Since no one's answered this, I'll take a stab at it using my failure as a guide. The only time I've had even partial success with these was one year when we had a freakishly long, cool spring. Even the "heat proof" ones I've planted just can't take the heat.

As you know, Midwestern summers are known for suddenly blowing in hot and heavy, and your beautiful city gets about as hot as it does here. So even though I think you're supposed to space out plantings in places where they flourish, I vote for planting early and all at once in order to enjoy them while you can, because in my experience they die as soon as summer hits.

And P.S.--if I'm wrong and there's something else I could be doing to grow these, I hope someone will let me know. That goes for you, too, tropicanarama--if yours do well, please let us know, and good luck!!