Going from Summer to Winter Turf

Dan has written a number of landscape-related articles for us. Here’s another one, focused on what happens to our grass as we move from summer to winter. Thanks for the info, Dan!
— Ray

A lot of changes are likely to occur in your turf grass, as our environment enters the cool season. Bermuda grass will stop growing at 60°F and will go to sleep and turn brown by 50°F. Overseeding is an optional process which will render a Winter lawn to enjoy and appreciate, but preparation and timing are important to a successful overseed.

If you didn’t know, there are generally two types of turf grass used in our climate: warm season & cool season. Each have months of growth in their preferred (and labeled) season with a period of dormancy or intolerance. For example:

  • Perennial Ryegrass grows well in the cool season and often dies off before the high heat of July. Do not bother with Annual Ryegrass, unless it is intended for a large area where maintenance is of little concern. Perennial Ryegrass produces a superior lawn to Annual Ryegrass, although Annual Ryegrass is less expensive in comparison.
  • Bermudagrass grows well in the warm season and enters dormancy as temperatures drop in the cool season.

To Overseed: 

  • If you are intending on overseeding, August and September are usually key months for planning, checking the irrigation system, selecting and ordering seed and process related materials, and to gradually start transitional practices aiming to drop seed around the last week of October.

Process Summary

  1. 30 days before overseeding
    1. Stop nitrogen fertilization of the bermudagrass lawn
  2. 14 days before overseeding
    1. Raise the mowing height 30 – 40%
    2. Decrease irrigation by 30%
  3. 1 – 3 days before overseeding
    1. Stop watering
    2. Mow at the “old” height that was before raising 30-40%
    3. Just before overseeding, lower the mowing height another 25 – 30% and leave the clippings as mulch for the overseeded seed
  4. Day of overseeding
    1. Use ryegrass seed at 12 to 15 lb/1000 ft2
    2. Apply one-half of the seed by walking in one direction and the other half of the seed by walking in a pattern perpendicular to the first pass
  5. 7-10 days after overseeding
    1. Irrigate 3-4 times per day to keep germinating seed moist
  6. 14 days after seedling emergence
    1. Fertilize with ammonium phosphate (16-20-0) at 5 lb of product per 1000 ft2
  7. First mowing
    1. When ryegrass height approaches 3 inches

Do Not:

  1. Scalp the Bermudagrass to ground level
  2. Allow germinating Ryegrass seed to dry out
  3. Aerate or deeply verticut or dethatch
  4. Use dull blades, always use sharpened mower blades
  5. Mow the grass when it is wet
  6. Over-apply fertilizers
  7. Apply pre-emergent herbicide products until after first mow

For details on the process from turf expert Dr David Kopec at the University of Arizona, visit https://extension.arizona.edu/pubs and search for the publication PDF file “az1683-2015” entitled “Overseeding Winter Grasses into Bermudagrass Turf“. 

Not Overseeding?

  • If you decide not to overseed, your Bermudagrass will thank you. The process is not heavily detrimental, but involves a lot of activity in the soil around the Bermudagrass roots while they are supposed to be sleeping. Give it a break every 3-4 years or so. 
  • Like dormant trees, dormant Bermudagrass still needs water every 15-30 days, at least 12” deep. 

Recommended sources for further reading can be found online at: