Q.Sowing Rose Campions deadheads in summer, will it grow next Spring?
Should I keep the deadheads in a container and sow them during winter, or is it ok to throw them on an empty spot during summer in hope it will sprout next Spring?
Thank you in advance!

Certified GKH Gardening Expert
By the time they are completely dead, they should have cast their seeds already. Cutting them before this happens can result in immature seeds. Keeping a completely dead flower head MIGHT get you some seeds that have remained, but this is not a guarantee.
This article will help you with their care: https://www.gardeningknowhow.com/ornamental/flowers/rose-campion/rose-campion-care.htm