Cinnamon trees grow primarily in tropical regions with moist, well-drained soils. The true cinnamon tree (Cinnamomum verum), also known as Ceylon cinnamon, is native to Sri Lanka and is also cultivated in nearby areas such as the Malabar Coast of India and Myanmar. It is commercially grown in Sri Lanka, the Seychelles, Madagascar, Tanzania, and parts of Borneo (Sarawak, Sabah, and Kalimantan)

. Cassia cinnamon trees, which are a different species, are native to southern China and Southeast Asia but are now mainly grown in Indonesia, which is the world's largest producer. Other significant producers of cinnamon (including cassia) include China, Vietnam, and Indonesia, which together with Sri Lanka account for 98% of global cinnamon production

. In terms of cultivation conditions, cinnamon thrives in USDA hardiness zones 9 to 12, favoring full to partial sun and acidic to neutral, well-drained loamy soils. It requires a warm tropical climate to grow well outdoors

. Summary of where cinnamon trees grow:

• True cinnamon (Cinnamomum verum): native to Sri Lanka, also grown in India, Myanmar, Seychelles, Madagascar, Tanzania, and Borneo.
• Cassia cinnamon: native to southern China and Southeast Asia, now primarily grown in Indonesia, China, and Vietnam.
• Climate: tropical regions with warm temperatures, moist and well-drained soils, USDA zones 9–12.

This distribution reflects both the native origins and the main current commercial growing regions of cinnamon trees worldwide.