Connecticut residents who maintain lawns in the state may not be aware of the new legislation which would regulate phosphorus fertilizer applications to established lawns. In May of 2012, the Connecticut legislature passed a Senate bill, SB 440, which addresses phosphorus in fertilizers. It is scheduled to go into effect starting January 1, 2013. This bill would ‘limit the use of phosphorus in lawn fertilizers and add phosphorus clean-up to the qualifying criteria for the Clean Water Fund.’ Several other states, including New Jersey, have already implemented similar regulations. Why the need for this legislation?

Many folks visit our New England states because they consider them quaint and pristine, and our long-standing environmental regulations have kept them that way. Since phosphorus pollution is the principle cause of declining water quality in Connecticut’s lakes and ponds, and many local economies depend on clean water for tourism, fishing and bait shops, adjacent restaurants and other local stores and venues, this bill will have far-reaching benefits. It is critical to keep our ponds and lakes clean and clear. Improper soil phosphorus management results in algal blooms, fish kills, weedy and uninviting lakes, and even health risks to humans.

Having high levels of phosphorus in the soil will not harm terrestrial plants but it can adversely affect aquatic systems. Phosphorus, whether from fertilizers (organic or synthetic), manures, or faulty septic systems, stimulates the growth of algae and other aquatic plants in fresh water lakes, ponds, and streams. Excessive growth of aquatic plants, but most especially algae, from phosphorus additions to lakes, ponds and streams causes eutrophication of the water bodies. Eutrophication occurs when the algae naturally die and decompose. The organisms that break their bodies down require oxygen to do so and this high demand lowers the oxygen levels in the water body to the extent that many fish and shellfish die. Eutrophic water bodies are not fun places to swim in, and waterside residents are typically upset when lakes and ponds go eutrophic. In general, eutrophication lowers water quality considerably, thereby restricting the use of fresh waters for drinking, recreation, fishing and other aquatic industries. In some states, 80 percent of water bodies are so affected that they are unfit for human recreation.

Eutrophication can also cause serious health risks to both humans and livestock. Algal blooms of cyanobacteria can produce cyanotoxins which are poisonous and sometimes fatal to both man and animals. Consuming shellfish such as clams, mussels, scallops or oysters contaminated with the cyanotoxin can poison humans.  Another organism, a dinoflagellate known as Pfiesteria piscicida, produces a highly toxic chemical that causes neurological damage in humans and has been found in waters in the eastern United States, in particular in the Chesapeake Bay tributaries. Because of all these concerns, eutrophication is considered by the Environmental Protection Agency to be the main problem facing United States surface waters.

Now that the problems of phosphorus pollution have been outlined, let’s look at some of the provisions of the new legislation. First and foremost, the new law would only allow the applications of fertilizers that contain phosphorus on established lawns when a soil test, performed within the last 2 years, recommends additions of this element. While lawns do not require large amounts of phosphorus, typically they need more than native Connecticut soils can offer and may need supplementation during their first few years of establishment. Soil tests can determine the need for phosphorus.

Established lawns do not need much phosphorus


For established lawns, the application of any fertilizer, containing phosphorus, would be prohibited from November 15th to March 15th. This makes sense as plants in Connecticut typically are not in an active growth stage during the winter. The UConn Plant Science and Landscape Architecture Department further recommends no fertilizer applications, of any kind, from October 15th to April 15th – in other words, when plants are not actively growing. Of course, as climate change continues to bring us increasingly earlier springs and later autumns, the University may modify these dates and, gardeners’ sense should prevail – if it is 60 degrees F for consecutive days in March, plants may be starting active growth and perhaps could use nutrients a bit earlier than usual.

New lawns, or those being overseeded, are exempt from this law. It is a firmly entrenched fact that phosphorus is essential for optimal root growth and establishment. When turf grass areas are newly seeded or sodded, or overseeded, a fertilizer (organic or synthetic) containing phosphorus is typically applied as soluble forms of phosphorus have been shown to improve plant establishment. Do note that any soil amendment containing 0.67% of phosphate or less is exempt from this legislation. And, that fertilizers containing phosphorus “…shall not be applied to any portion of lawn that is located 20 feet or less from any brook, stream, river, lake, pond, sound, or any other body of water.” Beginning next year, signs about the phosphorus legislation will be prominently displayed at retail establishments that sell fertilizers to inform the public about the problems from phosphorus pollution and their fertilizer options. Lawn fertilizers containing phosphorus will be segregated from those that do not hopefully making purchasing options clearer. 

Clean water is a precious resource. We all need to do our part to prevent pollution. Wise use of phosphorus fertilizers on lawns is one way homeowners can contribute to cleaner waters. For those interested in soil testing or for any updates on the legislation in CT, visit