Lemon trees adapt well to container culture and are quite attractive, making an interesting addition to the patio or a sunny room. They bear glossy green leaves and fragrant white flowers in late winter. Fruits take several months to mature, making the container-grown lemon visually interesting all year. Container-grown lemon trees on average will reach a height of between 4 and 6 feet, but can, under the right conditions, grow as tall as 10 feet. They have also been used as bonsai subjects. They are not the easiest plants to grow, but well worth the effort.
Choose a dwarf lemon variety that is suitable for container culture. There are some natural dwarfs but most dwarf varieties are full-sized trees grown on dwarfing root stocks. The fruit they produce will be full size.
Choose a suitable container. It should be large enough to accommodate the root ball with 2 inches to spare. A 10- to 14-inch pot is a good size for a young tree. Eventually it will need to be transplanted to a 16- to 20-inch container. The larger the tree is allowed to grow the better the fruit production. The container will also need a drainage hole.
Fill the bottom 2 inches of the container with pebbles, stones or broken crockery. This will facilitate drainage. Lemon trees prefer moist but not wet soil. If your container is large, place it on the saucer before filling it. Add some potting soil. Turn the lemon tree on its side and slide it out of its container by grasping the trunk. Set it in the new container and fill around the root ball with more potting mix. The top of the root ball should be sitting just under the surface. Do not plant too deeply. Cut back the top growth by a few inches to encourage root growth. Don't fertilize until after new growth begins. Water thoroughly, until water runs out of the drainage hole.
Place your tree in a sunny location. Lemon trees need lots of light. A southern exposure is best. Some varieties will do well in partial shade but fruit production will fall. In warmer climates, container-grown lemon trees can remain outside year-round. Lemons are sensitive to freezing and will need to be moved indoors when temperatures fall near freezing. Container-grown plants will freeze earlier than plants grown in the ground. When temperatures fall below 55 degrees lemon trees will go dormant.
Check the moisture level 1 inch below the surface with your finger. If the soil feels dry water the tree thoroughly until water runs out the bottom. If the surface is very dry break it up a little to facilitate penetration. Mist the plant if the humidity level is low.
Fertilize your tree in spring and summer with a balanced fertilizer. Lemon trees are heavy feeders and need a lot of nitrogen. In warmer areas you may be able to find fertilizer formulated for citrus. They do not need fertilizer in the winter.
Prune the tree after most of the fruit has ripened. Prune off any dead or diseased wood. Thin out any thin, weak branches to increase air circulation.