As of January 1, 2025, new restrictions on turf fertilizer use are in effect across New Hampshire. These updates, introduced through House Bill 1293, were initially vetoed by Governor Sununu but later enacted after a legislative override.

These changes strengthen earlier regulations under RSA 431:4-a–d, which have been in place since 2013. The 2025 revisions come with some significant new restrictions which apply to both commercial users and homeowners.
The updated laws aim to provide stronger protections for the state’s waters by reducing the amount of nutrients carried to our waters through runoff. While both nitrogen and phosphorus contribute to fueling algae blooms, the new regulations specifically target phosphorus, as this nutrient is a key driver of the increased frequency and severity of harmful cyanobacteria blooms seen in the state in recent years.

Understanding the new regulations will help you stay compliant, protect local ecosystems, and build trust with your clients.

As of 2025, you may not apply turf fertilizer in the following situations.
Within 25 feet of:

• a storm drain or any area where runoff could enter a storm drain.
• any surface water, artificial or natural, no matter the size. This includes all rivers, streams, creeks, brooks, reservoirs, ponds, lakes, springs, etc.

During the following conditions:

• heavy rainfall or when heavy rainfall is predicted.
• when the ground is frozen.
• when the grass is dormant (not actively growing).
• on impervious surfaces (like driveways, sidewalks, or patios)
  Tip: Mark buffer zones around storm drains and surface waters on client properties. Carry brooms or blowers to clean up hard surfaces immediately after applying.

Updated rules on nutrient application rates:

• •Only fertilizers that are approved as turf fertilizers may be used on urban turf and lawns. This applies to all turf/lawns in the state except golf courses, parks, sod farms, and athletic fields.
• Turf fertilizer used on established turf/lawns must be no-phosphate or low-phosphate, containing no more than 0.5% available phosphate (down from 0.67% previously allowed).
• Phosphorus application for new lawns or those testing deficient in phosphorus may not exceed 0.25 pounds P2O5 per 1,000 square feet per application and no more than 0.5 pounds per 1,000 square feet per year (down from 1 pound P2O5 per 1,000 square feet annually as previously allowed).
• Phosphorus application rates for natural organic turf fertilizers remain unchanged, with 1 pound available phosphate allowed per 1,000 square feet per application allowed.
• Limits to the amounts of nitrogen that can be applied remain the same, but the wording of the law has been changed to remove what some saw as a potential loophole in the previous version. The phrase, “when applied according to the instructions on the label” has been removed.
  Tip: Review your fertilizer products and adjust rates accordingly. Do not rely on product instructions for application rates.

This is an opportunity to educate your customers and to demonstrate your expertise and commitment to environmentally sound lawn care. Train your crews to effectively answer client questions.

Save the date for UNH Extension’s Landscaping for Water Quality certification program, March 25 & 26, 2026 in the seacoast region. Contact amy.papineau@unh.edu for more information.

~ by Amy Papineau, UNH Extension