60-70 days. Buttercrunch Lettuce Seeds. Lactuca sativa. Non-GMO. Open Pollinated. An award-winning and absolutely hardy cultivar of butter head, Buttercrunch is tender, delicious, and looks as good in the garden as in the salad bowl. First introduced by Cornell University in the 1960s, Buttercrunch debuted as the 1963 All-America Selections vegetable winner for its tolerance to stress, poor soils, and bolting from spring warmth.