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Monday, June 20, 2011

Is Twenty Minutes Enough Water for an Olive Tree?

Q. My fruitless olive tree is losing leaves branches on the south side of the tree. It has been in the ground since December 2010 having been planted from a 36" box. I have been watering it 3 times a week for 20 minutes each time since March, less frequently the past winter.
It has 4 emitters. Since I noticed the bare branches, I have started to hand water once a week for an hour with a bubbler. The wind usually blows through the tree from the south where the bare branches are located.

Drip emitters
are measured in gallons per hour
A. Let’s assume your drip emitters are three gallons per hour, a very common rate for drip emitters which are not adjustable. You have four of them. That makes 12 gallons per hour. You water for 20 minutes that means you water the olive with four gallons.

To fill a 36 inch boxed tree with soil I would guess would take about 25 to 30 gallons or more. This tree is way underwatered. Run the hose on the tree in a four inch deep basin surrounding the planting hole and fill the basin twice every time you water. This tree will require somewhere around 30 gallons or more each time you water.

You will need to add emitters to the tree or run the drip for at least 2 to 3 hours each time you water as it is presently configured. Right now you should be watering twice a week with that volume.

I want to add that if you are planting trees and shrubs you should ALWAYS hand water them in for two to three weeks after planting and then begin your drip system. Do not just turn them over to drip irrigation after planting.


  1. You do not address the issue of the fruit - the olives. traditional knowledge in the Middle East says olive trees should not be watered at all, as it spoils the fruit, but should thrive on what the soil absorbs during the rainy season. If over-watered, the olives fill up with water and don’t develop oil.
    While not a professional, I’ve observed this to be true when friends have planted olive trees in their garden and then get useless watery olives as a result of standard garden watering. Your opinion?

    1. Thank you for your post. Here in the Mojave Desert we receive on the average only 10 cm (4 inches) of rain each year. We have had as much as 18 months of no rain here. Olive trees will not survive here without applied water to the soil, usually using drip irrigation. Sprinkler irrigation that lands on the fruit is wasteful and can spoil the fruit when ripe as well as dates which we can grow here very successfully. One olive poroducer...for oil... is applying too much water to his trees with drip irrigation and the fruit/oil has too much water which lowers its quality. The trick is to produce fruit with high oil content and low water content which means to irrigate very carefully and not apply too much water. Most homeowners here in the US want an olive tree for its beauty and not for production of olives. In fact, we are required to purchase and plant only olive trees which produce very few olives because of the allergies produced by these trees due to pollen. In Lebanon, Italy and Sicily these trees survive on rain fed water mostly during the winter months with dry summers..perfect for olives. A Mediterranean climate. Ours is a desert climate so we must irrigate. We irrigate for tree beauty, not for olive production.