for phosphorus-free fertilizer on established lawns unless a soil test shows a need. Confirm current RI DEM guidance and local ordinances.
• New Hampshire — Two layers. The turf fertilizer law (RSA 431, effective January 1, 2014, tightened effective 2025) restricts phosphate in retail turf fertilizer for established lawns, and caps even the products intended for new or repaired lawns at labeled rates of 0.25 pounds of phosphate per 1,000 square feet per application and 0.5 pounds per year — the only per-application starter cap in the region. Annual nitrogen is capped at 3.25 pounds per 1,000 square feet. Golf courses, parks, athletic fields, and sod farms are exempt (UNH Extension factsheet). Separately, the Shoreland Water Quality Protection Act (RSA 483-B:9) bans all fertilizer except limestone within 25 feet of the reference line of public waters, and from 25 to 50 feet permits only low-phosphate, slow-release nitrogen products (NH DES FAQ). Under Sod™'s New Hampshire guide covers working within the per-application caps.
• Vermont — Act 37 of 2011, codified at 10 V.S.A. § 1266b and effective January 1, 2012, is stricter than the "standard" template in three ways. The establishment exception only covers products labeled as starter fertilizer, applied when first establishing grass via seed or sod, limited to the first growing season — a generic high-phosphorus fertilizer does not qualify. The soil-test route requires a test within 18 months. And no fertilizer of any kind may be applied to turf October 15 through April 1, the earliest cutoff in the region, with a 25-foot buffer from waters of the State. Turf fertilizer must also meet a slow-release nitrogen standard (Vermont Agency of Agriculture). Because only starter-labeled products qualify, Under Sod™'s Vermont guide to fertilizer under new sod is worth reading before install day.
• Maine — Maine regulates the shelf, not the spreader: under 38 M.R.S. § 419 (since January 1, 2008), retailers may not sell fertilizer above 0.67% phosphate without a Maine DEP-approved sign stating it isn't appropriate for lawns or turf — except when a soil test shows a need, or for establishing a new lawn or turf, including at a sod farm, or for reseeding and overseeding (Maine DEP). Some municipalities, such as South Portland, add much stricter local ordinances.
• Pennsylvania — A recent statewide law prohibits phosphorus in turf fertilizer except for organic products, products labeled as starter fertilizer, or turf repair. It also limits nitrogen and requires slow-release nitrogen to meet an enhanced-efficiency standard.

Northeast quick reference

Midwest

• Minnesota — The first state in the nation to regulate lawn phosphorus (phased in 2004–2005). Phosphorus is allowed only with a soil test showing need or for new turf establishment; the law cut phosphorus in lawn fertilizers roughly in half within a few years.
• Wisconsin — Statewide turf phosphorus restriction with the standard soil-test and new-establishment exemptions.
• Michigan — Public Act 299 (effective 2012) bars phosphorus on residential and commercial lawns unless a soil test, new establishment, or another exemption applies; includes a 15-foot setback from surface water and preempts most local ordinances.
• Illinois — Statewide restriction; notably, phosphorus turf fertilizer may generally be applied only by licensed lawn-care professionals.

Mid-Atlantic

• Maryland — The statewide Lawn Fertilizer Law supersedes local ordinances, limits nutrient amounts, and restricts phosphorus content; homeowners are held to the same standard as professionals, as part of Chesapeake Bay protection.
• Delaware — The Delaware Nutrient Management Law (3 Del. C. §2250) prohibits phosphorus on turfgrass unless a soil test recommends it, or it's used to establish, re-establish, or repair turf.
• Virginia — Statewide restrictions on phosphorus lawn fertilizer, with the standard soil-test and new-lawn exemptions.

West

• Washington — A statewide restriction limits phosphorus in turf fertilizer to curb runoff into the state's waters, with the usual exemptions for soil-tested need and new establishment.

Florida (local, not statewide)

• Florida — No single statewide ban. Instead, many counties and cities adopt a state model ordinance, often prohibiting fertilizer containing nitrogen or phosphorus during the summer rainy-season "blackout" period, with soil-test requirements in some counties and buffer zones near water. Rules differ sharply by jurisdiction.

This list isn't exhaustive. Other states and a great many counties and towns have their own restrictions, buffer rules, and blackout dates. The pattern is national and still spreading — so the safe assumption anywhere is low-phosphorus unless a soil test says otherwise, and a quick check of your local ordinance.

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How to stay compliant (and not waste money)

• Read the bag. Middle number is phosphorus. Buy a "0" or a low middle number unless a test tells you otherwise.
• Soil-test before you apply phosphorus. In many states a soil test is the legal basis for applying phosphorus to an established lawn — and it's the smart move regardless. A standard test runs roughly $10–$20 through most state university labs.
• Use low or no phosphorus plus slow-release nitrogen. This is compliant in essentially every jurisdiction and is what most lawns actually need.
• Mind setbacks and blackout dates. Don't apply near water or on frozen, saturated, or paved surfaces, and check your state's seasonal restrictions.
• For new sod specifically: you're generally exempt and may use phosphorus — but test first, because most established-soil installs don't need it.

That low-phosphorus, soil-test-first approach is exactly what Under Sod™ is built around: a 4-2-5 with mycorrhizae, humic acid, and seaweed extract, formulated for the soil-to-root zone beneath new sod. Its low phosphorus keeps you compliant for the install and for every feeding after — and where a soil test shows you genuinely need more phosphorus, that's the case the new-establishment exemptions were written for.

Bottom line

Across at least 16 states, the law has reached the same verdict as the soil science: phosphorus on an established lawn is the exception, allowed mainly when a soil test proves a need — and new sod is the carved-out window where it's broadly permitted. Use that window wisely. Test your soil, default to low phosphorus, and you'll satisfy the agronomy, the law, and the watershed all at once.

Related reading

• The Truth About Phosphorus and New Sod — why the high-phosphorus reflex is usually wrong, and what the research and state soil labs say.
• The Best Fertilizer to Put Under New Sod — An Honest Comparison — Under Sod, starters, Milorganite, compost, and 10-10-10 side by side.
• Fertilizer Mistakes That Kill New Sod — the eight feeding mistakes that do the damage, and the fixes.
• Under Sod™ — fertilizer built for beneath new sod — specification and application rate.