Question: My husband asked me to contact you about how to trim our pistachio nut tree and how to get it pollinated.
You can still do some light pruning on fruit and nut trees. On your pistachio, I would cut back the new growth to about 18 inches above where you see the spurs growing. If this is too severe, then I would just cut back last year’s growth so that it is only about 12 to 18 inches long. Pistachios come as both male and female trees. You will need a male tree somewhere close by because they are wind-pollinated. The male and female may be planted in the same hole, about 18 to 24 inches apart, but the male tree is more vigorous and will have to be cut back harder than the female to keep it under control. If planting in the same hole, you should put a male tree on the north side so that the female, the less vigorous of the two, receives more sunlight. Otherwise you will have to rely on a male tree from a close neighbor or plant your own.
Bob Morris is a professor emeritus in horticulture with the University of Nevada and can be reached at firstname.lastname@example.org. Visit his blog at xtremehorticulture.blogspot.com.