How long should grass be when I apply the nematodes ?

The grass needs to between 1 to 2 inches in length. The nematodes need to be easily washed into the soil from the blades of the grass.

Should grass be kept moist after the nematodes have been applied?

Yes, the lawn should be wet for 3 to 4 day after the application. This allows the nematodes to find the grubs and start to control this pest.

How much to water your lawn for nematode application?

Nematode need water channels to make it to the level of the grubs.  The soil moisture needed for nematodes has been described well wrung out sponge.  Another test our owner John has developed is the plug test.  Dig down to the below the turf grab a handful of dirt make a plug in your hand, now when you open your hand if said plug falls apart you need to add water if it retains its shape there is enough water for the nematodes to hunt and survive.

How much time should pass before the grass is first cut after the nematodes have been applied?

You can mow your grass the next day.