Melvin Wei's video: Growing Joshua Trees from Seeds Years 3 7-4 2

I've been dreading this day for a long time, the day I would have to transplant my Joshua tree. I kept it in its existing pot but raised the root ball by about an inch above the slits above the watering tray so as to give the roots more room to grow downwards. The roots of the Joshua tree bear a striking resemblance to those of the mango tree, and like the mango, want to grow deep, not laterally as some people say. I decided to do this equal volume transplant into the same pot but with real dirt to get the root system out of potting mix. Potting mix, which has ground up tree bark and things like sphagnum peat moss in it, can take much longer than just 4 years to completely break down into nothingness. The constant decay of potting mix robs the roots of the oxygen they need to thrive. Rotting organic matter also releases toxic gases that will poison the roots of plants. My Joshua tree survived this long because it had most of its large roots at the bottom where the roots could freely breathe oxygen, and it seems like this species can thrive even in low oxygen soils such as the hard clay soils of most of Joshua Tree National Park. All of my other plants tended to perish within days, weeks, or months of living in potting mix, or didn't do well. It's no coincidence that all of the plants that I've transplanted into sandy soil have done really well since, whereas the plants still in potting mix are still sickly and need rescuing. This transplant took almost an entire Saturday's worth of work to accomplish. I was exhausted. The bottom line is I didn't transplant to a bigger pot because I didn't have one ready, and I didn't want to go dig up close to 100 pounds of real dirt and haul it from my car all the way to my apartment balcony. Although my Joshua tree has some thick roots, I believe a lot more growth can occur as is with this new sand and sandy loam mixture.