Lemon is native to Asia but is grown throughout the world where the climate allows. Lemons like warm sunny spots (at least 6 hours of full sun per day). Some can tolerate colder climates like UK etc. In colder climates, it is better to grow lemons in large pots that can be brought indoors or under glass over the winter to prevent the cold from damaging the plants. Lemon is grown mainly for its citrus fruits, but the leaves can you used to make tea.
Most people start by buying a small established lemon tree. This can be planted in the ground or large pot with good quality compost. Lemons can also be grown from seed but it will be about 5 years before you will receive lemons this way. It is worth removing fruit from young trees to allow the tree to focus on developing a strong root system. Lemon trees often get affected by iron deficiency (yellowing of the leaves). To prevent this it can help to water them twice a year with iron chelates. For a good harvest, it is important to regularly feed your lemon tree with a flower or fruit fertiliser.
Once the lemon bugs have appeared it can take between 6 and 9 months for the fruit to grow and ripen. Lemons are ready to pick as soon as they turn yellow (or greeny-yellow).