I run a plant nursery and in my field it does work this way. When plants varieties are bred they can be protected like other IP, lasting 20 years to give the breeder a chance to realise the benefits of their work. This is conditional though, the protection is only valid as long as growers/the public have reasonable access to the variety. If this is not met the protection can be revoked and it becomes public domain again, so anybody can commercially propagate the variety. Glossing over a few details, but this is true here in Australia at least.