Backyard Grass Dead Overnight

(Question)

My backyard had green grass from the beginning of spring this year & we were watering it on a daily basis & it was nice & green.But last weekend all of a sudden there were huge areas with burnt grass. I’ve attached a picture as well. We live in Toronto suberbs. My husband used a grass fertilizer last week named “Scott’s turf builder green max” not sure if there was a reaction after using this fertilizer. How do we know if there was some chemical reaction that’s why the grass died overnight or is there a way to get the soil tested to find the root cause? Please advise

(Answer)

Thank you for contacting Toronto Master Gardeners. After putting a lot of effort into caring for your lawn you must be disappointed that it died back so dramatically. Given that the die back was so sudden, I think you are right that fertilizing the lawn caused it. The directions of this brand of fertilizer state that it can be used in the summer. Currently however, the temperatures are very hot in Southern Ontario and as a general rule; it is not a good idea to fertilize during extreme heat spells. The other thing you mention is that you water the lawn on a daily basis. This can weaken the roots of grass and make it more susceptible to burning from fertilizer. It is better to water your lawn more deeply on a weekly basis. Please refer to the following links that outline general care of lawns, reasons for lawns going brown and how to repair a lawn that has been over fertilized.

http://www.torontomastergardeners.ca/wp-admin/post.php?post=3767&action=edit

http://homeguides.sfgate.com/fix-dead-grass-fertilizer-50401.html

http://homeguides.sfgate.com/save-nitrogen-burned-lawn-76736.html

https://www.gardeningknowhow.com/lawn-care/lgen/reasons-for-dying-grass.htm