How to Plant, Grow, and Care for Pistachio Trees

Pistachios have exploded in popularity, becoming one of the most convenient and irresistible healthy snacks. Unfortunately, a bag of healthy convenience comes with a high price tag. If your pistachio cravings are weighing heavy on your wallet, growing pistachios may be an excellent option.

A fully mature tree can produce anywhere from 20-50 lbs of pistachios. Pistachios can be stored for up to a year, so you will never have to buy pistachios from the store again. They are ideal additions to larger gardens or food forests.

Growing pistachio trees requires a lot of patience and space, but the outcome is worth it. Given a good climate, pistachio nut trees are low maintenance and ideal for gardeners of any experience level.

What are Pistachio Trees?

Pistacia vera, commonly known as the pistachio, originates from Central Asia and the Middle East. These trees are accustomed to desert climates, growing well in areas with long hot summers and cool dry winters. 

Pistachio trees are deciduous with pinnately compound leaves and flowers and fruits in large clusters. The nut or seed is encapsulated by a hard shell, covered in a gold-to-red hull. At maturity, the trees reach 20-30 feet but can be pruned to control height.

Pistachios are dormant during the winter, bloom in the spring, develop during the summer, and are ready for harvest in the fall. Although they produce annually, they will bear a heavy crop one year and a lighter crop the following year.

Pistachio trees are dioecious, meaning they are either male or female. In order for the female tree to set fruit, it must be pollinated by a male tree. One male tree can provide enough pollen for up to 11 female trees. Pistachio trees are predominately wind-pollinated, so pollinators are not required to produce fruit.

Pistachios also have a chill requirement for flower development. They require at least 1000 hours below 45°F (7°C).

Planting

Trees are typically planted as one-year-old trees in January or February. Always plant a grafted tree to ensure the correct ratio of male and female trees is grown.

Planting trees from seed is not recommended because there is no guarantee that there will be a good balance of male and female trees. The only way to determine if the tree is male or female is to wait until maturity, which takes several years. 

Choose a sunny location with good drainage and a deep soil profile to allow for the roots to expand. Growing in a container is not advised, as pistachio requires space for its deep root system.

Since female trees are wind-pollinated by male trees, do not place them in an area completely blocked from the wind. Male trees need to be planted upwind from females to guarantee pollination.

After choosing a good location, dig a hole as deep as the root ball and twice as wide. Fill in the hole with soil, compacting with a shovel when complete. Add a layer of mulch to prevent weeds and regulate temperature and soil moisture. Space trees 15-30 feet apart.

How to Grow

Caring for pistachio trees is easy. The most difficult thing about growing a pistachio tree is having patience. Pistachio trees are extremely low maintenance and well worth the wait.

Light

Pistachios require full sun. Your growing tree needs at least six hours of sunlight to achieve optimal growth. Anything less may stunt growth and prevent flowering, impacting your potential harvest.

Water

The ideal time to water is in the early morning to prevent the risk of disease. Pistachios require deep irrigation every few weeks during dry periods.

As they are drought tolerant, the trees can survive on very little water. However, providing ample moisture at the right time will increase nut yield and quality.

Drip irrigation is ideal to allow the soil to absorb large amounts of moisture. Depending on your soil type, sprinklers and soaker hoses may cause excess runoff. It is not necessary to water during the rainy season.

Soil

Pistachios can grow in a variety of soils, provided they are well-draining. Heavy clay soils are not recommended. These trees can survive in poor soil quality and are known to be salt tolerant.

Pistachios prefer slightly alkaline soils with a pH of 7.0-7.5. However, they can adapt to any soils with a pH range of 6.0-8.0.

Temperature & Humidity

Pistachios are hardy to USDA zones 7-11 and grow well in many parts of the United States, including the southwestern states of Arizona, New Mexico, and California. They prefer a climate with a hot and dry summer and cool winters. 

Frost tolerance is dependent on the rootstock. Some rootstocks can withstand temperatures below 0°F (-18°C) while others can only tolerate temperatures of 30°F (-1°C) for a short period of time before damage starts to occur.

Pistachios naturally grow in desert conditions, so they are extremely heat-tolerant. In fact, dry heat is essential for good kernel development and production. During the dormant period, temperatures above 65°F (18°C) will cause a reduction in yield.

Fertilizing

Pistachios benefit from a nutrient boost in spring to replenish lost nutrients in the soil. Fertilize once a year in the spring using a balanced NPK fertilizer, spreading the product to the drip line of the tree to reach the roots.

Pruning

During late winter and early spring when the tree is still dormant, prune trees to maintain the size and to keep the canopy open.

Choose three main branches and prune any overlapping smaller branches. Keep smaller branches anywhere from one and a half to two feet.

Keep in mind that the fruit develops on one-year-old growth. When pruning, don’t remove too many older branches, as you do need some of the more mature growth.

During the fall and winter, all leaves and fruit should drop naturally. If old leaves and fruit remain on the tree during the dormant period, remove them to avoid carrying diseased plant material into the following season.

Harvesting

Two signs that pistachios are ready to harvest are when the hull turns a reddish color and when it splits, revealing the shell below. The easiest way to harvest nuts is by laying a tarp below the tree and shaking the branches until the pistachios fall onto the tarp.

Since pistachios split before harvest, do not allow them to land on the ground to reduce the risk of contamination. Remove the hulls immediately after harvest. Failure to remove the hulls will result in shell staining and the potential for mold growth. It also slows the drying process.

Storing

Pistachios will need to be dried and stored in an airtight container. Pistachios can be dried naturally in the sun for three to four days or dried in the oven at 140-160°F (60-71°C) for around 10-14 hours. 

At room temperature, pistachios will keep for a couple of months. For long-term storage up to a year, keep them in the freezer with or without the shell.

Propagation

Pistachio trees are best propagated by grafting. The rootstocks are grown from seed and later budded with the fruiting variety.

Rootstocks used for commercial production are different species than Pistacia vera. Pistacia atlantica and Pistacia integerrima are the two most common species used for rootstocks. Hybrids of the two species have also been developed to combine the best and most favorable characteristics of the two rootstocks.

When rootstocks are large enough, they are grafted with Pistacia vera. The two most common cultivars are ‘Kerman’ and ‘Peters’. ‘Kerman’ is a female cultivar and ‘Peters’ is a male cultivar.

Common Problems

Growing pistachios is usually problem-free. However, there are some issues that you may run into.

Low Yield

Weather conditions are the number one reason for little or no crop yield. Warm weather during dormancy will prevent the tree from producing flowers.

Trees need at least 1000 hours of temperatures below 45°F (7°C). If the tree does not receive adequate chill hours, then flowering is negatively impacted. High temperatures above 65°F (18°C) during the dormant season will also cause flower loss.

Poor pollination is also a reason for poor fruit yield. Pistachios are largely wind-pollinated. The planting location should be considered to ensure that pollination will occur. Avoid putting them near a wind barrier or placing male trees downwind from females.

Pests

Navel orangeworm adults are moths with gray wings and black markings. Moths lay eggs inside split shells. Removing old nuts from the previous year will prevent or reduce overwintering pest insects. Harvesting immediately after hull split will prevent the pest from laying eggs in the nuts altogether.

Oblique-banded leafroller is another moth pest of pistachios. Adult moths are brown with darker brown oblique bands on their wings. The larvae feed on leaves and flowering branches. Bacillus thuriengensis (Bt) is effective in controlling this pest. Weekly sprays may be necessary until full control is achieved.

Citrus flat mite is a small reddish mite that appears during the summer months. Mites feed on the stems of nut clusters, as well as the nuts, causing the clusters to shrivel. Damaged clusters tend to stay on the trees rather than falling naturally during the winter providing an overwintering shelter for navel orangeworm and fungal pathogens. If treatment is necessary, citrus flat mite can be treated with sulfur sprays.

Soft scales can be found on the twigs and branches of trees. Scales excrete large amounts of honeydew which leads to sooty mold, inhibiting photosynthesis and leading to leaf drop. Scales are usually controlled with natural predators and parasites. If treatment is necessary, dormant oil sprays are effective.

Mealybugs cause the same issue as soft scales because they also excrete large amounts of honeydew. Mealybugs typically reside in the shoots and fruit clusters. If natural predators are unable to keep populations under control, pyrethrin can be used. Crawlers are the most susceptible to pesticides, so application during the crawler stage is crucial for the most effective application.

Diseases

Botrytis and Alternaria are the two most common foliar diseases in pistachio trees, causing dieback of leaves and shoots. These diseases occur when conditions are constantly wet, either from rain or high humidity. The most effective way to prevent them is to keep the foliage as dry as possible and to keep trees well-pruned to improve airflow between branches and leaves.

At the ground level, Phytophthora and Verticillium are the most common root diseases in pistachio trees. 

Verticillium starts in the roots and eventually infects the xylem. The infection will obstruct both moisture and nutrient uptake, causing wilting and eventually death. There is no treatment for Verticillium, so prevention is key. If Verticillium is present in the soil, a resistant rootstock must be used to avoid infection. 

Phytophthora is a common issue that causes root rot. This fungal issue is completely preventable with proper irrigation practices and good soil drainage. Above-ground symptoms of Phytophthora include reduced vigor and yellow leaves.

FAQs

Final Thoughts

Pistachio is a unique tree to add to your garden, whether you’re a beginner or an experienced nut grower. As long as they are planted in the right climate, they don’t need much attention to thrive.