I have a dahlia bed, how can we help?
You can plant them closer than that -I do-that distance is if you want exhibition blooms-for cutting in the garden it is not so vital -just give them room to grow.
Have you started them into growth or are they just dried tubers?
What part of the country are you?
90cm! mine are a lot closer than that. I try to avoid the tubers touching as that can cause problems.
I started my tubers indoors and have now planted a lot of them out as they are going strong.
I planted mine out 2 weeks ago-you can plant them quite deep so if there is an unexpected late frost they will resprout-I would suggest that once it stops raining you get them in.