What do you mean by 'mini' dahlias?

Do you mean; pompons or bedding dahlias?

Yes you can store the tubers till next year!

I know what you mean - you mean the little bedder dahlias. These are so young they don't usually have a rhizome yet, but they may develop one that's worth saving by the end of the season. If they do, then store as with larger dahlias, if they don't, bin 'em.

I have stored some of the more vigorous bedding dahlias successfully. It's certainly worth a try as you've nothing to lose - just the time to store them

I've got bedding dahlias this year for the first time too, in pots. How do you tell if the rhizome is a size worth popping in the shed? Has anyone got a pic they could share? X

I grow the single Dahlias from seed,and I was amazed to see how many tubers were on some of them this year,when.I dug them up..so I saved them..they overwintered well,and are now all in flower in pots..so they are worth saving..lift them when the first frosts blacken the foliage,brush most of the soil off,and cut the stems down...stand them upside down to dry out,and brush any remaining soil off..then store them somewhere dry..I put each one in a paper bag,and into a plastic container...in a cool cupboard..my shed is too cold..and check on them now and then to see they haven't gone mouldy or soft..I also change the paper bags too,as they sometimes feel a bit damp from any remaining moisture...I know you can store them other ways,but this works for me...hope this helps...you will probably get good ideas from other members too..good luck..

Thanks for all your comments. It's the first time I have bought Dahlias(the 'mini' ones are so beautiful), I'll be saving the tubers for next year.
The Dahlias I got are called 'Patti' and 'Amy'