Crops in FrontierVille will wither if they are not harvested in time. If a plant withers, you can only clear it rather than harvest it. It does not cost energy to clear a withered crop and the player gets only coins in return. Withered crops may be revived by neighbors when they visit your homestead.
Similar to FarmVille, the amount of time crops are guaranteed to stay ripe is equal to their growth time. This means, if you plant a crop that takes four hours to grow, it will not wither up to four hours after full growth. The crop will then have a 'cushion period'. This period is equal to half of the growth time of a crop. During this period, the crop may be harvested but, at any time, could wither.