Peppercorn berries grow in clusters, like grapes, albeit much smaller. The berries for black peppercorn are picked about a week before they are ripe, when at least one of the berries in the clusters shows yellow. As the berries dry in the sun on straw mats, their outer layer shrivels and turns black. For white peppercorn, the berry is as ripe as the farmer feels comfortable leaving it on the vine; some of the berries in the clusters show yellow, and at least one will show reddish-orange. Green peppercorns are picked at the berry's most immature stage, several weeks before the berries are ripe.