I just bought 2 Wine and Roses Wiegelas and 3 Bloomerang Lilacs for 75% off at a local Ace Hardware Store. Three gallon pots for $7.50 each and $6.25 each, respectively. Should I go ahead and plant them now even though we are approaching triple digit temps or keep them in their pots till fall? I also need to confess that I will have to move a buddleja to free up the location where I want to plant the lilac, and I'm not exactly sure where I want to plant the wiegelas. so I may need to move some other things to make room for them. If your advice to me is to wait to plant them, can I keep them in their original nursery pots?
Yes, plant them now. Never plant a plant in the nursery container. Ensure the hole is twice as big as the nursery container and ensure the back-fill soil is atleast 1/2 compost. Build a moat around the plant once planted at the edge of the roots from the container atleast 2-3" high. Fill the moat to the top with water and let it drain slowly, refill several times. http://ruff.auc.com/how-to-plant-your-tree/ Ensure the plant has enough space based on mature size on the label. Sounds like your impulse buy will be very labour-intensive.
I am with growin' on this, also. As much as your plants might work a bit harder to establish, they'll have an easier time there than you trying to keep them watered in their pots. Not to mention how hot the black plastic pots might get - I have cooked plants by keeping them in their pots during sunny hot spells.
Alas, now you have to work in the heat. Be careful to stay hydrated yourself!
I don't know Boomerang Lilac but Wine and Roses Wiegela is beautiful.