Coffee plants are grown in rows several feet apart. Some farmers plant fruit trees around them or plant the coffee on the sides of hills, because they need specific conditions to flourish. Ideally, Arabica coffee beans are grown at temperatures between 15–24 °C (59–75 °F) and Robusta at 24–30 °C (75–86 °F) and receive between 15–30 cm (5.9–11.8 in) of rainfall per year.[8] Heavy rain is needed in the beginning of the season when the fruit is developing, and less later in the season as it ripens.