These are the rules of thumb that I try to keep in mind for watering fruit trees during late spring, summer, and early fall (think May or June into October):

If the fruit tree is two feet wide (about as wide as your body), then give it two gallons each week.

If the fruit tree is five feet wide (about as wide as your wingspan), then give it ten gallons each week.

If the fruit tree is ten feet wide (about as wide as a driveway), then give it fifty gallons each week.

If the fruit tree is fifteen feet wide (about as wide as the door of a two-car garage), then give it one hundred gallons each week.

This is a great place to start

Now, there are a million reasons why those numbers won’t be perfectly accurate for a particular fruit tree in your yard. There are a million reasons that different fruit trees growing in different parts of even a single yard — let alone different pockets of Southern California — need to be given different amounts of water in order to be healthy and produce lots of quality fruit. But they are a reliable place to start, in my experience.

If you are wondering how much water to give a particular fruit tree, place it within the above size category and give it that approximate number of gallons each week.

A couple of examples

For example, here is a Satsuma mandarin tree that is not quite as wide as my outstretched arms — I’d guess four feet wide.

Satsuma mandarin tree plus a melon vine on the ground below.

How much water should I give it? The rules of thumb say around eight gallons each week. I would start there and see how the tree looks and how the soil feels going forward. It so happens that I actually give this tree somewhat more, which satisfies the thirst of that melon vine I planted beneath it.

Another example: here is a Snow Queen nectarine tree that is wider than my wingspan but not quite as wide as a driveway. I’ll say eight or nine feet wide.

Snow Queen nectarine tree.

So maybe it needs around 35 gallons of water each week according to the rules of thumb above.

Let me tell you, however, that I only give this tree about 25 gallons of water each week and it does great. Every tree is different, and you get to know what your tree really needs by starting somewhere (the rules of thumb) and then evaluating and adjusting as the tree’s foliage and soil give you feedback. (For more on this, please see my post “Get your hands dirty: Discover the truth about your irrigation practices.”)

Snow Queen nectarines, getting bigger every day here in June.

Notes on the rules of thumb

This is not to say that you need to water once each week. You might water once a week, twice a week, or every two weeks. Often, it doesn’t matter much, especially with older trees. Anyway, that’s a separate topic. (And a good one for a future post!)

Also, remember that a fruit tree doesn’t need this much all year long. These amounts are mostly accurate for the warm months of May or June into October. During the cool months of October or November through winter and on into May, the fruit tree will need less. Often, a fruit tree needs no irrigation water at all from December through March because of the cool temperatures and sufficient rainfall.

How much water is your sprinkler applying?

If you are using a micro-sprinkler or sprayer on a fruit tree and you don’t know its output, you can stick it into a bucket for ten minutes and then measure how much water it put into the bucket. Multiplying this amount by six gives you a gallons-per-hour rating.

For example, the other day I measured that a sprayer on a young avocado tree put out about 0.75 gallons in ten minutes, which is about 4.5 gallons per hour.

The tree is just under five feet wide, so if I want to give it around ten gallons per week, then I need to run the sprayer for about two hours per week.

Again, the rules of thumb for how much to water fruit trees:

If the fruit tree is two feet wide (about as wide as your body), then give it two gallons each week.

If the fruit tree is five feet wide (about as wide as your wingspan), then give it ten gallons each week.

If the fruit tree is ten feet wide (about as wide as a driveway), then give it fifty gallons each week.

If the fruit tree is fifteen feet wide (about as wide as the door of a two-car garage), then give it one hundred gallons each week.

That’s 2 feet, 2 gallons; 5 feet, 10 gallons; 10 feet, 50 gallons; and 15 feet, 100 gallons — each summer week. Is your watering volume close to this? It doesn’t have to be, but if you’re feeling unmoored and unsure of where to start, then start here.

Other posts about watering fruit trees:

Setting up micro-sprinklers under fruit trees

How much and how often to water avocado trees in California

Keep mulch away from tree trunks?

What is the best time of day to water your plants?

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