It would be nice if plant availability and the optimum planting season coincided, or if planting time on a project were planned for cooler weather. They’re not.
Since we’re not in an ideal world, things sometimes must go in the ground during hot weather. The trick, then, is to develop techniques that ensure a high survival rate.
The most critical thing, of course, is water. The plants will need it, even if they’re natives. Once they’re established, watering will become more optional. Right now, after planting, it’s critical.
Once watering issues are covered, what can be done? Shading the plants, cutting back their leaves or heading back stems are possible options.
There may be no difference between trimming the plugs and leaving them leafy. Since all the plugs are in the same area, in the same soil and under the same watering system, the only variable should be trimmed vs. untrimmed. In a few weeks, we should have the answer.