@frillylily I have the same weather (though yours may be harsher, depending on the year), and just try to get my dahlias to limp along until September. If there is no rain, I water relentlessly. Some varieties don't care and bloom perfectly in the heat/humidity...it is a learning curve to figure out what varieties tolerate the midwest weather, but if you ask me, it is absolutely worth it! If you have clay and want them to grow, I suggest adding a bunch of compost to even it out.
