Back in February of this year we planted a Haas Avocado in this spot and a Stewart at the bottom of the yard. Everything was going pretty well for the tree at the bottom of the of the yard but the one up here was struggling. Then in late September we had the hottest day on record in Los Angeles and neither tree recovered.
Even though the heat is what finally killed the trees I think our poorly draining soil was responsible for their limited success to that point. If they had grown more vigorously prior to the heat wave they may have been big enough to survive. This time I created a truly ramshackle 18 inch retaining wall using a technique that was influenced by gabion walls. It was made using only materials we had on hand in about half a day.
This time we went with a Zutano at the top of the hill and put another Haas at the bottom. I expanded the previous efforts to amend the soil and ensure that the drainage is as good as it can be.
At the top of the hill I built a retaining wall to hold in a much larger quantity of amended soil. I reused some of the T-posts we were no longer using to hold up the concrete reinforcing wire fence that Phoenix replaced with wood a few weeks ago. I doubled up some chicken wire and ran that inside of a scrap piece of galvanized wire fence. The doubled up chicken wire helps hold in some of the smaller rocks that would pass through the thicker wire fence otherwise. Then I filled the space with rocks, broken cement pieces and bricks.
Carting the rocks up that steep hill was a pain in the neck. I'll add another course when I recover. I back filled the wall with home made potting soil made with our compost, perlite, gypsum and some organic fertilizer formulated for avocados. It's almost like a raised bed now and I hope it will drain better this time.
So far the tree looks pretty happy and the wall looks good enough from the distance that most people will see it. I'll add another row of rocks and more soil mixture in a week or so and keep my fingers crossed.