Is there any point deadheading astilbes?

You can dead head as making seed takes a lot out of a plant.

I don't think that you will get any more flowers if you dead head or not as when they have flowered, thats it for the year.
I may be wrong and you could possible get more but not very likely.

I was thinking on the same lines as Katya,my two astilbes flowered lovely and it is a shame that will be it until next summer, Nickyt08, could you please explain how I go about gathering seeds from astilbes? I know you can divide them but it would be nice to grow them from seed

The seedhead go brown and the tiny dead flowers will start to open revealin gthe tiny seeds. When there are signs of them all starting to open, place a paper bag over seed head and cut off the flower stalk. Hang upside down for a week or two to allow seeds to fall out into the bag.

They have short viability so you should sow them when ripe (around autumn) and let them be exposed to winter cold.
Im not sure if they will come true to type or even germinate. I dont know how long it will take but id think you would see signs in spring time. Kepp the pot of sown seeds and seedling sin a shady site as astible like shade and esp. their young

I think that the brown seedheads of the Astilbe look almost as nice as the original flowers. I leave ours alone until the winter tidying session.