Overseeding for Greener Lawns

The following question was sent to the P&PDL diagnosticians here at Purdue University:

Question: I don't know if you answer questions like this but, it can't hurt to try. I have a large lawn (4 acres) in northern Morgan county. About 5 years ago we planted the entire yard in Kentucky-31. We did this for two reasons, low maintenance and low maintenance. The lawn, by the way, looks very nice however, looking back I probably would have picked one of the newer tall fescues. My question is: I would like the lawn to have a little darker green cast to it in the summer. Could I start to achieve this by overseeding with Mustang or Bonanza tall fescue after aerating this fall? Would this help or would I be wasting my time and money?

Answer: I agree with your low maintenance logic and though hind sight is always 20/20, I agree that there are a number of cultivars that have the same low maintenance features as K31. However, overseeding these cultivars into K31 will be an uphill battle and it may take many, many years of overseeding to get even a noticeable darker green color. Rather consider fertilizing with slow release fertilizer at 0.5-0.75 lbs N/1000 sq ft in late May and very early July. Iron will also help turn turf a darker green. An application of ferrous sulfate at 1-2 oz/1000 sq ft every 2-4 weeks will also provide a noticeable greener lawn without increasing growth, but this should only supplement and not replace nitrogen in a typical annual fertilization schedule.

Good luck.

-Zac Reicher