If the plants are potted I would not hesitate to plant them now, provided you can give them water for the rest of summer. Since they are in pots now, they will not really have much of a root system in the ground this summer, making them susceptible to drying out. At first it will be almost like they are in a pot, since their roots will not extend beyond the soil that came in the pot. However, they will be growing new roots, and planting them now will give them a much better start on growing than fall planting would, I think. I think for any plant, if it can survive in the pot all summer, it can survive in the ground (assuming it gets adequate care from you).

Thanks for the encouragement, I really wanted to buy those plants but didn't want to feel guilty about wasting money.How do you deal with the severely rootbound pots, though? These seem to be the rule with stuff from local nurseries. I generally slice through the circling roots on opposite sides of the root ball.

Jasonkay, if the plants are in pots, the general rule of thumb is that they can be planted anytime during the growing season. You just want to be sure that the potted plants are well-hydrated and are acclimated to their new growing conditions before planting, i.e. don't take a potted plant that is accustomed to part shade and plant it in full blazing sun without a little protection. Also be sure to water regularly and mulch, esp in the summer.

Now transplanting a plant in the ground from one location to another is a whole different story. In that case you are digging up an established plant, exposing and damaging roots, and causing a great deal more stress to the plant that simply plopping a potted plant in the ground. Although it can be done in the summer with great care, it's best to do this in spring or fall.

As for pot bound roots, I usually use my hands to uncircle and spread the roots out. If they're impossible to unwind, then slicing a bit helps. Sometimes I can be pretty rough with the roots but most plants don't seem to mind. Last November I bought 3 Baptisia on sale, a plant that establishes deep roots and doesn't like them disturbed (so I've heard). They were terribly root-bound, though so I had to do something. I decided to re-pot them in larger pots, and really man-handled those roots. Unwound them, cut some, spread them out. Then they overwintered in my pot ghetto, surrounded by leaves and protection. You should have seen them grow and bloom this Spring, even before they were planted out!

I suggest you plant in late afternoon so that the first several hours in the plant's new home are not too sunny. As far as rootbound potted plants goes, I tend to be very harsh on those roots. I cut off the "disk" of roots on the bottom, slash the sides a little bit vertically and even pull the root ball apart a tiny bit. It seems extreme but I consider it tough love. I have gotten away with it so far. Sometimes I do my harsh treatment of the roots and put the plant back in the pot for a day or two and then plant it. Liberal watering and mulching at planting time are definitely a good idea. If your planting site is really dry you might even water the planting hole once before you put the plant in the ground and then water again after planting.

I agree with those of you who recommend cutting those rootbound roots, making sure that none of them remain in a circular formation and freeing up roots so that they spread out in over the most soil possible. I do not think that plants can grow well at all if the root system remains in the way it was constrained by the pot. they have to spread out in the ground.

If I were doing this in July I would tackle the root issue,repot it in a larger pot with fresh soil. I would then take it to the spot that you intend for the tree and plant pot and all into the ground so that the soil around the pot comes up to the rim. I would water it regularly and I would mulch it. The Tree will not be stressed from having its root mass reduced and it will have a chance to replace the root system before it has to spread out into the ground

In the spring I would get rid of the pot and replace it into the ground. I do not know if anybody else does this.

Whatever you do, I would not leave the roots potbound

You may want to prune it back some to decrease the water loss. While its a bit late you may even just prune off the oldest/largest branchings which will prepare it for new branching next year.

Personally, I think that cutting the root mass is damaging to the plant and increases the likelihood of transplanting shock. The plate of roots on the bottom pretty much needs to be cut off, but if you can tease out the roots on the sides with a slim pointed rod you may avoid damage and the subsequent healing time.