Which zones?

Which zones?

I was curious what source/book people were referring to when they mentioned what zone they were in. The only source I have is Sunset's Western Garden book, where I am in the zone 4 region (south of puget sound). This book only covers the western US/Canada, and Alaska. I've notice people saying they were in New Jersey, and in the South...but that is not covered by my book. So I assume the zones you folks are referring to must be different.
Rose help?

Rose help?

Because not dying or putting yourself in the hospital is a great skill to have.

Because not dying or putting yourself in the hospital is a great skill to have.

My room!

My room!

Proud Gardener

Proud Gardener

Hydrangea help

Hydrangea help

How I spent my weekend.

How I spent my weekend.