I bought a mattress from Ikea 3.5 yrs ago. It has delveloped a sage in the middle. Do I just bring it back to the store, or is there a process I have to do first?

I would call them and ask before attempting to return it.

3.5 years for an ikea mattress ... not bad

Sage? What it grew a herb?

Why do you ask on here? Why don't you actually talk to them instead of posting on a random Google forum?

Call

Their return policy is 1 year and I'm pretty sure there's no warranty for mattresses

I'm looking to grow herbs indoors, sage worked okay for you?

Are you Swedish? It's been 3.5 years. Time to buy a new mattress.

There is a 15 yr warranty on mattress.