are marigolds perrienial

If they're Calendulas (English marigolds) these seed themselves and can pop up as new plants the following year. If they're French, collect the seeds and start them off in seed trays in late winter/early spring, pot them on and plant out late May (means you have to keep them somewhere warm/frost free till then). English marigolds are hardy annuals, French are half hardy annuals.

thanks for that dont know what kind they are?.have no info on them.

What do they look like - finely cut foliage with small, frilly looking heads or with open, flat heads with variegated colouring? Or softer, "normal" (uncut) light green leaves with a flower head that's like a large daisy, (sometimes double daisy like)?

save some of the flower heads when they have finished flowering .they will dry up and you can collect the seed from them .they are very easy to grow from seed so you should have even more plants next year