Answer: The traditional best times to plant are very early spring and in the early fall. The reson for this is that the plants can root during a cooler gentler season when natural rainfall tends to be plentiful. (An exception to this is broad leafed evergreens which are best planted in the spring, the reason here being that they lose moisture all winter through their foliage and it is sometimes difficult to keep them hydrated.) However, with container grown plants, in my experience it is usually better to plant them right away rather than try to keep them in the pots under home conditions for nay length of time.
Take care to water them as needed to keep the soil evenly moist but not sopping wet while they root. You will need to use your finger and check both the potting mix and the surrounding soil because the potting mix will usually dry out faster. Use several inches of organic mulch over the root areas (do not put it against the stems however.)
Also, since it is August and they are going into what would be considered full sun, if you can shade them somewhat during the hottest part of the day for the first few days, that can help reduce the transplant shock as well.
Finally, keep checking the soil moisture through the fall until the ground freezes, and continue to do so again next summer.
Good luck with your new plants.
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