I planted Crimson Clover and Hairy Vetch again just now after pulling up the dead and dried out ones from my spring crop. Really I just grow these to attract and feed bees and mostly because I think they are so pretty. Love the flowers on both of them, especially the Crimson Clover.
But the fact that those plants were dead was no big deal. These are annuals and that is what they do. Grow quickly, flower and die off after flowering.