I'm curious, too!

I don't think Astilbe grows from bulbs. Maybe I'm wrong, but the ones I've got are hardy perennials and form clumps in the ground.

Astilbe have thick roots which can be called bulbs if one prefers to call them that. Just plant them directly in the garden early spring, they’ll pop up fast enough. Remember to keep the soil moderately moist though since they don’t like to be in soil that repeatedly dries out.

Thick roots do not form a bulb. You can 'call' it that if you want but you'd be wrong.

Take it easy Hywel:) xxx!

lol ... I studied Botany so I like to name things properly. :)

garden center sent me a free astible they said it was a bulb forgive me if i am wrong us oap do make mistakes somtimes

Hi the astible has a fibrous root system and sadly many garden centres call everything that's thickened a bulb, even if they are not. So don't worry Bigalfie. If they are potted up then I would move them out into a cold frame or sheltered spot, the warm greenhouse will encourage them to grow too soon. Come March/April, providing the ground isn't frozen, they can go into the open ground. If you want them in an ornamental pot then that is ok too.
The ones I have are in the open ground and dormant at the moment. I have left the old flower heads on; the birds enjoy the seeds and they add a bit of winter colour and shape in the depths of winter.

My bulb supplier offers bare root Astilbes--which I don't bring in, since they don't grow here--and so do many other bulb companies, which is probably a big source of confusion. Not that the public isn't already sufficiently confused--every year, I get several requests for "rose bulbs"! :)

Rose bulbs!! Now that really is a new one.