Wait until October at the earliest. A potted tree might make it if you put it in the ground in August, but it will be very stressed by the heat, and may lose all of its leaves. A bare root tree would be in even more danger. Why the rush?

Not all tree species do well with bareroot planting and/or fall planting, so check recommendations from you county extension service or state ag department for your area.

Potted trees can be planted at any time, but August is, as Ruffles78 wrote, very risky even with irrigation. Choose the proper species and wait until after natural leaf fall before planting, even for bareroot stock if such is available this time of year.

it is best to plant a deciduous tree .. without leaves ... hence the timing issue...

lets suppose.. for one week.. in august.. due to transplant.. the roots shut off.. and can not support all those fine green leaves...

what do you imagine will happen... well.. those leaves will burn off...

if all else perfect.. a tree could releaf ... but your transplant is already stressed .. so why double stress it.. severely ...

and second.. we would NOT want it wasting all its stored energy.. releafing in fall ... that will lead to die back over winter...

make any sense????

besides... its mid august.. you only have to wait a month or so ... i have 20 pots in the shade.. waiting for planting time...

mid fall is also better.. in that nights are cool.. so no matter how hot the day.. there is a relief period at night.. and we can try to push the envelope ....

but z6 does not tell us where you are... and we cant be more precise ....

make any sense????

ken

ps: planting pots in august.. leaves you at the whim of the seller.. and how well he treated those pots.. let me suggest.. that if its bigboxstore.. the stock they have had since spring.. may or may not.. be prime .... as compared to a high end nursery ... if you insist in august planting.. get a FULL WARRANTY ....

Potted trees can be planted round year as long as ground is not frozen. It's much cooler in the ground than it is left outside in the 100*F weather.

The key is PROPER WATERING. A lot don't do that so they die in the middle of the summer as I've seen that over and over.

Also the size of the tree matters too. The larger they are, the longer period of time you have to care for it.

Here is a link that might be useful: Proper watering

I planted 2 potted trees 3 days ago... the ground here is hard as a rock (very little rain in the last 6 weeks)... I just water and mulch...water water water... sand soil here.

I've planted quite a few potted trees in July/August. I haven't lost any yet and none are losing or have lost their leaves. The advice given does make sense but I think it will also depend on your weather, your soil conditions, what time of day you plant (don't do it in hot blazing sun) and most importantly how well you take care of them after.
The only problems I have run into while planting potted stock in the summer is when plants are in full flower. I've found it's better to cut off the flowers before planting so that the tree/shrub can focus on growing roots instead of flowers.