I think from what I've read and what we've experienced is that keeping the plants really well-watered and growing fast is the key to rebloom. Our garden gets very dry (rain stops/sandy soil) about the time the first bloom is completed. If we don't water, the plants really slow down and we don't have much rebloom.

We're going to keep them very well watered this season, and if I find time I'll throw on some fertilizer, too. Of course, you have to have plants with reblooming genes for this to make a difference. Bob

Me? I just enjoy them...I usualy get a lot of rebloom, but the plants have been on their own this year, so we'll see what happens.
kay