I bought a few nursery trees that I want to pot in much larger pots. Is it alright to repot these trees if I’m not planning on messing with the roots, other than loosening the dirt around the roots?
Are you in the northern hemisphere or Southern Hemisphere? Why do you want to put them into larger pots?
I’m in Montana. Beginning of fall here. They are going to be parent plants and they are in smaller nursery pots. I want to prepare them for the harsh montana winters even if they are going in the garage.
Slip potting should be safe this time of year. The biggest downside is that you give up the opportunity for root work and improvement. If you plan for it to be only a parent plant for cuttings or layers thats not as big of a downside though.
Its also important not to go too much bigger on the pot, but a gentle slip into a little larger pot should be safe in my opinion.
Yeah if you go too big too soon, you run the risk of overwatering. As long as you realize the tree doesn’t have roots out at the edge right away, you should be able to water appropriately.
I suggest that you loosen the outer portion of the root ball as you described so that you do not have a huge change in the soil from the current root ball to the new soil. For a tree like this I have found that doubling the volume of the soil is about right which means that it looks like you only increased the pot size a little.
If you want to help mitigate temperature swings in the garage, I suggest placing the new pot in one that is 4-5 times the volume and filling with garden soil once you get leaf drop and it is time to reduce watering. That soil can be wetted which will really help with the temperature swings while not keeping the soil around the roots too wet. My climate is a bit milder so I have used the ground as the soil around the new pot when slip potting a fall acquisition that is very root bound.