On field trips to John Panzarella's and at Devine Avocados, I had seen avocado and citrus trees that had escaped their pots, and taken root in the surrounding native soil. Hoping my trees might do the same, I sneakily cut some holes in the bottoms of the pots when I planted the trees, and buried the pots an inch or two into the ground. Well, It's been almost two years since I planted those trees (Brazos Belle and Poncho), and in that time they've grown like crazy. They really took off when I hooked them up to the automatic drip system in my greenhouse, and they started to get smaller applications of water every day instead of deep waterings once or twice a week. I knew that at this rate they would soon outgrow their 30-gallon pots, and that if I wanted their roots to escape to the freedom of the native soil, I would have to help break them out.
First, Boy #1 and I took a little side trip to a place I know with lots of good sandy topsoil, and dug and dug until we had 12 5-gallon buckets full of dirt. We hauled it all home and lugged it to the back yard. I pulled back all the mulch and pine needles from around the pots, and did my best to rough up the soil around them. Then using a sharp utility knife, I cut square holes approximately 3-inches by 3-inches all the way around the bottom of the pots. Healthy bright-white roots were clearly visible encircling the pots, and I did my best not to slice them as I cut the plastic. I also tried to loosen up the soil and gently tease out the roots out of the holes using a garden hose and my fingers.
Once the holes were cut, Boy #1 and I began banking the sandy topsoil around the pots; six buckets of soil for each tree. As we worked, we mixed the topsoil with MicroLife 6-2-4, composted kitchen scraps, and a little humate to help encourage the avocado roots to escape. The 30 gallons of topsoil we placed around each tree resulted in a nice donut-shaped raised bed around each pot, approximately 6-inches deep and a foot or so wide. Finally, we covered the topsoil with several inches of leaves and pine needles, and watered it down. Hopefully, as fertilizer and water from the drip system drain out of the new holes and into the banked topsoil, the roots will follow and eventually take hold in the native soil.