isn't all lettuce kosher ?
All products that grow in the soil or on plants, bushes, or trees are kosher. However, all insects and creatures that have many legs or very short legs are NOT kosher. Consequently, vegetables, fruits and other products that are known to be infested with insects must be washed to remove the bugs and checked to confirm the produce is insect free.
Israel Ellen is the owner of Kosher Crops - the industry leader in ultra washed produce and pre-checked vertically farmed greens.