I rip out the old plant and drop seeds everywhere

Hang on lad, just buds will = no flowers yet. Up our way they're still in flower.
Unless you are "Des Parrot" leave until you've no options left and see if they flower.
Had a look around
Found http://www.ext.nodak.edu/extnews/hortiscope/flowers/hllyhock.htm

Where 1st answer said...

A: I wouldn't rip out all the hollyhocks. Keep just enough plants to keep your garden from looking weedy. You may have biennial hollyhocks that require another cold period before they will flower. Lilacs will flower every year if you harvest the flowers. The flower buds are set for the following year on the subsequent growth that takes place after they flower. If you prune the plants late in the summer, you will remove the flower buds for the following year."

Yes they are biennial so they wont flower until next year will they?? I have only grew them from seed this year so I just leave them and stake them up? thanks

Dont whatever you do rip them out. They are biennials they grow leaves the first year and flower the second. I grow lots and after flowering I leave them till the seeds are ripe and then I cut them down to just above ground level. I would treat yours the same when the leaves have gone over then cut them to about 3" above ground. Even after they have flowered I would never rip them out as they reappear for years.

Kate, I just noticed you only sowed them this year its my experience that some might not flower till the summer after next so dont give up.

I agree with Drc there, the first year i had no flowers but every year since we have had flowers, and i only cut back to just above ground level after seeds have formed and leaves are gone...