What temperate trees can be re-potted because of and during summer dormancy???
Chojubai and ficus can be repotted in summer not because they are dormant but because they are active. Did you have some varieties in mind?
Mostly the Mugo pine.
But I have also noticed that many of my temperate shohin trees are looking week. I checked the roots and even when watered well they are dry so I started submerging them in water. This helped on a few but I lost an 8" dawn redwood. If the trees look week would it be better to transplant them in a better draining soil or would transplanting be detrimental. Most of my soil used in shohin have about 50 percent sphagnum moss and the moss was dry when checked.
Thanks Paul. That was a good idea to check the soil more carefully - old or poor soil can make watering tricky. One strategy is to remove the top 1/2 - 1" of soil and replace it with new soil (http://bonsaitonight.com/2010/08/27/summer-soji/). When I do this I also use a metal chopstick to create holes that reach through the rootball to make sure water gets to the roots when I water. I’d start with this approach.
The other option is a light repotting. I’d hesitate to do a standard repot on a mugo pine this time of year, though a light repotting can work out if the roots aren’t disturbed too much. I’ve found this option can also be tricky if the original rootball repels water. By adding new soil around the edge of the pot this make it easy for water to bypass the part of the rootball that most needs it. The trick is doing enough rootwork to ensure the roots get water but not so much as to weaken or kill the tree.
Thanks for the info. I also have some good news. The dead 8" dawn redwood was planted in the ground about 10 days ago and today specs of green are on the trunk. Hope it can recover enough to make it thru the winter. It will be kept in the ground and heavily mulched this winter.
I have seen totally dormant Aesculus californica, California Buckeye, bare rooted and root pruned in late July or August.
Vance Wood recommends root work on mugos during the Summer dormancy period but bear in mind he’s from Michigan I believe where the temps are cooler.
Dawn Redwood are very thirsty. If additional shading isn’t practical I’d up your organics. Similar to swamp cypress I’d say it’s very hard to over water this tree in an arid environment.