Level 10 farmers can determine which type of crop is growing in a field, except at the lowest growth level ("freshly sown").
Level 15 farmers get tile hints when selecting a field. The stages displayed (in order) are:
# Sprouting
# Growing
# Halfway
# Almost ripe
# Ripe
# Overripe (unable to check, please verify)
Level 20 farmers can determine the growth level of a field. The levels are, chronologically sorted: