One thing you discover after being around a lot of self storage units is that almost everyone has a mattress stashed in their unit. It seems to be a standard that if you rent a self storage unit you are required to put a mattress in it. Before you follow the leaders in this area though you need to take a careful look at that mattress and ask yourself:
"Is this really something that I will use at some point again in the future?"
"Will I really want to sleep on this thing again?"
"Would I want any of my friends or family to sleep on this mattress?"
If you answer "no" to any of the above questions then you just need to throw that mattress away! Of course I'd be happy to rent a unit to you and store it for the next 5 years, but chances are it's going to end up in a landfill before it ever gets used again. Just pay the money and take it to the dump. You'll be ahead in the long run.
If you answered "yes" to any of the above mattress questions then the next step is to consider how you are going to store your mattress.
The first and most important step is to get a mattress bag. If you are tempted to skip this step then you might as well procede as if you answered no to all of the questions and throw the mattress away! If you store a mattress in a self storage unit without a mattress bag, it will collect more dust than you ever thought possible and be ruined for future use. Any dampness from the concrete floor will be absorbed by the mattress. It's also an easy target for any vermine. So, buy a mattress bag or save one from a new mattress. Slip it over the mattress and tape it up with packing tape. If the bag rips in transport, tape that opening up as well. You can buy these bags at your storage facility or a moving/packing supplier and they run around $5.00 or less depending on the size.
The next step is to consider pest control. Most storage unit doors open to the great out of doors and it is possible that critters could get in through the cracks and crannies around your unit. A tray of rodent pellets should keep the mice and rats away. Some roach traps or feeders would be a good idea although they are less likely to make it through a well sealed mattress bag. Remember that these need to be replaced periodically. If spiders are a problem, the best solution we've found is to set off a spider bomb in the unit although this would permeate any items that are not sealed in plastic.
The final step is to check your unit occassionally. This is the best way to make sure that your mattress and other valuables are in good condition and not deteriorating while in storage. These same tips of course apply to a matching box springs! Good luck with your mattress and all your storage needs!