Shade grown tobacco is grown under a tapado (shade cloth) rather than in open sun. The filtered light tends to produce taller plants and thinner, stretchier leaves with finer veins. Those leaves are prized as wrapper. Connecticut shade is the classic shade-grown wrapper; similar cloth methods are used in other countries when growers want the same leaf style.
Shade-grown does not mean the plant gets no sun. The cloth cuts intensity; the plants still need light. Ecuador and some other areas can grow similar thin wrapper under natural cloud cover with less cloth. Contrast with sun grown. See growing cigar tobacco.