There are quite few variables to consider when deciding on what surface a futon should be put:

The firmness of bed desired – although some customers like a futon directly on a wooden floor there are many who prefer a little more softness. If you are someone who moves a lot when in bed with elbows and other sharper parts of the body resting on the futon then it would be worth considering some extra padding under the futon. These could include any of the following:

A tatami mat (these come in quite a few different formats)

A mattress topper

A wool futon combination (either under or on top of the cotton futon)

A foam/latex mat

Cotton futon are not designed to be put straight onto bed slats as there is not the required stiffness in the cotton to make this comfortable. Some form of mat or pad would need to be put on the bed frame to allow for a dispersal of weight across the slats