|When is the last day to plant a tree, most likely a pink flowering dogwood in the spring. I live in zone 5.
|There is really no specific day, it will depend some what on the weather.
Generally speaking, if your tree is container grown and has been kept outdoors at the nursery, you can plant it almost any time the ground is not frozen or too muddy to dig. If it is bare root and dormant, it should be planted in late winter to early spring so it can wake up naturally with the season.
It is best to plant very early in the spring or in the early fall at least 8 to 10 weeks before the first expected frost. Midsummer is not the preferred time to plant because it is so hot then and that is stressful on the plants while they are trying to become rooted and established.
In spring, the earlier you can plant, the bettter. The only reason to wait would be if the tree is leafed out or leafing out and has been sheltered in a green house and is very tender -- and there is frost or freezing weather in the forcast. In that case you might wait until the danger of frost is past.
It is difficult to hold a plant for any length of time under home conditions. If you already have the tree, plant it as soon as possible, do not wait.