How can I keep grubs out of my garden?

Try putting beer in small saucers. They will be attracted to it and drown.

Also, crush up your egg shells and spread them around with used coffee grounds. don't like to crawl over them.

beneficial nematodes

apply food grade diatomacous earth

I don't think beer, egg shells or d-earth will help much.

White grubs are the larval stage of many insects.

Azadirachtin is a natural insect growth regulator which is derived from the neem seed (neem oil). It is a very effective grub killer to keep your organic garden healthy. Azadirachtin interferes with molting, resulting in the death of the grub.