David M. Kopec, Extension Turfgrass Specialist
Late September and October means overseeding time. Just after the bermudagrass has made its final push to fill in and look healthy for the last month to six weeks, it's time to overseed again!
Overseeding is tough, because it's simply a competitive state against bermudagrass. Tifway is much better at transition, than common is, simply because of increase shoot density for the Tifway (428).
Ideally, overseeding should take place when the nighttime temperatures are about 55F (low) and the daytime temperatures are 80-85F. There is plenty of data around to estimate when this occurs in your area. Moreover, club schedules dictate overseeding dates. Too early, an overseed often results in extreme regrowth (competition) from the bermudagrass, poor ryegrass tillering and in some cases, poor germination of the ryegrass itself.
When overseeding, here are some "easy ways" to think like a plant.
Fairways and Roughs
1) Stop nitrogen fertility 25-30 days before overseeding. Substitute and/or maintain potassium fertilization.
2) Decrease the irrigation starting at ten days before overseeding. Skip every third irrigation, or apply 2/3 the normal amount required, per irrigation event.
3) Ten days before overseeding, raise the mowing height by 35%. Mow on a regular schedule at the new height.
4) Three days before overseeding, remove 40% of the grass height. This will leave you with an upright stolon, with hopefully only two lower leaves on it. Remove the clippings. Shut off the irrigation.
5) At one day before overseeding, brush up the stolons to alleviate them and scratch up the small amount of "new thatch" you have. A spring tine rake is suitable as well.
6) Overseed in two directions. Drag the seed into the turf with either a steel drag mat or a weighted chain link fence with a carpet wired underneath it.
7) Scalp the grass, returning the clippings. The clippings will serve as a mulch and will then decompose or be mowed up later.
8) Irrigate 3-4 time/day until emergence of seedlings.
Sand Greens and Sand Tees
1) Hopefully, you have minimum thatch from aerification, topdressing and any summer verticutting.
2) Stop -N- fertilization at 25 days before overseeding. Substitute or maintain potassium fertilization.
3) Seven days before overseed, decrease irrigation amounts. Apply 2/3 of the regular amount, per irrigation.
4) Five days before overseed, raise the mowing height by 1/16".
5) Three days before overseeding, raise mowing height another 1/16".
6) If the greens are actually growing mow for the last time one day before overseed.
7) Lightly verticut in a minimum of two directions.
8) Overseed in three directions.
9) Topdress in two directions. Apply a total of about 3/16" to 1/4" of sand. Roll the turf with a weighted roller.
10) Irrigate 3-4 times checking for germination and emergence.
Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director, Cooperative Extension, College of Agriculture & Life Sciences, The University of Arizona. The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.