A dwarf lemon tree is like a regular lemon tree. However, it is one that has been grafted on to a smaller root. This grafting process helps limit its growth in size.
Dwarf trees typically reach 8-10 feet tall, compared to the standard trees, which grow up to 20 feet. Under particular conditions, some can reach up to 15-20 feet. This all depends on the type of rootstock it is grafted onto.
There are different varieties of dwarf lemons, and the reasons for being bred vary similarly. Some are particularly bred for ornamental purposes, while some are bred for their taste and size.
The standard Meyer lemon tree, asides from being available in a dwarf variety, is naturally small, measuring somewhere between 6-10 feet in height. So you can easily grow one of these trees in a container even without using a dwarf rootstock.
The standard Lisbon lemon tree typically grows 15 feet high, which may be smaller if you put them in a container. However, if you put them in the right conditions, you may see them grow up to 30 feet in height with a width of 25 feet. The dwarf variety grows as tall as 8-12 feet..