No dwarf pecan tree exists in the United States, as of 2010. A cultivar with a compact growth habit, called Cheyenne, is available. But according to the University of Florida, Cheyenne is not recommended for use in the southern United States where pecan trees grow best.
Pecan trees grow to various heights depending on the variety. Some pecan varieties grow up to 150 feet in height although many grow to just 70 feet. The trunks can reach up to 6 feet in diameter when mature.
When pecan trees are first planted, it seems like a waste of space to plant them 35 to 60 feet apart. But when the trees reach 30 or 40 years of age, they must have 60 feet of space between them. Otherwise, the crowded trees produce reduced nut crops since the trees spend their time fighting for resources such as water and nutrients.
The trees start producing nuts when the tree is at least 5 to 6 years in age. Some pecan varieties do not produce crops until they reach 10 years of age. The trees produce heavy crops in alternating years.