How can i keep ice berg lettuce from going bad?

I am not sure about shredded lettuce, but some stores sell the bags that keep vegetables fresh for a lot longer. I have used them for a couple of years and have had the heads of iceberg lettuce last for weeks without a problem. Shredded lettuce goes bad quicker, so it may last a little longer in the bags, but I don't know by how much.

I fold a dry paper towel and place it in the bottom of the container. keeps it from turning brown and mushy.

Also, don't shred more than you think you will use. It will go bad much faster shredded.

ziplock bag with a few paper towels in the bag.

"It can be frustrating when you go for that bag of lettuce you just opened the other day, only to find that it is already starting to go brown and wilt, especially when the lettuce is pre-cut or shredded. Lettuce generally doesn't last very long to begin with, but if you are trying to store lettuce that has already been shredded, it can go bad even faster if you are not meticulous. Keeping the shredded lettuce very cold and away from too much moisture is the key to maximum freshness." Read more here: https://oureverydaylife.com/preserve-shredded-lettuce-31910.html

You need a crisper, I have the old green tupperware one, but here's a new one... https://www.amazon.com/WalterDrake-Lettuce-KeeperTM/dp/B0001QNGHC/ref=sr_1_17?s=home-garden&ie=UTF8&qid=1513835080&sr=1-17&keywords=lettuce+crisper the main principal seems to be it has something on the bottom to keep moisture from touching the lettuce.

I also find the Debbie Meyer Green Bags work great.... https://www.amazon.com/dp/B00I0TBW32/ref=asc_df_B00I0TBW325308927/?tag=hyprod-20&creative=394997&creativeASIN=B00I0TBW32&linkCode=df0&hvadid=194842526382&hvpos=1o1&hvnetw=g&hvrand=4215556702295935452&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9033057&hvtargid=pla-316242243758

wrap it in paper towel

Always cut lettuce w a plastic knife! Seems to the brown away. Or tear it. I line the bag w 2 layers of towel. If it'sreally wet, i use kitchen ones. Don't crush it.