Growing lettuce in the garden is so rewarding. This easy-to-grow, cool season vegetable can be ready for harvest in as little as 40 days after sowing. Lettuce seed can be sown in the garden in early spring when the ground can be worked. Planting lettuce seed every few weeks ensures a longer harvest. Lettuce can also be planted in late summer for a fall harvest. Lettuce can be planted in full sun or partial shade. It doesn't care for direct afternoon sun in the heat of the summer. When choosing lettuce seed to buy, choose from a variety of lettuce types including loose leaf, butterhead, romaine or cos, and crisphead. Lettuce can be grown in the garden, raised beds and containers.