Yes - but you might lose the dahlias anyway in the ground, they tend to rot if left in damp soil, that's what gets them rather than just cold.

Yes. Some I cover in a mound of compost and some I lift and store and both systems seem to work. A nice big mound over each one.

Thanks, I will do it tomorrow.

I would wait till the foliage dies back after the first hard frost. That may be this time next week...

OK - next week then!

If your soil is light, then your mulch will help to protect the tubers. If you have a heavy soil, I would be inclined to lift them and store them in a frost-free environment for the winter.

Thanks. My soil is light and they usually come through the winter. Just wondered if a mulch might help.

A bark mulch will help Edwinarobari. It is wet soil that causes the damage as when it freezes and thaws and refreezes that rots the dahlia tubers over time (as Bamboo has said). They make a terrible smell when they rot - not a nice thing in spring when you have plans for them!

If you store them over the winter say near a south or west facing wall, then the wall will help provide some heat as well as deflecting some rain and a heavy mulch (say an inch or two thickly packed around the tubers) then they should come through winter.

I put them in sand (childrens play sand is good as it keeps a certain dampness and it is cheap this time of year) in my garage. Builders sand is also more than fine but you may need to spray them lightly with water every month or so as you do not want to desiccate them. If you have Gladiolus then also store them like that after the corms have been cured (2-4 weeks after taking them out the ground)