Lemon trees, like any citrus tree, thrive in warm, sunny conditions. Northern gardeners may grow dwarf varieties indoors in containers. With adequate light and water, even indoor trees will produce fruit. Lemons are highly acidic and are used primarily as a flavoring and for their juice.
Lemon trees are the most cold tender of citrus trees, according to Texas A&M University. True lemons originated in India and are grown by commercial and home growers in warm climates. Meyer lemons came from China, and while technically not a lemon, are used as a lemon substitute. They are more cold-hardy than real lemons and have a thin skin. Meyer lemons carry a virus that infects real lemons and causes considerable damage to commercial crops. Newer virus-free types are preferable.
Lemons grown outdoors grow best in full sun. Because they are cold-tender, they should be planted near a house or sheltered area in a south or southwestern location. Trees growing nearby may provide shelter, but shouldn't be larger than the lemon trees, obscuring sunlight.
The compact form of Meyer lemon tree makes it a good choice for container growing. These trees must have a minimum of six hours of sunlight per day for good fruit production. A bright, sunny window might be enough, otherwise a grow light is recommended. The grow light may be left on from sunrise to sunset.
In northern climates, container-planted lemons may be grown outdoors from spring until fall. A few weeks before temperatures dip, the tree is moved to an outdoor area with partial shade. This allows the lemon tree to slowly acclimate to less light and minimizes shock when it is brought indoors for the winter. The tree must be brought in before temperatures reach 32 degrees. In the spring, the process is reversed. The lemon tree is once again placed in partial shade and then moved to a more sunny location.
When lemon trees are moved indoors for the winter, they require less watering. In fact, too much water may cause the roots to rot. They should be kept slightly dry. While many fruit trees benefit from mulching, lemon trees may develop foot rot if mulched, advises Texas A&M University.