Cosmos - Perennials or Annuals?

Last year I planted cosmos and they grew and bloomed amazingly! Just a few days ago I was cleaning out my garden and I decided to completely chop back the old dead-looking cosmo plant. It was completely dried our although it looked like it was really rooted. Did I make a mistake? Do Cosmos come back from the old plant or do they just reseed themselves? I am in Toronto, Canada. I am almost positive that the cosmos I've seen just reseed and come right back.

Will my cosmo come back?

 

Most Cosmos varieties are annuals, including Cosmos bipinnatus on your picture. It will probably grow for you again from last year's seeds. Be careful not to pull the new seedlings up.

 

Thanks a lot. I feel a lot better knowing there`s a chance it may come back.

 

If it didn't you can buy a packet of seeds and sow them yourself.

 

Thanks, that's a great idea. They do grow very fast:)