Caring for pistachio trees is not difficult, and once they begin producing nuts, they require very little attention. In their early years, it’s necessary to establish a good open shape to facilitate light penetration through the tree and air circulation around it. Let’s find out more about how to care for a pistachio tree.
What You'll Learn Today
- Are Pistachio Trees Easy To Care For?
- Do Pistachio Trees Need A Pollinator?
- How Much Water Does A Pistachio Tree Need?
- How Many Pistachio Trees Per Acre?
- What Is The Lifespan Of A Pistachio Tree?
- Can You Eat Pistachio Straight From The Tree?
- How to Preserve Pistachios
Are Pistachio Trees Easy To Care For?
Pistachios trees are easy to care for, as they only require several basic things – heat, light, water, nutrients, and a little annual maintenance.
They are deciduous trees and are heat lovers enjoying hot summers (100°F) and dry heat conditions. They also need winter to be cool, so they become dormant. This combination produces the best quantity and quality of nuts.
They grow best in hardiness zones 7 to 11. They are native to western Asia and Asia Minor, stretching from Syria to Pakistan, although they are now grown extensively in Australia and other places where the conditions are right.
If you plant a young pistachio tree, you’ll need to be patient, as it will be some time before you’ll see any nuts. On average, it takes around eight years before the trees begin really fruiting, and peak production can take 15 to 20 years.
The best soil for growing pistachios is a deep sandy loam. They send down a deep taproot to seven feet or more, so shallow soils are unsuitable.
The poorer the soil, the closer together the trees should be planted.
Feeding Pistachio Trees
When your trees are young, it’s best to ensure they have sufficient nutrients to grow big and strong.
This can be done scientifically, or not. A simple method is to apply well-rotted manure or compost around the tree’s base every spring. This not only helps feed the tree but also improves the soil.
If you want to be more technical, a soil analysis lets you see what nutrients are deficient and it is then possible to fertilize accordingly.
Remember that the basic needs are Nitrogen (N), Phosphorus (P), and Potassium (K), as well as other macronutrients that will be present in a good quality fruit tree fertilizer. Zinc is an especially important macronutrient for nut trees.
By feeding a 10.10.10 fertilizer mix in late winter or early spring, will do more good than harm, providing you follow the manufacturer’s instructions on quantities and mixing.
Another method is to monitor your trees closely and see what they need.
- Nitrogen (N) – encourages plant growth and leaf development
- Phosphorus (P) – is required for strong roots, fruits, and seeds
- Potassium (K) – promotes flower production and fruiting
Always ensure you keep chemical fertilizers away from the trunk of the tree to prevent it from burning.
Leaf analysis is another good way to tell what your trees may be lacking. It helps diagnose deficiencies so you can treat them effectively.
Pistachio trees grow best when the soil pH is between 7 and 7.5.
Once trees are well established and producing heavy nut crops, many farmers only feed their trees once every few years and, in some cases, not at all, with no apparent reduction in harvest.
It may seem strange, as most trees don’t really require watering in the winter, but although a mature pistachio tree is very drought tolerant in summer, they do require deep watering in the winter to help them recover. We will look at this in more detail later.
Pistachio trees are either male or female, and you need one of each for pollination to successfully occur. Commercial growers will often plant their trees in a particular pattern with a particular number of female trees to every male. This helps with successful wind pollination.
If your soil is poor, you can plant trees closer together, 12 to 15 feet apart. In better soils, the tree’s spread will be greater, and space of 20 feet or more will be required.
Commercial orchards often plant trees closer together for their early years to increase their per acre nut yield. They will then cut down every other line when the trees are maturing to make more space.
This can seem like an unnecessary sacrifice, but it is all about producing the highest possible yields.
If you buy a young tree from a nursery, they usually come in biodegradable containers. Rather than remove this, you simply place it in the hole. This is because pistachios hate root disturbance, and it can kill your tree.
Grafting and Pruning
Once rootstock is potted up, it is grown to around 18 inches with a good diameter of trunk. In the fall, it will be grafted with an excellent nut-producing cultivar. The T-budding method is a widespread grafting technique for pistachios.
As they grow, they require plenty of water until they become well established.
It is common to grow them in a vase shape in California, but this should not be done in harsher desert areas like Arizona or New Mexico. A single leader is needed in these areas to prevent the tree from breaking when it’s carrying a nut harvest.
In the first few years, an open framework of branches should be established with careful pruning. Once this has been done, no further pruning will be required except to cut out dead, damaged, or diseased wood and to remove excess growth.
When pistachio trees begin fruiting, they can be harvested once the hulls start to separate easily from the nuts.
The harvest period is short and the nuts must be gathered within a seven to ten-day window, or the nuts will over ripen and become stained.
Ripe pistachios fall easily from the tree. To aid this, the trees are often shaken using a mechanical shaker. A sheet or specialist capture equipment that resembles a giant upside-down umbrella is used to collect them.
If the nuts are to be shelled and cured, this should be done on the same day they are harvested to avoid staining.
Mature pistachio trees often become biennial producers, only giving a heavy crop every other year.
Pests & Disease
In California, Wilt (Verticillium) is becoming more of a problem, not only for commercial growers but for home growers too. To avoid this, growing trees grafted onto P. Integerrima rootstock is beneficial, as it is resistant to the disease.
In this video, you will discover a whole lot more about the pistachio. Did you realize it’s actually a stone fruit and not a nut at all?
Do Pistachio Trees Need A Pollinator?
Pistachio trees are not self-pollinating. There are male and female trees, and you will require both to get nuts.
The pollen from the flowers of the male tree is blown by the wind onto female flowers. For this reason, having the trees fairly close together gets the best results.
Partner growing is popular in domestic situations where a male and female tree are grown right next to one another. For small orchards, a ratio of one male tree for every five to eight females is quite common. The male trees are then dispersed equally among the females.
For larger-scale farming where there are in excess of 600 trees, you will only need one male for every 20 to 25 females.
How Much Water Does A Pistachio Tree Need?
Pistachios come from places where summer temperatures are hot and dry. This means they are very drought tolerant. However, when nuts are filling in mid-summer, giving the trees a very deep watering once or twice a week will be beneficial.
Excessive summer watering can hinder nut production by encouraging an excess of vegetative growth.
Commercial orchards provide a drip irrigation system of 44 inches of water, laid out around the tree’s root areas.
In winter, continue to water deeply a few times, as this will help your trees recover from the stresses of summer.
How Many Pistachio Trees Per Acre?
As previously mentioned, space between trees depends a lot on how fertile your soil is. For good soils that contain high nutrient values, trees must be a minimum of 20 feet apart.
In poorer soils, planting them closer together is acceptable, but be aware that you don’t want your mature trees to be overcrowded as this will reduce the quantity and quality of nuts. It also makes pruning and harvesting a lot more difficult.
As a rule of thumb, you will be able to plant approximately 100 to 130 trees to an acre. Although if going with the higher number, thinning will often be required as the trees mature.
What Is The Lifespan Of A Pistachio Tree?
A pistachio tree can be very long-lived and can reach an age of around 300 years, although growing conditions would need to be pretty perfect.
Can You Eat Pistachio Straight From The Tree?
Yes, you can eat pistachio nuts straight from the tree. There is, however, a small risk of salmonella infection from eating raw nuts. It is better to wash them thoroughly first and ensure you have clean hands before you hull the nuts and eat them.
It’s possibly better to preserve them, although care must be taken when doing this to avoid Aflatoxin, which is a cancerous mold.
How to Preserve Pistachios
Because fresh pistachio nuts need harvesting and eating quickly, preserving them increases their shelf life.
Shortly after the nuts have been picked, remove their fleshy hull. Allow them to dry out in the sun first, as this will help make the job easier. This is necessary to prevent the nuts from becoming stained. Wearing gloves is advisable to stop the juices from staining your hands.
Once hulled, the nuts can be sorted. Separate the nuts that are split from those that aren’t.
Preservation only works if the nuts are dry enough. When picked, they can hold 10% to 20% moisture. You want to get it down to 5% or less. Not doing so means the nuts may mold, which causes a health risk.
Using the sun is the best way of doing this, providing it is warm enough. A good method is to spread them out on black plastic and cover them with a mesh screen. This prevents birds from taking them and fouling the nuts.
It’s easy to tell when they are ready. Rather than being chewy, they become crunchy. Once dry, place them into airtight containers to maintain their dryness.
You now have two options, either to leave them as they are, or to roast and salt them. If you want to use them for cooking purposes, keep them as simple uncooked, dried nuts.
5. Dry Roasting
To roast and salt them, you need to:
- Make some salt-water solution (brine). Fill a shallow bowl with about an inch of water and keep adding salt until no more will dissolve.
- Dunk the nuts in batches in the brine. I do this using a strainer to make it easy.
- Spread the brined nuts out onto a baking sheet and put them in a pre-warmed oven heated to 200°F for 25 to 30 minutes.
- Check them first after 15 minutes and stir them around a bit, then again, every 5 minutes, until they are totally dry but not starting to look browned or burned.
The roasted nuts will need storing in a clean, dry, high-quality airtight container. They stay good for a couple of months like this. If you want to prolong their shelf life further, you can freeze them, as this will slow oxidation and keep them tasting fresh.
Caring for a pistachio tree is very much like caring for any other fruit or nut tree they require:
- Planting in a suitable location with enough space around them
- Deep, sandy loam soil
- Sufficient deep watering
- Feeding of the required nutrients for good growth, leaf and fruit production
- A dry, hot summer climate
- A cool, dry winter climate
- Pruning to establish shape and then occasionally for maintenance