Starting perennials or biennials in the autumn

Reminds me of earlier this year when I was so happy to see some Malus hupehensis seeds from the Random Seed Swap had germinated over winter. Pricked them out into a bigger pot, left them outside on the decking for one night and the next day all the cotyledons had been nipped off. Managed to salvage one, was delighted to see it survive and grow strongly, only for it to turn out to be a rogue sunflower.