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Homeowners Lawn Care Water Quality Almanac

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June           How does your grass grow?

Focus on fall fertilizing!

Prepare for summer stress
Growth of a Grass Plant

  • Cool-season grass plants do most of their growing in the spring and fall. Substantial root and leaf growth occurs in the spring. 

  • Fertilizers applied in early spring will accelerate shoot growth at the expense of root growth. This lush, succulent growth makes the plant more susceptible to diseases and insects and requires more frequent mowing. 

  • Early spring seeding and fertilization can benefit lawns that are thin or bare from winter injury. 

  • Roots grow well in late summer and fall when temperatures cool and the plant can store carbohydrates (energy) from photosynthesis so the plant has an adequate food supply to enable spring recovery. 

  • The ideal time to fertilize is two weeks after your last mowing. Use a fertilizer that is about 70 percent slow-release nitrogen (IBDU) and 30 percent water-soluble nitrogen. The application should supply 1 lb. N/1,000 ft.2

Protect water quality by
  • using proper irrigation and fertilization practices.
  • providing the correct amount of water and nutrients. This will help produce a dense mat of turf that will filter pollutants before they enter the groundwater, thus reducing surface water runoff and erosion.



Know the 

soil infiltration rate: Insert a coffee can with the ends cut off into the soil and pour in approximately 1 inch of water. Note how long it takes to infiltrate the surface.

irrigation rate: Place a can on an area that is being irrigated and note the amount of water in the can after 15 minutes. This tells you how much water you are applying.
amount of precipitation: Leave a can in your yard to measure weekly amounts of 

precipitation. To avoid runoff, precipitation or irrigation should not exceed soil infiltration.

lawn’s water needs: Healthy, actively growing turfgrass requires about 1 inch of water a week (by rain and/or irrigation).

best time to water: Water in the early morning to reduce evaporation and so plants dry by mid-morning. Prolonged leaf wetness can lead to disease.

Fertilizers and Water Quality
Fertilizer Type  Advantages  Disadvantages  Potential to Affect 
Water Quality 
Slow release/   
More constant supply of nitrogen with low burn potential More expensive Low
Quick release  Less expensive  Water soluble; has 
rapid response and
higher burn potential

Fall is the best time to fertilize your lawn
1 lb. N/1,000 ft.2 on Memorial Day/first week of June
1 lb. N/1,000 ft.2 on Labor Day
1 lb. N/1,000 ft.2 on Thanksgiving (two weeks after last mowing)

June is a good time for

  • Mowing: Keep your lawn 3 inches tall to reduce stress and pest problems from mowing too short. However, studies have shown that mowing at the low end of the species tolerance on irrigated sites can reduce water use.
  • Fertilizing: Apply 1 lb. N/1,000 ft.2
  • Irrigating: Begin to water an area that you want to remain green all summer if your weekly rainfall is less than 1 inch. To prevent runoff, your precipitation or irrigation rate should not exceed your infiltration rate.
  • Scouting: Walk your property (scout) in the early morning to help detect problems in the early stages when control methods are most effective.

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This page last updated on
November 05, 2000

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