Guidelines for fertilizing
By Mike Scott
Lush, green lawn may be a point of pride for many lakefront homeowners, but the fertilizer used to achieve it can have unintended consequences.
Before homeowners decide on the use of fertilizer for their lawn, trees or plants, light research can help determine if, and what type of fertilizer might be best. While the right decisions can help a yard look as vibrant as desired, poor decisions can have even more serious ecological consequences that hurt a lake’s ecosystem.
The state of Michigan has become more active in outlining fertilizer usage and guidelines over the last two decades. The Michigan legislature approved Public Act 299 in 2010, a measure aimed at reducing phosphorus runoff into lakes, streams and rivers across the state. The law prohibits the use of phosphorus-containing fertilizer on established residential and commercial turf, including home lawns, parks, athletic fields and more, unless specific exemptions apply. Farmers who use fertilizer for agricultural purposes and golf courses are exempt from the law.
Under PA 299, phosphorus fertilizer may only be used if a soil test conducted within the previous three years shows a phosphorus deficiency or if the fertilizer is being applied to establish new grass from seed or sod during its first growing season. Some organic materials, including composted manure and biosolids, are also exempt under limited application rates.
The legislation additionally prohibits fertilizer applications on frozen or water-saturated ground and requires homeowners and lawn care contractors to promptly clean up any fertilizer that lands on sidewalks, driveways or streets where it could wash into storm drains.
It has influenced the fertilizer products that are commercially available around the state, said Progressive Companies Water Resources Leader Paul Hausler. Most fertilizers for established grass products available at local retailers targeting consumers have zero phosphorus in the bags. However, it is unlikely the average homeowner will get caught. Today, many fertilizer products marketed to homeowners prominently feature a "middle number" of zero in their nitrogen-phosphorus-potassium (N-P-K) ratio, reflecting the shift toward phosphorus-free lawn care across Michigan.
“The caveat is that it is not strictly enforced,” Hausler said. “There’s no way to do it. So, it serves as a voluntary law.”
Phosphorus is available in starter fertilizer products because of its importance in establishing root product, Hausler said. “It’s only allowed for fertilizers designed for new seed and grass.”
Excess phosphorus can be harmful to a local inland lake environment. Phosphorus is a nutrient commonly found in fertilizers that can wash off lawns, driveways and streets during rainstorms and eventually make its way into nearby waterways, according to Michigan State University Extension. While phosphorus helps plants and grass grow, even small amounts entering freshwater lakes can create significant problems beneath the surface.
Phosphorus, along with other runoff items like road salt for winter’s ice roads, can get stuck at the bottom of a lake, making it difficult to find or remove, said Melissa DeSimone, executive director of the Michigan Lakes and Streams Association.
Phosphorus in a lake is also food source for algae and aquatic weeds. That in turn fuels algal bloom growth. Hausler said. As algae die and decompose, the process consumes oxygen in the water, which can arm aquatic life from fish to plants. Some blue-green algae blooms can even produce toxins that may pose risks to people and pets that encounter affected water.
“The amount of phosphorus can dictate algae growth,” Hausler said. “(A lake) gets most of its nutrients from sediments. Studies from Michigan State University and elsewhere have shown that some lakeshore sediments collected from Michigan lakes are already high in phosphorus, Hausler added.
Environmental agencies, including the U.S. Environmental Protection Agency (EPA) and Michigan's Department of Environment, Great Lakes, and Energy (EGLE), have identified reducing phosphorus runoff as one of the most effective ways communities can protect water quality and limit harmful algal blooms. Such runoff can leach into lakes and create “dead zones” where it is difficult or impossible for plant or aquatic life to thrive. These dead zones are caused by algal blooms that deplete oxygen levels.
“It’s hard for (life) to grow when you have harmful (runoff),” DeSimone said.
Nitrogen is another element that can be damaging to a waterbody. Excess nitrogen from lawn fertilizer, agricultural runoff, septic systems and stormwater can contribute to algae growth, reduce water quality and, in some cases, promote harmful algal blooms similar to those associated with phosphorus pollution.
Phosphorus is typically considered the more significant concern because it considered as a “limiting nutrient.” In other words, it is in the shortest supply and therefore has more control over algae growth, Hausler said. Many Michigan lakes naturally contain adequate amounts of nitrogen but relatively low levels of phosphorus.
Excessive nitrogen fertilizer applications can still contribute to runoff pollution, contaminating groundwater with nitrates, Hausler said. It can encourage unnecessary turf growth that requires more mowing and irrigation. Ammonia is a type of nitrogen that can be effectively used to eliminate algae, he added.
Furthermore, Earth’s atmosphere is made up of about 78 percent nitrogen. Lightning increases the amount of bioavailable nitrogen in the environment because it provides enough energy to break apart one of the strongest chemical bonds in nature. Lightning superheats the air to temperatures of about 30,000 degrees, new compounds form and rain delivers nitrogen to the soil.
“The fact that (nitrogen) is everywhere impacts its role in the environment,” Hausler said. “That’s why phosphorus has received more attention) from the state. You will always have access to nitrogen.”
Homeowners can use a slow releasing nitrogen fertilizer as well, which can be identified by reading the bag or researching brands ahead of time, said Shannon Ervin, stormwater coordinator for the Clinton River Watershed Council.
There are typically three options for homeowners to have their lawn or trees fertilized. One is to do it themselves, which can save money but can be ineffective if not managed properly. Hausler said that significant research is needed to ensure the proper fertilizers and amounts are used.
The second is to contract a lawn or gardening service. In that case, homeowners will want to question what type of fertilizers are being used, and the effectiveness of each recommended spray. Ervin said that the Michigan Green Industry Association (MGIA) has a certification process that allows providers to become a landscape industry exterior technical professional through the National Association of Landscape Professionals. Those interested can learn more at the MGIA’s website at landscape.org.
Hausler said that some contractors may suggest more sprays than is needed to effectively kill harmful weeds for lawn or trees. One way to determine the best type of fertilizer treatment is to have your soil tested by an expert like Michigan State University Extension.
For Michigan homeowners, the MSU Extension home lawn and garden soil test mailer costs $26 per sample. That price includes the testing, a prepaid mailer to send a soil sample to the laboratory, and a personalized report with fertilizer and soil amendment recommendations tailored to a homeowner’s lawn or garden. Results are typically available within about 10–14 business days after the lab receives your sample.
Test results can help to establish a strategy based on how the lawn is used, how much shade it gets, and more. For example, families that have young children who frequently play on a portion of their lawn may use a different approach for fertilization, especially after discovering the soil results. Learn more by visiting the MSU Soil Test webpage at homesoiltest.msu.edu.
“However, you have your (property) fertilized, getting your soil tested is a great step to be sure that you are educated,” Hausler said. “If you do contract to a third party, you can show them your soil results, and there may be an opportunity to adjust the treatment schedule. You may want to (test your soil) before hiring a service professional.”
Another fertilizing option is to irrigate directly from a body of water if the property borders on one. That can be one of the best options because nutrients that can kill weeds are already present in the water. It still takes research and the right equipment, not to mention a plan to cover the entire area of focus.
The most natural type of fertilizer is compost, Ervin said. If a soil test determines fertilizer is beneficial, compost can be particularly effective for native plants or grass with longer roots than turfgrass. It is best applied in the early fall and late spring, so that it will positively impact deep parts of the soil, she added.
“It can also be a cheaper alternative than many types of fertilizer,” Ervin said. “You want to spread it around just as you would a fertilizer you buy at the store.”
Many retail stores sell bagged compost, but dead leaves gathered from the ground can be just as effective. Ervin said homeowners want to use the right amount of compost, especially leaves, because if too much is spread on the soil it can choke out the grass.
“Make sure that you use a lawn mower to cut the compost into pieces so that it gets into the soil and doesn’t shade out the grass,” Ervin said. “Spreading (compost) is key. It is also a good option for native insects.”
Homeowners can choose not to use any fertilizer. “That may not be the best option based on your lawn, but when in doubt, you do want to lean toward using (less fertilizer or treatments) if you can,” Hausler said. “People like their green lawns.”
Yet fertilizer may not even be necessary at all, DeSimone said. She said properties that border lakes likely have soil already rich in nutrients and that adding fertilizer may not help. She also suggests getting a soil sample to learn more.
“The outcome for many (households living on or very close to a lake) may be acceptable without fertilizer, even if you want that nice, green lawn,” DeSimone said. “You don’t want to add fertilizer unless there’s really a need.”
Another way to limit the adverse impact of fertilizer is to consider non-traditional types of grasses instead of Kentucky bluegrass or other types of turfgrasses. One example is to plant a fine fescue, which can closely resemble the look of a turfgrass with less potential for obvious weed growth, DeSimone said. Fescues require less watering, less or no fertilizer, grow well in Michigan and are excellent for partially shaded lots by a lake. An added benefit is that Canadian geese don’t seem to like eating fescue.
“We’ve used fescue in our lawn (at home), and we haven’t needed fertilizer and mow less than is needed with (turfgrass),” DeSimone said.
It is also important to understand that what most homeowners refer to as weeds are actually native plants that are used to growing in the area. Such plants or weeds may choke healthier-looking grass, but that is more obvious with turfgrass varieties. Common dandelions for example are considered to be “naturalized” rather than invasive today, since they were introduced to the area in the 1600s, according to MSU Extension. Other so-called weeds are actually native.
“Many of these ‘weeds’ are native and want to grow here,” DeSimone said.
She admits that hand-sprayed weed killers, which aren’t technical fertilizers, but pesticides designed to be part of the common group the residential of lawn and garden products available to consumers, can be useful in small, concentrated areas. But they should also be used judiciously.
Regardless of the type of fertilizer or compost used, homeowners should always sweep up any excess material afterward to help prevent runoff from stormwater
A healthy lawn has long been synonymous with regular fertilizer applications for many homeowners. But Oakland County Water Resources says that a greener landscape requires effective lawn care practices as much or more than fertilizer. In fact, many southeast Michigan soils already contain sufficient phosphorus to support healthy turf, making routine fertilizer applications unnecessary.
A healthy lawn also begins with healthy soil. Rather than relying solely on synthetic fertilizers, Oakland County Water Resources encourages homeowners to build soil naturally by applying compost, shredded leaves or wood-chip mulch around trees and garden beds.
Organic mulch helps retain moisture, reduces evaporation during the heat of summer, suppresses weeds and gradually returns nutrients to the soil as it decomposes. A diverse landscaping plan can incorporate native flowers, grasses and shrubs, according the OCWR website and flyers. Such a plan not only creates visual interest but also attracts beneficial insects that naturally help control pests, reducing the need for chemical treatments.
Additionally, deep-rooted native plants improve soil structure and increase the ground's ability to absorb rainfall, helping keep both sediment and nutrients out of local waterways.
Lawn care and lake care are closely connected, especially for those with direct access to the lake from their property. Decisions like testing soil before fertilizing and improving soil health with compost and planting native vegetation can reduce stormwater runoff while creating landscapes that are naturally more resilient.
As Trisha Bruzek, communications officer for Oakland County Water Resources, confirmed, the county's educational resources at oakgov.com/government/water-resources-commissioner are designed to show residents that maintaining an attractive yard and protecting Oakland County's lakes are not competing goals.
Homeowners can utilize one or more types of green infrastructure to create a barrier between their lawn and the shoreline if they directly border a lake. The intent is forcing runoff to go away from the water and produce the least amount of infiltration. Runoff can carry any harmful substance in its path from pesticides to pet waste to oil and gas residue. Pest waste in particular can be responsible for high levels of E.coli, a type of bacteria that normally lives in the intestines of humans and animals and can cause stomach issues.
Lakefront homeowners can also get more information about the impact of lake runoff by getting portions of the lake tested for various substances.
“When you create a buffer zone it is all about balance,” DeSimone said. “I know many homeowners may want to use their yard for other activities, including for their children to play. But fertilizer can have the greatest amount of (adverse) impact water quality of any potential runoff substance.”
Ervin recommends homeowners have at least a 20-foot buffer area between the water’s edge and grass. The buffer ideally should include native plants that are taller than the grass it borders.
Unlike many traditional lawn grasses, Michigan native plants develop deep, extensive root systems that help rainwater infiltrate the soil while stabilizing slopes and reducing erosion. Around shorelines and property edges, native vegetation acts as a living buffer that captures sediment and excess nutrients—including fertilizer—before they enter the water. Some of the most common types of native plants that are a part of many buffers are Black-eyed Susans and Purple coneflowers, she added.
“It is also a good buffer for geese, which you ideally want to avoid,” Ervin said. “Having that much of a buffer is a good way to filter out stormwater and any fertilizer runoff.”
Green infrastructure examples along the shoreline can include rain gardens, bioswales and daylighting pipes. These serve as “filter strips” which act as that barrier with the lake. A filter strip is often at least six feet wide. It can also include natural or ornamental grass. Hausler recommends just about anything with deep roots that can be part of a lakeshore filter strip. Turf grass is a poor filter strip since it has very short roots and therefore would be a poor barrier for runoff.
It should be treated as a wetland area and can be a habitat for insects and organisms that thrive near the lakeshore. Hausler said these green infrastructure examples along the shoreline generally should not be fertilized.
“It’s good to have it as an aesthetic habitat,” Hausler said. “You can make it look nice.”
Homeowners that are having construction projects on their property may want to consider having a temporary silt fence that prevents some construction-related runoff from getting into the soil, adding unnecessary nutrients into the water.
Additional information about these strategies can be found at the website for the Michigan National Shoreline Partnership at shorelinepartnership.org. The page has information about fertilizer use, natural shoreline design and landscaping, native plant recommendations, shoreline erosion control and more.
One of the biggest misconceptions among lakefront and near-lake homeowners is that protecting water quality begins at the shoreline. In reality, it often starts much farther uphill, such as on the driveway, on the lawn, or wherever rainwater leaves a property. Rain gardens can connect a roof through downspouts and hold water for 48 hours before it is distributed, further reducing fertilizer runoff.
It can take some work to build and manage a rain garden, but it is often less laborious than most homeowners realize. Building one starts with removing the top three to six inches of soil, which can be done using a sod cutter.
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There is math that needs to go into a rain garden,” Ervin said. “It is an engineered process.” Ervin said that a rain garden should be placed at least 10 feet from the house and five feet from the edge of a property line.
The Clinton River Watershed Council sells a limited number of 55-gallon rain barrels each year, any of which can be designed, painted and prepared in a way that fits in with the property’s surroundings. Rain barrels collect roof runoff during rainstorms and homeowners can reuse that water later to irrigate gardens and landscape beds. That reduces both stormwater runoff and demand on municipal water supplies.
Oakland County has a Rain Start Program that reimburses residents up to $2,000 in a calendar year for installation of one rain garden, a maximum of two water rain barrels and the planting of two trees during the same year. The county will send a representative to a home to help the property owners qualify for the program and strategize where the items can be placed.
Oakland County Water Resources reminds residents that stormwater runoff is one of the primary ways pollutants, including excess fertilizer, make their way into lakes, streams and wetlands. As rain falls on rooftops, sidewalks, patios and driveways, it cannot soak into these hard surfaces. Instead, the water flows across the landscape, collecting grass clippings, pet waste, soil, fertilizer and more before carrying those pollutants into nearby waterways.
The consequences can be significant. Nutrient-rich runoff fuels excessive aquatic plant growth and harmful algae blooms, reduces water clarity, contributes to shoreline erosion and degrades fish and wildlife habitat. Even neighborhoods that aren't directly on a lake are connected through storm drains and creeks that eventually discharge into Oakland County's interconnected watershed.
Fortunately, homeowners have more influence than they may realize.
Water runoff from impervious surfaces like sidewalks and driveways can have an outside impact on where rainwater ends up. In short, rainwater and runoff that flows from a hard surface generally flows directly into groundwater and then into a river, untreated.
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You want to be aware of that and be very careful with how your construct or (change) a hard surface around your home,” DeSimone said. “That is where rain gardens and rain (barrels) can be very effective. Rainwater or runoff on hard surfaces doesn’t have any soil to go through so it heads right to the (groundwater).”
Oakland County Water Resources encourages residents to think of their property as part of the natural filtration system rather than simply a place to shed water as quickly as possible. One of the most effective improvements is installing a rain garden—a shallow landscaped area planted with native vegetation that captures runoff from rooftops or downspouts. Instead of rushing untreated into the storm sewer, rainwater is temporarily stored, allowing it to slowly soak into the ground where soils and plant roots naturally filter pollutants before they reach lakes and streams.
Even the choice of landscaping materials matters. Replacing portions of traditional concrete or asphalt with permeable pavers, gravel, mulch or other porous surfaces allows rainfall to soak into the ground instead of immediately running off the property.
These simple changes become even more important when homeowners fertilize their lawns. No matter how carefully fertilizer is applied, heavy rainfall can wash unused nutrients into nearby lakes if runoff isn't managed. That's why Oakland County Water Resources emphasizes that healthy lawn care and effective stormwater management go hand in hand.
Bruzek says Oakland County's educational resources are designed to help residents understand that every property, even those miles from a lakefront, play a role in protecting Oakland County's treasured lakes.
The discussion around fertilizer use should consider the expectations that homeowners have. DeSimone said it is unrealistic for homeowners to expect to have “golf-course quality lawn” if they also want to be environmentally sensitive to what’s best for the local water table and waterbodies.
“There’s a perception that you can have a golf course grade lawn but the fertilizer you use will still runoff into a storm drain untreated into a local river,” DeSimone said.
One way to determine where a lawn’s water, and therefore runoff goes, is to visit the River Rubber website at river-runner.samlearner.com. There, homeowners can open an interactive map created by data visualization developer Sam Learner that simulates the path a single raindrop that falls within U.S.-based neighborhoods take as it flows downhill through streams, rivers, and watersheds until it reaches a lake or the ocean. It uses elevation and U.S. Geological Survey hydrology data to trace the downstream flow path.
You want to do whatever you can to promote infiltration and decrease runoff,” Hausler said.
Many residential homeowners also have certain tree fertilized to prevent fungi such as oak wilt, anthracnose and tar spot. Hausler recommends that homeowners keep trees several feet, at least, away from the water, to help prevent fertilizer from getting into the water system, especially during in autumn, can also build up in a lake, creating the potential for extra muck and unwanted infiltration.
“You always want to err on the side of less is more,” Hausler said.
Michigan has some of the nation's stricter regulations governing lawn fertilizer use, largely because of concerns over phosphorus runoff into inland lakes, streams and the Great Lakes. In addition to the phosphorus restrictions on established lawn from PA 299, commercial fertilizer manufacturers, distributors and applicators have been regulated through licensing, registration and reporting requirements administered by the Michigan Department of Agriculture and Rural Development.
Michigan law also prohibits fertilizer application on frozen or water-saturated ground and requires that any fertilizer spilled onto hard surfaces such as sidewalks, driveways or streets be immediately cleaned up to prevent stormwater transport into waterways, according to the EGLE website. The regulations “reflect Michigan's emphasis on protecting water quality while still allowing responsible nutrient management for lawns, landscapes and recreational turf,” the website states.
Several Oakland County lake communities have adopted local fertilizer ordinances as well, in part because local officials were seeing algae growth and declining water quality in their inland lakes.
Commerce Township, for example, ties fertilizer regulation to lake protection. The township prohibits the application of fertilizers containing phosphorus on turf and places limits on annual nitrogen applications. The ordinance applies to homeowners, renters, commercial applicators and institutional users alike.
Commerce Township also prohibits fertilizer applications when the ground is frozen, between November 15 and April 1, or when rainfall is expected that could create runoff conditions. Importantly for lakefront property owners, annual nitrogen applications are limited to four pounds per 1,000 square feet for lakefront properties, compared with five pounds elsewhere in the township. The local ordinance was originally adopted in 2003, making it one of the earlier municipal responses to nutrient runoff in southeast Michigan.
West Bloomfield Township and Bloomfield Township have ordinances targeting commercial entities. West Bloomfield requires registration and licensure for commercial and institutional fertilizer applicators operating within the township and explicitly recognizes the connection between over-fertilization and nutrient loading into lakes, wetlands and watercourses.
Bloomfield Township adopted fertilizer regulations in 2010 that require registration of commercial applicators while establishing local application guidelines designed to protect lakes, streams, wetlands and drains. One provision includes a 25-foot fertilizer setback from lakes, streams, wetlands, drains and other watercourses, meaning fertilizer cannot be applied within that buffer area unless an exception is granted through soil testing or administrative review.
Other local ordinances directly or indirectly impact fertilizer use in such communities as Orion Township, Oxford Township , Independence Township , White Lake Township, Highland Township and more.
Many of these communities participate in watershed protection initiatives through the Oakland County Water Resources department.
For lakefront homeowners, protecting water quality doesn't require sacrificing a beautiful landscape. Instead, it requires making informed choices that support the local ecosystem and water sources. From testing soil before applying fertilizer and planting native vegetation to creating shoreline buffers and reducing stormwater runoff, even small changes can have a lasting impact.
As DeSimone said, every property in a watershed is connected, and every homeowner plays a role in keeping local lakes cleaner, healthier and more resilient for all use
“What we do matters a lot,” DeSimone said. “Much of it comes down to knowing how and when to best use (fertilizer).”
