Pecan and pistachio trees are considered temperate climate trees. Therefore, in Hawaii and other tropical areas, optimal production would, in all likelihood, not be possible. The trees will grow, but how much fruit will they yield? Pecans require 250 chilling hours (number of hours below 45 degrees Fahrenheit) before they will produce a good crop. This chill factor will not be met in Hawaii, yet trees will still yield some fruit. Although growing pecans at a higher elevation will give them a better chance to fruit, they also require a hot summer climate to mature the nut. In addition, two different varieties must be planted together for good pollination and better production.
A mature pecan tree is growing at the Kainaliu Experimental Station on the west side of the Big Island. Elevation is approximately 1,300 feet. The tree is sporadically deciduous – loses its leaves, and over the years it has produced pecans. The variety is unknown.
There is also a Hall's Hardy Pecan growing at 1,200 feet near Pahoa on the Big Island. It has produced some nuts, but it is still young. Rainfall is 200 inches annually.
Pistachio trees need 800 chilling hours and require long, hot dry summers; male and female trees must be planted. Obviously, pistachios will not produce well in the tropics.
A large portion of the world’s Brazil nuts comes from Brazil and Bolivia. The trees should grow in Hawaii, yet they may not yield good crops. The flowers can only be entered and pollinated by large-bodied bees with enough strength to pry open flowers in order to get to the nectar. It is unknown whether there are adequate large-bodied bee populations in Hawaii.