Hello Sandi,

The deep, infrequent watering recommendation has mostly been promoted by city water managers because they know the more frequently homeowners water, the more water they will apply because they don't know how much water to apply with each watering.

As long as you are watering at the correct time, meaning early morning, it is generally better for the grass to be watered more frequently, because the soil maintains a more consistent soil moisture and the grass does not get stressed.    This recommendation is especially true if you have sandy soil because the sand can't hold much water.  In western Oregon, however, most of us have clay, loam or silty, clay, loam soil, which holds water well.

There are exceptions when too much watering can cause fungal disease problems but this is most often caused by watering during the day time.   

The best interval for clay soils is probably every other day, but every 3rd day can work too.  If you are trying to save water, our research shows, you can get better turf quality by watering 3 days a week vs. one day a week, assuming you are applying the same amount of total water.  For example, instead of applying 1 inch of water 1 time, you would apply 0.33 inches of water 3 times.   

In our trial, we applied 1 inch of water a week all summer to perennial ryegrass.  This amount turned out not to be enough when temperatures got hot (near 100) in mid to late August.   It is likely that 1.5" of water a week would be needed to keep the turf green during these times.  However, as the plots dried out, those that received water more frequently, stayed greener much longer.  Keep in mind, that this study was done with small plots, each of which had 4 irrigation heads, so the plots were watered uniformily.   Most irrigation systems do not apply water very uniformly, so you either end up with dry spots or over water to eliminate the dry spots, unless you supplement with hand watering.

The caveot to this approach is that you know how much you are watering.   Grass will take as much water as you give it so if you over water it, generally, you won't know it and you will apply too much water.  To put the correct amount of water down requires knowing how much water your system applies, paying close attention to your lawn, and adjusting the run times, when necessary.   You are getting pretty close to applying the correct amount when you are seeing a little bit of drought stress in places.

You can tell how much your system is applying by putting tuna cans or some other small container on your lawn and running your system for 1 hour.  Then you can measure the inches caught in the container.   Most irrigation systems using rotary heads or pop-up heads with rotator nozzles apply about 0.25 inches of water an hour.  Popup heads with spray nozzles can apply an inch of water or more per hour, but these nozzles are most often used in landscape beds.

Most homeowners who have irrigation systems (not that many) turn on their systems and just let them run.   If they are lucky, the run times get automatically adjusted based on local weather, but not many have this feature.

The take home message is it is better for your grass to water more frequently than once per week.  And, you can use less water and get the same turf quality.  However, using less water requires effort and vigilance on your part.   If you simply run your system more often, you will likely over water.

The goal of irrigating after seeding is to keep the surface moist without allowing the water to puddle.  If you mulch the seed with peat moss, or some other light compost, you can water much less frequently.  If you not mulching, I would water 4x a day, once in the morning, once around noon, and twice in the afternoon.  With an irrigation system, we generally water 6 minutes with each watering.  I would watch it the first time and see when the water starts puddling.  Then set the time to be shorter than that.  

Depending on how dry the soil is when you start, I usually soak the seed in well on the first watering and then run the system for 9 minutes for each watering on the first day (as long as it doesn't puddle) and then cut back to 6 minutes after that.   These times are just a guide to meet the goal of keeping the soil moist.   

If it is cloudy in the fall, you can probably limit watering to twice a day, but it depends on temperature, so use your judgement and adjust as necessary.

The seed should germinate in 7 - 10 days unless you plant Kentucky bluegrass or hard fescue that can take 2 - 3 weeks.

After the seed germinates, cut back watering to once in the morning and once in the afternoon (unless it's hot, you may want to supplement one more time).  After a week or so of growth, water more in the morning (longer run time) and supplement only if it's warm.  After 2 weeks of growth, you won't have to water in the afternoon (unless it's in the 90's).

Before your first mow, skip watering for a day or two and let the soil dry out and firm up so you don't rut the soil with your mower wheels.

I hope this helps.  Good luck.