In much of our area, soils are naturally high in phosphorus so lawns generally don’t
need extra phosphorus. Our lakes are also high in phosphorus which promotes weed and algae growth. If you water your yard from the lake, you are already fertilizing every time you water.
By law since 2005, Minnesota homeowners cannot use fertilizers containing phosphorus,
except for exemptions for new lawns or when a soil test indicates a need for phosphorus. The law did not prohibit retailers from selling phosphorus fertilizers. When shopping for fertilizer, buy a brand that has a middle number of zero i.e. 22-0-15.
If you need to fertilize, here's some precautions to take:
Eliminate the use of fertilizers near water or wetlands.
Before you consider fertilizing your lawn, aerate it first and see if that improves its health.
Use the minimum amount needed to replenish the soil and apply at the right time of year. Late summer and early fall are the best times of year to fertilize your garden and lawn. Early spring applications of fertilizer can make your lawn look nice from the surge of top growth, but it ultimately depletes the plants' energy reserves.
Sweep fertilizer that has spilled on hard surfaces back onto the lawn to prevent runoff.
Water-in fertilizers following application for maximum effectiveness, to reduce runoff, and to reduce the chance of damaging the lawn (i.e. fertilizer burn).
Weed-and-feed products are not recommended as they often compromise the effectiveness of the fertilizer, herbicide or both during application.