Question
We have recently had a new lawn laid (8 days ago). We then had a fall of snow which is lying on the new turf to a depth of 3 inches. Do I continue to water the new turf? Forecast is clear and dry for the next two days with air temp 4-6 degrees Centigrade.

Answer
You do not need to water the turf as long as it is snow covered. Evaporation is reduced due to the snow cover. once the snow cover disappear resume watering.

The best time to establish a new lawn is when the soil temperatures are between 10 and 20 deg C. Rooting of the turf into the soil is going to be most successful at this time. Putting down sod while temperatures are consistently below 10 deg C especially when snow is still a possibility may not give desired results. E.g. you risk problems with rooting.

You will need to feel the surface of the soil after the snow disappears. gently lift one corner of a sod piece after snow disappear. feel the soil below (poke with a screw driver). If it is very moist then do not water. if it is moist (but not saturated) continue your normal watering pattern. If it is dry, water once really well (for a long time) and then resume your normal watering pattern.

In cool weather, evaporation is usually very limited and you can easily overwater. you want to keep the top 3 cms of soil below the turf consistently moist, but not soaked. Check a different corner on a different piece every few days (e.g. don't use the same piece or it wont root properly). Once the turf is rooted (you can not lift a corner) stop checking but continue to water for a number of weeks.