The skill of grafting empowers you. Being able to graft gives you options. Nursery doesn’t have a Sharwil tree for sale? If you can get your hands on a Sharwil scion, then you can make your own. Just moved into a house with a big avocado tree that makes inferior fruit? Cut it back and graft it over to your variety of choice, and you’ll have a big tree full of your favorite avocados in only a couple years.
My aim in this post is twofold: to connect you to the best resources about grafting avocados, and to share tips in areas where I’ve made mistakes over the years.
1. Best resources
There is one book about grafting avocados: “Propagating Avocados: Principles and Techniques of Nursery and Field Grafting” by Whitsell, Martin, Bergh, Lypps, and Brokaw.
“Propagating Avocados” has many excellent photographs and drawings, and I reread it a couple times every year. It was written by a group of people with vast experience on the subject.
A web search for videos on grafting avocados turns up many results. I’ve watched a good portion of them. There are a handful that are worth your time. Here are three that are most worthy of your time.
Gray Martin is one of the authors of “Propagating Avocados,” and he has made a series of videos about grafting avocados, specifically on topworking (changing a big tree over to a new variety).
(Martin also wrote this provocative article with Bob Bergh: “Avocado Topworking Update 1990.”)
Ty McDonald slowly and clearly walks you through how to do a side graft on a young seedling avocado tree. In Ty McDonald 1, he talks about why we graft, tools to use, and methods to choose from. In Ty McDonald 2, he performs a side graft to transform a seedling into a Sharwil.
To see how tip grafting is done on very small seedlings in a commercial greenhouse setting, this video about Lynwood Nursery in New Zealand is worth watching. You’ll see things that will help you do your own tip grafting at home.
2. Notes on grafting avocados
The first time I wrapped a scion with Parafilm, an old timer named Jim Neitzel was guiding me. I had wrapped too thickly. Ideally, Neitzel pointed out, you want only one thin layer of Parafilm over each bud. This way the moisture stays in, but the bud also has no problem breaking through the Parafilm as it grows out. That lesson has stuck with me and yielded good grafting results in the years since. Only one layer of Parafilm over a bud.
When tip-grafting small trees in containers, it is not necessary to keep the newly grafted tree in the sunshine. In fact, unless it is winter and the sun is very weak, it is far safer to keep the newly grafted tree in some amount of shade until the graft has healed and the scion has grown out a few inches.
This should especially be kept in mind in summer. Keep newly grafted trees out of the strong sun until they have grown leaves to shade their stems and trunk.
I have grafted successfully during 100-degree days in August through keeping the newly grafted tree in shade.
Best time of year to graft
March is usually the magic month in Southern California. Why do avocado grafts do well at that time? It has warmed up a little and trees have started to grow. February can also be a very good month, as can early April — it depends on the year’s weather.
But this is for grafts done outside. If you use a greenhouse or a shade structure, then time of year doesn’t matter nearly as much.
Best time of year to collect avocado scions
March is not always the best time to collect avocado budwood though. It is sometimes better to collect scions earlier.
The best avocado budwood has plump and green buds which are still dormant. You can often find such budwood on any given day of the year, but it is usually most plentiful in the winter after trees have paused growing and before they resume growing.
If a tree has good budwood for the taking but the stock you want to graft onto is not ready, you can store the scions in the fridge for at least a month, sometimes many months, without their losing viability.
How long should avocado scions be? Many people use sticks that are about six inches long, but I tend to use shorter ones. If a scion has two good buds, I’m happy and get fine results.
Curiously, back in 1960 some researchers found that scions closer to six inches had better take compared to scions about three inches long. See the discussion about scion length (and time of year to collect) in “Some Factors Influencing Grafting Success with Avocados” by Rodrigues, Ryan, and Frolich. Despite this finding, I continue to use mostly shorter scions, but maybe I’m a fool.
Storing avocado budwood
To get the most life from an avocado scion, you want to keep it cool and to prevent it from drying. Placing the stick in a plastic bag, and placing the bag in the fridge works perfectly.
Some people put damp paper towels or newspaper into the bag. That’s not necessary even though it’s also not harmful unless the paper towel or newspaper is too wet. The plastic bag alone keeps the scion from drying out. My preferred plastic bag is a one-gallon Ziploc.
At its heart, grafting is simply connecting the extremely narrow cambium layer of one branch to that of another. Yet over time people have come up with an array of methods to do this. You choose a method based on the size of the scion, the size of the stock, the time of year, and many other factors. See the “Propagating Avocados” book mentioned above for help in choosing a method.
Here is a short video that I made comparing two methods that I use often:
May there be magic in your finger tips this grafting season.
You might be interested in this post: “Where to get avocado scion wood”
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