Hollyhock (Alcea rosea)

We bought and planted 5 Hollyhocks last year, they grew and flowered to an enormous size. This year only 2 are showing any signs of foliage at the moment. Have they done all they will or will we get a repeat of last years blooms. If they have now done all they will do, should I have taken cuttings or seeds from them to grow for this year or do I just have to buy new ones each year?