A few weeks into summer (after the summer solstice, which was yesterday) through early fall, one can repot just about any conifer as well as waxy broad leaved plants such as rhododendrons, azaleas, chaenomeles, cotoneaster, pyracantha, ilex, ulmus, zelkova, rose, most quercus, most magnolias, can as well. A secondary rule is to not repot when new growth is extending.
The risk, of course, is that the plant desiccates before the roots can recover from the damage done to them by repotting. Generally, all these species do a very good job of limiting water losses by closing their leaf stomata because of their waxy leaf coatings. So you put these right back into full sun or the sun exposure where you had them, because photosynthesis is required to grow roots = recover from repotting damage.
Non-waxy broad leafed plants such as maples and redbuds, loose lots of water through their leaf surfaces, so the risks of loosing the plant are far higher. The only way to reduce water loss is to increase the relative humidity at the leaf surface, which generally means shade and sprinkling/misting. It can be done, but with great care. If you are daring,
I suggest you buy a number of these plants when they are inexpensive enough that you can afford (financially and emotionally) to loose them and have the time to play close attention to them for at least the 7 to 10 days following repotting. You've got to do it to know how to do it.
