Hardiness of Dwarf Lemon Trees

Rootstocks

• Dwarf rootstocks allow lemon and other fruits to grow to about 10 feet tall, whereas full-sized trees grow to more than 30 feet tall. Even though the fruit is lemon and the tree is called a dwarf lemon tree, it is actually a combination of a grafted portion, or scion, of lemon, on a rootstock from either a sour orange or trifoliate orange tree. The University of California says many dwarf lemons are grafted on “Flying Dragon” trifoliate orange rootstock. Trees are usually grafted onto different rootstocks because of the rootstock’s resistance to different diseases or pests -- this is regardless of dwarf or full-size status -- but the fruit still has its own requirements.

Advantages

• Dwarf trees fit in containers, so gardeners can move them, if on wheeled pallets, into protected areas when freezes are expected. Even if the dwarf lemon trees are planted in-ground, the shorter size makes covering them much simpler, instead of trying to haul a tarp over a 30-foot tree. Trifoliate orange dwarf rootstocks can also develop better cold hardiness if left in an area with consistent temperatures; the University of Florida notes a temperature range of 70 degrees Fahrenheit in the day and 50 degrees Fahrenheit at night help trifoliate orange become better able to handle cold temperatures. If the temperature stays above 50 degrees, though, the development could be stopped.

Problems Affecting Hardiness

• The University of California advises that dwarf rootstocks are less drought-tolerant than other types of rootstock. This means you have to be careful to provide the tree with enough water and not neglect it. There may also be more suckers poking up from the roots, which can compete with the main tree for nutrients. The University of Florida says that rootstocks that have been dwarfed by the experimental addition of a virus-like organism called citrus exocortis viroid were shown to be less able to handle freezes than non-infected rootstocks. Finally, the type of lemon will still influence the hardiness, with varieties like Meyer and Lisbon being more cold-tolerant than varieties like Frost Eureka.

Cautions

• The Meyer lemon is a very common dwarf lemon tree, and while Meyers tend to be fairly hardy, they are actually illegal in some areas due to its ability to transmit a citrus virus. Many companies claim their dwarf Meyer lemons are disease-free, but check out who does the certification, or if the tree even has any sort of certification. For example, a company’s tree might be certified by one state’s department of agriculture, while another might not provide a name.