They are easy enough to make, but should you choose to order that is OK too! I can't speak for success rate. I have never thrown any and then went back to check on germination. I have only done natives and perennials. Natives, especially aren't guaranteed to germinated the following spring. Many native and not native plant seeds can remain viable in the ground for years. Yellow sweet clover is an example. The seeds of Yellow sweet clover can remain viable in the ground for up to 20 years.