Lettuce is typically the staple ingredient in salads and although it is possible to freeze it for a maximum of 6 months, you shouldn’t expect it to maintain the texture that it had prior to freezing. This is because lettuce has a high water content. When frozen, this water turns into ice which affects the lettuce’s cells. For this reason, you should avoid freezing lettuce that you intend to use in salads, instead sticking with fresh lettuce leaves. The mushy texture that the lettuce develops as it freezes isn’t likely to be the most appealing. Frozen lettuce also lacks flavor in comparison to fresh lettuce and the sliminess of it can also make it difficult to work with.
Though we would recommend sticking to fresh lettuce leaves for salads rather than frozen lettuce, you can still use frozen lettuce for smoothies and soups.