You should water not to rinse out the burn, once the blades are burnt, they're burnt, but to encourage the lawn to grow. Hopefully your grass has enough carbohydrate reserves to regenerate the blades, and frequent watering will encourage growth. Of course you will probably loose some grass, but you want to make conditions as favorable as possible so whatever is still alive will continue to be alive.

I was hoping for something more specific than Canada. I was born in Canada, so we must be from the same place! Okay, here's what you do for St John's, Newfoundland. First... Anyway, Canada is good enough. At least we know it's northern grass. May is a poor time to seed new grass. Depending on where you are in Canada, it can get too hot for new seed to survive. If you're temps never exceed 85, you have a chance. Check the lawn in August. If it is still thin, that is the time to reseed. You applied the weed n feed incorrectly. The Scott's label says to apply to a wet lawn. That would be the reason why the weed killer did not work for you (assuming it did not). But it would not necessarily indicate why it is yellowing. 10-10-10 is a vegetable fertilizer not a lawn fert. Scott's lawn ferts have N values in the high 20s. Watering You need to understand your sprinkler system whether it is in the ground or a hose with sprinkler attached. Set out some tuna or cat food cans and time how long it takes to fill them. Rather than going 20-30 minutes, this new time will be your target for watering. It might still be 20 minutes, but for me it was 8 hours. And then you should adjust to the idea of watering only once every other week. If your temps never get into the 90s, then every other week should be fine. If you really live in St John's, then you can go to once every 3 weeks in the summer. Chances are you will have to teach your grass how to go that long, so start by figuring out your target time and working to stretch the frequency out. Where I live the daytime temps are in the high 90s but I have not yet watered all my grass yet for this year. It's a matter of teaching the grass to stretch. What this does is develop deep roots which can go much longer without water. Mowing If you are not mowing at the highest setting, you should be. Fertilizing Find some organic fertilizer and put that down. One popular brand is Milorganite. I don't use it, but many people I trust use it all the time. I use alfalfa pellets (rabbit chow) at a rate of 20 pounds per 1,000 square feet. The beauty of organics is you can use them as often as you want to without any fear of hurting the grass. On the minus side, they take 3 weeks to see improvement in color. But since it would be risky to use a chemical fertilizer this time of year, your only choice is organic.

Fungus was also one of my big fears. The landscaper basically told me to make sure I watered past the first month because he said it could take that long for the Kentucky bluegrass to sprout. I watered it once a day, in the evenings for about 15 min in each spot. (3 sprinklers that i moved around.) The rye did pop up very quickly, but as near as I can tell, the bluegrass didn't come in everywhere it was supposed to. In the pictures I posted you can see some spots that are very green compared to the rest... this is where the bluegrass came in completely like I think it was supposed to. Towards the end of the daily waterings, maybe the last week or two, I backed off how long I was watered to 10 minutes. In places that seemed thin I could see that there was black stuff (a mold or fungus of some sort, I assume) that was forming on the surface of the dirt. It seemed to clear up once I stopped watering daily though. I used a combination of the Scotts Turfbuilder "Starter" and some Winterguard that I had left over from our old house and spread that last weekend. Maybe I'm just being hopeful, but it seems like the yard IS getting better. I'm a little skeptical, but the neighbors I've talked to have said that our yard looks "really good" and "way better than ours did." Which might explain why they all use lawn services now...

Where are you?