I start watering in May/June depending on the amount of rain we've had. I typically stop watering by the end of October, but this year has been so dry that I will probably be watering later than usual. As for winterizing the system, that usually happens sometime in early November.

 

@massgrass Perfect! That helps a lot, just needed a general guide line to follow so I will follow yours in combination with the weather. Thank you!

 

I should also mention that I try to do my system startup in April so I have time to make any needed repairs. I occasionally have to replace a head or zone valve, so it's nice to have a little time to get parts and fix it before irrigation season begins.

 

Hi Guys -
Just wanted to note that this is really helpful to me as well. I am a lawn newb and an irrigation newb. Bought a new house beginning of this year and I'm still fighting the lawn a bit. My plan was to winterize the irrigation mid October mostly because I worry over frost/freezing but I do have more apps to put down and want to water in. I was going to time application with rain but maybe I'll wait until the end of the month.
The reason for my post too is to note I'm also in Massachusetts (and in Natick like @Ryanmorales88 )

 

I was wondering when do I stop/start watering grass? I am sure there is no exact date, but what temperatures overnight am I looking for to start winterizing the sprinklers and also to start up again? As mentioned in the title I am in Massachusetts(Natick).

This is tough call for us northerners. I'm in your area, about 50 miles north of you. Even though the lawn's water needs decrease greatly getting into October, with shorter days and less sunlight, it can be trouble for a lawn if there isn't any rain at all (which is how our weather has been here lately.) I think @massgrass advice is pretty much spot on for your area.

The initial frosts aren't going to freeze an underground irrigation system. The sprinkler heads in the ground and underground piping aren't going to freeze until the ground starts to freeze, which is quite a bit later.

The most vulnerable part of the irrigation system to an early freeze is usually right where the plumbing exits the house and goes to the backflow preventer. As to whether or not the water will freeze in there on a cold night depends a lot upon the specifics of the exposure of that plumbing to a clear sky, the wind on the cold night, how far it is from the house, etc.

We have done renovations six of the last eight years, so we're always wanting to keep the irrigation system active as deep into fall as possible. "Average first frost" in our area is September 26th. We usually have the irrigation system blown out during the last week of October, which is basically a month after that.

I don't worry about it unless the forecasted temperature is below 28F, however our plumbing and backflow preventer are just a couple inches from the house, in a sheltered corner, in the back of our house where it has hardly any direct exposure to the sky. On nights when the forecast is for below 28F, I'll wrap a big blanket around the backflow preventer and the few feet of exterior plumbing above ground. In some past years when the forecast was around 20F, I set the irrigation controller to water one zone for 10 minutes every 2 hours, just to keep some flow through the backflow preventer. I haven't had anything freeze yet, but it's always a concern.

The safest thing to do, of course, is to get it blown out before any freezing temperatures. However, one can keep it going longer with some care and a bit of worry...

Oh, and we have this year's irrigation blowout scheduled for October 22nd. A little earlier than I'd like, but we'll make it work. I'm hoping to have mowed at least a couple times before then...

 

If it helps, I didn't have a hard frost until October 24th last year in Bristol County, MA. Still plenty of time after that to get the system winterized.