This week at ECHO North America we are going to start grafting Avocado (Persea americana), which is one of my favorite species to graft. Check out this time lapse video to see the whole process from seed to sell-able grafted tree! Avocado Grafting Time Lapse | ECHOcommunity.org.
We start every grafting session by selecting good budwood. Check out this post on what makes good or bad budwood Avocado (Persea americana) - Budwood Selection.
The next key factor for successful Avocado grafting is rootstock selection. We graft onto very young rootstock. It is still purple stemmed and VERY flexible. In the photo below you can see the ideal rootstock stage circled in red; small, but still acceptable rootstock circled in yellow; and circled in blue rootstock that is starting to be past it’s grafting prime, it could still be grafted if needed, especially if you have very thick budwood.
For additional information on how to plant Avocado seeds for rootstock use see this post Avocado (Persea americana) - Seeds for Rootstock.
Next step is selecting an avocado rootstock that is the same diameter as your budwood or at least a very close match. For these micro grafts we make our cuts within 5 inches of the seed/soil level. Avocados produce aggressive rootstock sprouts when healing so the lower graft union allows for less rootstock sprouts to manage. When we make the first cut to remove the top of the rootstock we do not leave any leaves below the graft union. The robust seed keeps the young rootstock alive during the quick healing process for avocado. Next we quickly make a clean cut 1.5 in straight down the center of the stem. If your diameters do not quite match up you can shift your cut off center to make a better match.
On our budwood we make two cuts about 1.5in long, one on each side of the base. The result is a nice V shape with a fine point (circled in red below). We have found that if the cuts are too short and the angle is too wide then the budwood will be prone to shooting out of the graft union while you are tying it together with the rubber band.
Quickly slide the prepared budwood down into the slit created on the rootstock and secure it with a rubber band or grafting plastic tape. They key here is a tight graft union, which can be initally challenging to achieve because the young plant material is very slippery. If a graft union is particularly challenging a cheating tip is to take a small piece of parafilm and secure it first with that and then wrap the rubber band from the scion down to the rootstock. Once the graft union is secured wrap the entire graft union and scion in parafilm. We always make sure to label our grafts (Species - Variety - Date - Grafter - Comment) so that months later we know what we have.
The final step is to place the graft back on the table to heal. Avocado grafts tend to take only a few weeks to push new growth and demonstrate success. If the graft fails then cut off the stem with the graft union and allow the seed to push a new shoot and try again!
