So, I am trying to avert panic; if it's like this now (83!), will we be frying in June, Oh my god, the watering bill this summer, that whole thing.  But, as in most of life, 1) there's no way out but through; and 2) be where you are.
So what am I thinking about doing in the garden right now?  Already I am weeding, and I marvel at the size of the weeds.  But I also see nepeta springing out of the ground like...weeds.  I plant only the (supposedly) sterile forms, but still they seem to sleep around and reproduce.  As well, the ones actually planted get WAY bigger than the literature says.  So, I am already hacking back and dividing.  If you divide now, or soon, the plants will recover so easily you will never know you did it.  Wait until later, and they seem resentful all season long, and turn in for the winter long before they should.  So go get yer spade on.
OTHER THINGS: I am rereading, as I do every early spring, Roy Diblik's "Small Perennial Gardens: The Know Maintenance Approach."  His plant recommendations make for gardens that are filled with both beauty and common sense.  And he's right here near Chicago's North Shore, in Burlington, WI.