I read on a regular basis that the best time to repot, including root pruning is in the late winter or early spring. I have a few questions on the reason for such timing, and I wonder if a Mediterranean climate is an exception due to the opposite advise being common for non-bonsai.

I live near Sacramento CA with long hot dry summers and wet winters that almost never go below 30 deg F. When landscaping I am often told to plant trees, shrubs, grass, and perennials in the fall so that they can establish a root system over the course of our mild wet winter, leading to strong growth in the spring.

Please note that in winter a lot of plants never stop growing here, or have begun regrowth as early as January.

Is it true that plants focus on developing a strong root system in the fall and winter? Does this translate to a general benefit to fall repotting in my climate? (obviously species characteristics and specimen health are critical factors).

It seems like weakening the root system before a long hot dry summer is dangerous for me and makes it more difficult for the plant to stay hydrated (our primary challenge. Fungus and rot are rare out here)

Also note, I am fairly new and all of my trees are young and need to grow grow grow. I am not worried about reducing leaves or refining trees. I am seeking monster growth at this point.

If you want maximum growth, you should not be worrying about repotting. You should let the plants grow

As for spring repotting.. I am not sure. I have always heard about fall planting for landscape plants here too. The window oktober, november being heralded as ideal. With bonsai, repotting goes hand in hand with massive root reductions. If you do not have enough time for the wounds to be sealed and new roots to start when the plant enters dormancy this may increase the risk of infections. But as you say you do not have this..

I still think (!) that even though you do not get frost, you get a spring spurt of growth. This is the period where I would say roots recover best from insult.

Best way to be sure.. Try both. Get a few young plants. In fall repot a bunch. And in spring repot the other half. Then see which do best.

leatherback wrote: If you want maximum growth, you should not be worrying about repotting. You should let the plants grow

Now that I think about it I’m only slip potting, so timing is probably not as important as getting them into a decent pot or in the ground so that they can grow.

Yes, springtime is much more growth than the rest of the year, so I will keep that in mind for heavy root work.

Now that you have me thinking about it, the landscaping advice is geared toward plants going from nursery pots and being “slip potted” into the ground, usually with root disturbance minimized. Root work probably requires springtime conditions for a rapid recovery from the weakened state.

Maybe I will not reinvent the wheel.

Thanks!