I was just looking outside where I want the shade garden to be, and it looks like there is no shade because it is totally overcast. Is this going to make the plants die? Usually there is dark shade in that area. Thanks.

You don't see the shade because when the sunlight is blocked (overcast skies) there is no contrast between light and shadow. It's an optical illusion of sorts. If it's shaded when the sun is bright, it's shaded when it isn't bright, too.