(Last updated June 1, 2020)
Even though I’ve planted many avocado trees, I was nervous putting in this little Jan Boyce, or JB for short (pictured on left). It is a particularly fine-tasting variety that I’d been trying to get my hands on for years.
But I needn’t be too nervous. I’ve already made most every mistake there is when planting an avocado tree; I know what not to do anymore. So here I write about how to plant an avocado tree with an eye toward avoiding common errors.
Testing soil drainage
How fast water drains through the soil in your yard is a vital piece of information to know because avocado trees are unlike any other in that they have a very low tolerance for their roots remaining soggy.
So what you should do before planting in a spot is test the drainage. You simply dig a hole about a foot deep and a foot wide, fill it with water and wait for it to disappear. Then fill it again and see how long it takes for the water to disappear this second time.
A rule of thumb that many avocado experts have used over the years is that it must disappear in less than a day, 24 hours. But really, if it takes more than about eight hours I think you’re in the danger zone and you’re going to have to be careful not to water too much too often. Otherwise, your tree’s roots will rot, its leaves will turn yellow and droopy, and you’ll have wasted your time. It probably won’t be apparent right away. It might not reveal itself until the end of summer or until the tree’s first winter.
Mounds can help. If your spot’s drainage is on the slow side, then build a mound of soil from 1-3 feet high and 4-7 feet wide and plant the tree in the top of it. You’ve essentially created an area of soil with better drainage for your tree.
A friend slowly killed three avocado trees in his slowly draining soil before I helped him plant a new tree on this mound:
It has been a year since that planting, and the tree continues to grow well.
On the other hand, if you have fast-draining soil like me, where water drains out of the hole in less than an hour, then don’t bother planting on a high mound. If you did, you’d make it necessary to water even more frequently. In our case, plant level or only raised a few inches — unless your soil is shallow. If you hit rock or gritty subsoil only a foot down, do plant on a slight mound just to give the tree more good soil to root into.
Getting the avocado tree from container into ground
How to put an avocado tree into the ground? Dig a hole that is about twice as wide as the container. Do this so you can get your hands in the hole as you lower the tree and settle it in. There’s no need and no benefit of making the hole any wider.
Also, dig the hole only as deep as the soil is in the container, no deeper. Don’t even dig the hole as deep as the rim of the container; only dig as deep as the soil within the container. If you dig deeper, you’re wasting energy at best.
To get the tree out of the container there are different techniques according to the size of the container. A little one-gallon like my Jan Boyce is easy. You just squeeze the sides a bit to separate the plastic from the roots, then tip the container and slide the rootball out.
Do this right next to the planting hole so you don’t have to carry it. Usually, the container mix is a loose mix and the avocado roots don’t hold it together well. The rootball tends to fall apart in your hands. So lower it right into the hole immediately.
Avocado roots are brittle. They’re unlike other fruit tree roots. Still, if any are circling around the outside of the container mix, then very gently loosen them. They break easily, but do your best to loosen them a bit. This way they’ll extend out into the native soil from the very beginning and give the tree a larger soil volume to access.
The most common size of avocado tree that we home gardeners buy in nurseries is sold in what’s called a five-gallon container. The process is the same as for my little one-gallon container, but everything is heavier and more awkward. It can help to have a partner when sliding the container off the tree’s rootball.
The largest size that most nurseries sell is in a 15-gallon container. These trees are so big and heavy that they require a different procedure unless you’re The Hulk. What I do is cut the container off the tree’s rootball rather than slide it off. I lay the tree on its side next to the planting hole and, with a utility knife, slice down one side of the container and across the bottom. Then I roll the tree and slice up the other side. You can then pull the container off and slide the rootball into the hole. (It’s crucial to have made the hole the proper depth before sliding the tree in.)
(You might like to read my post, “Should you buy a big or small avocado tree?”)
At this point, put some of the dirt from the hole back in around the sides of the tree’s rootball, but only about half way. Then fill the moat with water. After it drains, tamp it down with your fingers to get air pockets out and settle the soil around the roots. Then fill the hole with dirt up to the level of the tree’s container mix, but don’t cover the container mix with dirt. If you do, it will be hard to get water through the dirt and into the container mix where the tree’s roots are.
Note that you’re only using your native soil to fill the hole. There’s never been any benefit shown in adding compost or fertilizer to an avocado tree’s planting hole. (You can read about an experiment making big or small holes, as well as filling with just native soil or adding compost here.)
I like to build up a berm a few inches high around the new tree now. I make it a foot or two wider than the container was, and I add mulch. The berm isn’t necessary, but it makes it really easy to water in the tree right here after planting, which is necessary.
You want to water a lot on planting day. Along with testing the drainage, watering lavishly on planting day is the second very important thing you can do for your new avocado tree.
Not only do you want to water the tree’s rootball, which has been shocked by having its home removed and being placed in new surroundings, but you also must thoroughly soak the surrounding native soil because otherwise it will literally suck the moisture out of the container mix. Real dirt is able to grab and hold onto water better than any container mix. This is also the reason that you don’t want dirt covering the top of the container mix. (See photos of water’s movement, or non-movement, between native soil and container mix in this excellent article by Dani Lightle of the University of California’s Cooperative Extension.)
I fill up the basin, let it drain, and fill it up another couple times in order to soak and settle the planting area. You could also accomplish this watering with a sprinkler.
Staking the avocado tree
My little Jan Boyce didn’t come with a stake and it doesn’t need a stake. But if you bought a five- or 15-gallon tree, there will be a stake tied to it.
You cannot remove this stake and expect your tree to stand up on its own, nor can you leave the stake as is and expect the tree to grow a strong and healthy trunk. I’ll call this the third key to getting an avocado tree off to the best possible start to life in your yard.
Some years back, I broke my ankle. I was in a cast for some months, and then I visited my doctor and he took it off and told me to stand up. I was afraid. But he explained, “As soon as possible, you need to start using these muscles again so they will strengthen.”
The stake that is tied to your new avocado tree is a cast. It supports the trunk, but it also prevents the trunk from strengthening. The trunk can only strengthen if it is able to flex.
What I usually do is replace the nursery stake with two stakes inserted just outside the rootball on either side of the trunk. The stakes can be made of bamboo, 1″ x 1″ wood, metal, it doesn’t matter. Using one-inch nursery tape or something similar in size, tie the trunk to each stake. (The tape can’t be too narrow or inflexible or else it will cut into the trunk as the trunk grows and moves in the wind.)
You want to tie the trunk to the stakes as low as you can without the trunk flopping over. If the trunk is already fairly strong, you’ll be able to tie relatively low. But if the trunk is weak, you’ll have to tie higher or even possibly tie at two levels.
Every month or so, check up on your stake ties to see that they’re still holding the tree up correctly. Often they need adjusting.
Avocado farmers usually use a slightly different method. They replace the nursery stake with a thicker, taller single stake (2″ x 2″ wood or metal pole), and the tree is tied to that. This staking method also works.
In addition to staking, you may need to do a little pruning over the first year or two in order to balance the tree’s growth and help it stand alone. I pruned some of the floppy top off this young Pinkerton tree, and it is now sturdy.
On the other hand, I was too timid to do much early pruning with the Lamb tree shown below. It is no longer staked but it continues to lean even now at five years old.
After being watered in and staked (or maybe I should say “restaked”), your baby avocado tree is ready to run. Just be aware going forward of a couple of important issues. One is sunburn. Exposed branches on avocado trees, including the trunk, are more sensitive to sunburn than any tree I know. Please read my post, “Avocado trees get sunburned — what to do?”
Also, if you’re planting in the summer, consider shading the new tree on hot afternoons for the first few weeks. By hot afternoons, I mean over 90 degrees. The reason this might be helpful is that often at nurseries trees are bunched together and shading one another, but you might buy and plant yours alone in full sun. This can add to the shock of transplanting. I’ve found that giving such a tree relief on a hot afternoon while it’s acclimating can avoid sunburned leaves during those first weeks. (See photos of shade structures in the above linked sunburn post.)
Secondly, even as watering avocados appropriately is important generally, watering avocado trees during their first one to two months requires extra attention. Once you get through this initial phase, your tree is resilient because it will have grown roots into the surrounding native soil. In the meantime, don’t slack. And for details, please read my post, “How to water a newly planted avocado tree.”
Finally, if your yard ever gets frost, be prepared to protect your young tree from any particularly strong cold spells in its first winter or two. This can be as simple as posting a beach umbrella over it for the night. For more on that see my post, “Protecting avocado trees from cold.”
You might like to watch:
A tour with Julie Frink and Tom Spellman through the University of California’s amazing avocado germplasm collection in Irvine. See a mature Jan Boyce tree, plus many other rare and common varieties.
You might also like to read my posts: