How much time would it take to grow enough plants on Mars so that it would create enough oxygen for animals, organisms and humans breath without the aid of an enclosed ecosystem?

I’d imagine that the original colonies will of course start with a small amount of plants. But how long could it be before plants produce enough oxygen before humans could breathe the air outside?

I guess the first question should be, can plants even create successful photosynthesis and churn out oxygen with the amount of C02 on Mars? Or is there too many other chemicals in the atmosphere where plants cannot filter out those poisons to it?

Also, have we ever brought a plant to Mars? How long did it live before dying?