The vanilla plant is an orchid. It only grows in tropical conditions,15 degrees either side of the Equator.
Even in the tropics the conditions must be exactly right for growing vanilla. Vanilla vines must have shade but they need sun too. They need water but not too much. To grown a new vanilla vine you need a cutting from another plant. It's not possible to grow vanilla from a seed. This in one of the many reasons why vanilla beans have never been successfully grown in the UK.
It takes three years of careful cultivation for a vanilla vine to be ready to bear flowers. The vine must be stressed to trigger the production of flowers. These occur one at a time, and each flower has to be pollinated by hand. It's normal to see buds, flowers and inflorescences (pollinated flowers) all on the same plant. The green vanilla beans develop quickly but must be left on the vine for 6 months to reach maturity. Farmers know their vanilla is ready to be harvested when the tips of the beans turn yellow.
After picking and sorting, the green beans go through a lengthy, carefully controlled curing process.