Why didn't my seeds germinate?

Before you throw it out

Dig up a few seeds. Firm and pale means alive; soft or dark means rotted. See when to give up and the types of seed guide. For seedlings that came up but look wrong, use the problem picker.

Answers are matched to advice from the RHS and from Clemson, Penn State and Oregon State extension services. This is a guide to likelihoods, not a diagnosis.