My favorite time to plant avocado trees is March; my second favorite is October. So I might be planting some this month, and you might want to, too. Then what? How to water the new tree?
In the last handful of years I have established most of my newly planted avocado trees on drip irrigation. I wouldn’t say it’s the best way for everyone, but it has been simple and effective for me, and I’ve seen it work well in many other yards and on many farms.
I’ll show you a few key aspects to my current method, used in my yard. I’ll also show you a few variations used on farms, noting their pros and cons.
My best results have come from using three emitters to water a newly planted avocado tree.
I place one emitter right next to the trunk because that is where the roots are on a newly planted tree. This emitter is absolutely necessary. Then I place an emitter on either side, spaced six to 18 inches from the trunk. (The spacing within that range hasn’t appeared to make a difference in my experience.)
The two side emitters serve two functions. One, they allow the tree’s roots to expand because they wet soil beyond where the roots are at planting. (Roots will only grow in soil that has moisture.) Two, they give the baby tree some resiliency to competition from big plants nearby. In a yard situation, there is often an older tree or other established plant close enough to grow roots into the zone where the baby avocado is being irrigated. That older plant will rapidly start to drink the water given to the avocado. But I’ve noticed that when I expand the irrigated zone around the baby avocado, as with the three emitters, it withstands the root competition better than if I only give more water volume through one or two emitters.
If you’re lucky, your newly planted avocado tree will grow fast. The bigger it gets, the more water it needs. You can run the system for longer, but eventually the tree will need additional emitters.
My favorite way to plan for this is to include extra drip tubing at the time of planting, from the beginning. So instead of just using enough tubing for three emitters, I leave it long enough to have five or six.
At planting, the tubing can be folded to only allow three emitters to run. Later, as necessary, the tubing can be unfolded to allow more emitters to run. This is easier than using an adapter to connect more tubing.
Have a look at this video showing an example with a tree I planted this spring:
If you have more than a couple trees or a full farm, you’ll probably want to use a different layout. You’ll likely plant your trees in rows, and you’ll run a single tube down the entire row.
Here is an example of trees at Cal Poly San Luis Obispo started on a single line of drip irrigation:
These trees all had three emitters placed under them at planting time, just as I do in my yard.
The emitters under the Cal Poly trees were punched into the tube, but you can alternatively put in spaghetti tubes that have button emitters on the ends:
One advantage of this is that you can move the emitters away from the trunk as the tree gets bigger and its roots reach farther.
Drip tube with inline emitters
Another way to start trees on drip in a farm situation is with tubing that already has emitters built in, called “inline” emitters. The emitters can be placed every 12 inches or 18 inches or other spacings. With inline drip tubing, you just lay a single tube down the row next to the trunks of the young trees.
But some farmers choose to use double driplines, two tubes, in which case they’ll likely never need to add any more tubes or emitters as the trees get bigger.
Here is an example of double driplines with inline emitters on a newly planted avocado tree:
The downside of using inline emitters (single or double) is that you waste some water in the first year or two since the young trees’ roots haven’t yet reached the dirt being wet down the row in between the trees. A way of mitigating this is to plant something else between the trees, just for the first year or two. I’ve seen growers plant pumpkins, melons, and cover crop mixes with oats and peas to make use of those emitters.
More to think about
What about how long to run the drip system on newly planted avocado trees? Which emitters are best — 0.5 gallons per hour, 2 gallons per hour, etc? Should you cover the driplines with mulch? How do you expand the drip system as the trees get bigger? Is drip as good as sprinklers for avocados anyway? Even better?
I have answered some of these questions in other posts. See:
I will answer others in upcoming posts.
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