Question
We installed a section of new sod 10 days ago, replacing a cement slab that was removed. The area is about 15'X20'. My questions are about when to mow, and how long I should wait before walking on the sod or letting the dog in the area. I put up a temporary fence to keep the dog and grandkids out, as well as ME. The farm which supplied the sod suggested heavy watering for two weeks, but not when to mow or walk upon it. Our dog is female, so I know she can hurt ANY lawn, which will be inevitable.

How long do you think I should leave this fence up, and when should we start mowing? It looks great so far.

Answer
Pedestrian traffic technically can be admitted as early as a week after Sod goes down, provided it's light-footed and brief, and preferably in the morning when the air is still cool.  A month is better, and mandatory if you're going to do things like BBQ'g and other activities that will clobber your new Grass.  

Remember, your new Sod must stay CONSTANTLY moist after installation.  This is the step where most homeowners mess up.  That's no small loss considering lots of people drop $20,000 to install a new Sod lawn.  But many of them just do not comprehend the extent of damage sustained by Sod roots before it gets rolled out.  For every hour spent out of the ground, root fibers were drying and dieing.  Turf must build new root tissue from scratch, then send it down into a new soilbed.  Sod must be handled like a delicate, root-less cut flower, irrigated VERY carefully for 10 days like baby Grass, especially toward the edges where roots were exposed.

Pick a cool morning for the first cut.  Grass loses moisture every time you Mow; you'll lose less if you Mow during one of the cooler times of the day.  Cool Season Grass Sod is generally mowed 7 to 10 days after it gets rolled out.  After you Mow, continue to irrigate daily, but on a slower schedule, until you're down to an inch a week (including natural precipitation).  Check to make sure the turf is thoroughly wet by lifting a strip up at the corner; if it is difficult to lift, and you can see some white root sprouts, you're almost there.

Try to get everyone and everything to Keep Off The Grass, at least until that pricey Sod has sprouted healthy roots.  And unless you had a bed of rich, healthy, organic Soil waiting for your Sod, the new Lawn is going to need a good Nitrogen feeding a Week or so after the first Mow.

When should you NOT Mow?

NEVER mow new Sod when it feels soaked with water, or if it still feels soft.  The mower should be set to cut high, ideally around 3 inches -- and higher to avoid breaking the rule about removing more than 1/3 of the blade.  More than that and you're guilty of Scalping -- which can and will cause permanent damage to a new Lawn.  Remove clippings and compost them -- this is not the time to stress Grass out with obstructions to Sunlight and the high-moisture/limited light setup for potential Fungus attacks.

Your Dog question is a problem faced by everything who ever owned a Dog and a Lawn.  Some Grasses are slightly tougher than others when it comes to those canine calling cards, but it's a little late for that information.  Teaching Fido to GO in the same spot, preferably one without Grass, is the key here.  Otherwise, you will have to chase your Dog all over your new Sod with a hose, ready to dilute anything she happens to apply to the Grass.

While you're watching your new Grass grow, pour yourself a new tall Long Island Iced Tea and read this witty essay on the question of the hour, 'How YOU Can Botch the Start of a Sodded Lawn!' by a Turfgrass Professor at University of Illinois, Dr Hank Wilkinson, posted at the Turf Resource Center website:

http://new.turfgrasssod.org/pressroom/botch_sodded_lawn.pdf

Thanks for writing, Dennis.  Keep me posted.