Caring for shoreland lawns and gardens

Surface bodies of water and groundwater are critical areas in the environment. These water sources support many ecosystems and provide drinking water for humans and animals. Lawns and gardens near shorelands must be carefully planned and maintained to prevent contamination of surface waters. Consider leaving or planting native vegetation as an alternative to cultured lawns and landscapes.

Follow the rules for planting near the shore

When establishing a new lawn, you must follow Minnesota shoreland management regulations that prohibit excessive vegetation removal near the shore and on slopes and bluffs. Check with your local zoning authority for specific regulations governing the body of water in question.

Prevent ground and surface water contamination

Existing lawns and gardens must be maintained in a way that prevents the possible contamination of ground and surface waters. Shoreland owners must be aware of potential problems caused by soil erosion and pollution due to chemical amendments and organic yard waste.

Special attention should be paid if the following conditions exist:

• Areas of exposed soil, such as flower beds, vegetable gardens or poorly established vegetation.
• Coarsely textured soil, such as sand or sandy loam.
• The property slopes toward surface water.
• Impervious surfaces, such as sidewalks and driveways.
• Lawn or landscape maintenance close to the surface water.
• Fertilizer, pesticide or soil amendment application.

Prevent soil erosion

Surface waters can be contaminated by soil washed or blown into the water. Eroding soil can cause sediment build-up and carry phosphorus into the water, a potential pollutant.

To avoid erosion:

• Maintain a vigorously growing filter zone of grass, trees and shrubs next to surface waters.
• Minimize areas of exposed soil by maintaining native vegetation or dense turf.
• Preserve ice ridges or construct an earth berm near the shore to minimize runoff. The berm should run parallel to the shore to prevent runoff into surface water.

Avoid using chemical fertilizers

Native vegetation does not require fertilizer. Use caution if applying fertilizers to lawns and adhere to the following guidelines:

• Have your soil tested to determine how much fertilizer is needed and minimize the use of chemical fertilizers.
• Use compost or manure instead of chemical fertilizer. However, these also have the potential to damage water quality if used in excessive amounts.
• If chemical fertilizers are used, select slow-release (water-insoluble) forms.
• Water your lawn after fertilizing, but don't allow excess water to run off into surface waters.
• Sweep up any fertilizer spilled on hard surfaces such as walks and driveways, instead of washing it off.
• Use extra caution when applying fertilizer near surface waters.
  • Don't spread fertilizer within 75 feet of surface waters or wetlands.
  • Use a drop spreader and not a cyclone spreader to minimize the possibility of getting fertilizer directly into the water.
• Never apply fertilizers to frozen ground.
• Leave a natural vegetation filter strip of grass, trees or shrubs next to the shoreline. You can also construct a berm along the shore.

Avoid using chemical pesticides

Consult a professional from the University of Minnesota Extension or Soil and Water Conservation District to determine if the use of a pesticide is justified. The following practices will minimize the potential of contamination from pesticides:

• Properly identify whether the pest is an insect, disease or other problem.
• Determine if there is an economic or aesthetic justification for starting control of the pest.
• Consider control options other than the use of a chemical pesticide. Biological controls and pest-resistant plant varieties are available.
• Use the least toxic and most readily degradable pesticide that will be effective.
• Read the pesticide label carefully and pay special attention to safety precautions and warnings about use near water.
• Do not apply pesticides when it is windy to avoid the possibility of drift.
• When purchasing pesticides, buy only what is needed to control the problem during the current season.
• Waste pesticides should be disposed of properly. Never pour excess pesticides on the ground or into surface waters or sanitary treatment systems.
• Consult with your county solid waste office, the Minnesota Pollution Control Agency, or your sanitary district for proper collection and disposal methods.

Managing turf

Turfgrasses and other perennial grasses serve as important buffers (riparian filter strips) to protect bodies of water from pollution caused by run-off and erosion.

Managing turf near bodies of water requires different practices than typical turf management. Turf located near shorelands can have vastly different soil compositions and nutrient management requirements. Fertilizer applications can help improve how these areas function. Still, care must be taken to protect water sources from leaching and runoff of nutrients such as nitrogen and phosphorus.

Fertilizer management

Improving turfgrass density and quality can help mitigate leaching and runoff near water systems. Soil near surface water often is sandy, making leaching easier.

Although incorrect fertilizer use may lead to water pollution, correctly applying fertilizers containing nutrients such as nitrogen and phosphorus can improve turf growth. Visit fertilizing lawns for more general information. 

Nitrogen fertilizers 

Nitrogen is one of the most essential nutrients for turf growth and lawn quality. As a mobile nutrient, nitrogen can leach easily through soils and should be applied through slow-release and stabilized products. Excess nitrogen in soils can oxidize through a process known as nitrification and create nitrates. Increased nitrate in surface and groundwater supplies can lead to potential health risks when consumed by animals and humans and can cause increased algal growth in lakes and streams. 

Phosphorus fertilizers

Phosphorus fertilization can promote turfgrass root development, but most soils in Minnesota have high phosphorus concentrations and do not need additional phosphorus. Phosphorus is an immobile nutrient and does not leach readily. Most sources of phosphorus pollution occur due to surface runoff of water containing soil, plant residues, or animal wastes or from the misapplication of phosphorus-containing fertilizers.

Applying phosphorus in situations not outlined by the Minnesota Phosphorus Lawn Fertilizer Law is illegal. The law allows the application of phosphorus when soil has been tested, or a new lawn is established by seeding or laying sod.

To protect surface bodies of water and groundwater, best management practices from the Minnesota Department of Agriculture and the UMN Turfgrass Science Program include:

Things to do:

• Conduct a soil test to ensure adequate P and K levels.
  • Nitrogen can not be reliably tested in soil.
  • Most lawns benefit from some supplemental nitrogen fertilizer to maintain density and quality
• Water-in fertilizer immediately after application with 0.5-1.0 inch of rain or irrigation water
• Use a rotary fertilizer spreader with a shield or guard to better direct fertilizer away from non-turf surfaces like sidewalks or water. 
• Use a broom and dustpan to collect and spread fertilizer granules into turf areas if they land on impervious surfaces like driveways, sidewalks, or patios
• Use technologies that reduce leaching:
  • Many coated urea fertilizer products contain nitrogen stabilizers. These stabilizers protect the nitrogen sources from volatilizing into the atmosphere and reduce the likelihood of nitrogen leaching through the soil profile.
  • Use products that contain at least 20% slow-release nitrogen and at most 80% quick-release, or water-soluble nitrogen.  

Things to avoid:

• Do not apply fertilizer within 15 feet of a body of water.
• Do not fertilize if more than 0.75 inches of rainfall is expected in a single event.
• Do not apply more than 1 pound of nitrogen per 1,000 square feet in a single application.
• Do not apply fertilizer to dormant turf.
  • Active growing season: May to mid-October, whenever the lawn needs to be mown.
  • Actively growing plants ensure the highest uptake of nutrients applied.

Mowing

• Mow turfgrasses near bodies of water at the highest recommended height (at least 3.0 inches).
  • Encourages root development to acquire nutrients and stabilize soil.
  • You can mow less frequently when following the “one-third rule” and turf is more drought tolerant.
• Do not dispose of lawn clippings into water or near drainage systems.
  • Clippings can potentially cause nutrient pollution in the water.
  • Clippings contain nutrients that can benefit turf growth.
  • Clippings should always be recycled or mulched back into the turf stand.

Pesticides

For more information on pesticide use on turfgrass, visit Best Management Practices for turfgrass pesticides.

• Always follow the label instructions attached to the container you are using.
  • Use an integrated pest management (IPM) approach to increase effectiveness.
• Weather conditions such as rain and high heat can move pesticides into undesired locations.
  • Increasing droplet size can decrease drift.
• Pesticide application equipment should never be used, cleaned, filled in, or adjacent to surface or groundwater water sources.
• Some pesticides are more soluble than others.
  • Soluble pesticides enter easily into the water system through both leaching and runoff.
  • Avoid soluble pesticide use near bodies of water, permeable soils, and low water tables.
• Pesticides with shorter residual times should be used near bodies of water.
  • Longer residual activity controls pests for longer but also increases the potential of pesticide leaching or runoff.

Managing gardens

Flower and vegetable gardens can add to the quality of life for shoreland owners. Certain precautions must be taken to prevent the possibility of surface water contamination.

Locate gardens properly

• Do not locate gardens on slopes because they can promote accelerated soil erosion and runoff. Dense turf or other vegetation should be established on slopes. Terraced gardens are good alternatives. 
• Do not locate gardens on septic system drainfields or mounds. Exposed soil increases the possibility of septic systems freezing. Drainfields and mounds should be covered with dense turf.
• Minimize the area of exposed soil with intensive growing techniques such as inter-cropping, succession planting and raised beds.

Soil fertility management

Fertilizers can cause ground and surface water contamination. This can be avoided by the following practices:

• Test the soil to determine nutrient needs. Apply only the recommended amounts of nutrients.
• Make split applications of the total amount of nutrients required. This includes side-dressing nitrogen-loving crops, such as sweet corn, vine crops, and cabbage family crops.
• Use organic fertilizers such as well-rotted manures and compost.

Pest management

• Use pesticides only if necessary and if there are no other options for pest control.
• Always read the pesticide label. Pay careful attention to warnings on the potential for surface water contamination.

Vegetable wastes

• Do not dispose of vegetable waste in the water, including corn husks, pea pods or other plant material. Compost these materials instead and apply them to garden soil.

Yard waste disposal

Yard waste should never be allowed to enter the water. Yard waste includes leaves, grass clippings, fruit and vegetable wastes, and woody materials. These materials contain phosphorus and may pollute surface water.

Collect and compost yard waste. Compost provides an excellent material for amending flower and vegetable gardens.