Thursday is the deadline for landscape professionals in North Port, Fla., to become certified in water friendly fertilizer use.
The city's fertilizer restrictions came late last year as part of a regional push, led by Sarasota County, to fight pollution and possibly red tide caused by runoff.
North Port's law forbids turf fertilization during the rainy season, June 1 through Sept. 30.
The city is offering a grace period until June 11.
"During this time, we're not giving fines," said Elizabeth Wong, North Port's storm-water manager. "We're just telling them to get up to speed."
After the grace period, violators face fines of up to $500.
Last month, the city sent out about 160 letters to landscaping companies and gardening suppliers informing them of the new restrictions.
North Port and Sarasota County are relying on the voluntary diligence of tens of thousands of residents and home gardeners to use the right fertilizers and, during the rainy season, use none at all, since no money is set aside to enforce the new laws.
Commercial users can receive their certification through the local University of Florida extension, taking a five-hour class. They must be certified by Thursday.
North Port has already certified its own landscaping staff.
"Whatever they learned, they are going to be implementing," said Sherry Borgsdorf, the city's general services director.
The North Port and Sarasota County laws are similar but not identical. North Port allows rainy season use of fertilizers on landscape plants, while Sarasota County forbids it. And, while Sarasota County permits fertilization on the slope of some riverbanks, North Port forbids any fertilization on the banks of a pond or waterway.
The differing fertilizer laws between municipalities have drawn criticism from industry professionals and growers groups, who call for a more uniform approach to regulating fertilizer use.