To Overseed or Not to Overseed?


To overseed or not to overseed? That is the question. In the Phoenix valley of the sun and other parts of Arizona, we are blessed (or cursed?!) with this decision each year as summer starts to wane.

Recent declared water shortages, restrictions on new lawns, and higher water costs have brought turfgrass in general under scrutiny, and overseeding is part of the conversation. Here are some pros and cons of overseeding to consider in order to make the best decision for your outdoor space.

Cooler temperatures in the coming months will cause our thick, green Bermudagrass lawns to turn into a yellow, crunchy surface during some of our most enjoyable months of outdoor entertaining and recreational activities.  A choice could be made to overseed with ryegrass for a lush, green lawn nearly year-round. While the practice of overseeding typically begins in September or October, the decision whether or not to do it needs to be made well in advance. Planning and preparation make all the difference not just in the overseeding season, but the following spring when the Bermudagrass transitions into its growing season.

Overseeding Pros:

  • Provides attractive green lawns from October thru April, when Bermudagrass is dormant
  • Provides a useful surface for entertaining and recreation during the time of year when residents spend a lot of time outdoors
  • Enhances sports field playing surfaces
  • A green, growing lawn protects the area from erosion and can protect dormant Bermudagrass from damage due to heavy foot traffic or play use
  • No Bermudagrass straw dragged in the house and covering the pets and kids all winter
  • Green growing turf cuts down on dust and creates a desirable microclimate
  • Weed suppression – a thick stand of ryegrass can act as a deterrent to winter weeds taking hold

Overseeding Cons:

  • Overseeding costs – labor, seed, extra water for germination
  • Uses significantly more water than the alternative of dormant Bermudagrass
  • Maintenance expenses – mowing, fertilizing, irrigation management
  • Environmental costs – fossil fuels, air pollution from lawn equipment, fertilizer manufacture
  • Overseeding process can be disruptive – low mowing and watering several times per day during germination, staying off the grass for a couple weeks
  • Stresses existing Bermudagrass which can cause uneven greening during the spring transition

If the decision is made to overseed to enjoy that winter lawn, using these SLM® (Sustainable Landscape Management®) practices is recommended:

  • Only overseed areas that will actually be used and enjoyed
  • Do not scalp – instead, mow low, leaving some of the crown of the Bermudagrass tall enough to protect the germinating ryegrass and save water while reducing dust pollution
  • Reduce mowing during the coldest months to once every other week if possible
  • Mulch clippings as much as possible rather than bagging and sending to the landfill
  • Adjust irrigation often using the ET (evapotranspiration) rate information from AZMET (Arizona Meteorological Network) or a smart controller to reduce water waste
  • Consider rotating some overseeded areas each year, allowing the Bermudagrass to “rest” every 1 – 2 years, which can reinvigorate warm season Bermudagrass lawns
  • Remember that Bermudagrass is alive and needs a good, long and healthy growing season in advance of overseeding