I'm sure you could still plant okra! If the soil is mulched well to conserve moisture.

How about planting corn? They just love the heat.

The only thing you should put in the ground right now is stuff like okra, black eye peas, sunflowers, sweet potatoes, yardlong beans, Armenian cucumbers (actually a melon), melons, corn, and summer/winter squash (though you're probably going to want to wait a little while for winter squash to protect fruits from burn).

That said...except for the okra, yard long beans, black eye peas, sunflowers, sweet potatoes, and Armenian cukes...most of that stuff will greatly benefit from waiting until mid/late-July for planting (along with peppers, tomatoes, and eggplant at this time) for fall harvest. Aside from heavy water use keeping them alive during the hell of summer, some of this stuff needs to make mature fruits without the hell of summer scalding them to a crisp and ruining what you've spent months waiting for.

If you're planting transplants of any of this stuff rather than direct seeding try to plant on an overcast/shady day or very late afternoon to prevent the sun from roasting your plants.

Basically, if you can wait 3-ish weeks you can plant almost any "summer" crop you want to put in the ground...though you might need to baby them a bit through the seedling stage to keep them from burning up.

I gotta edit and add...

I love Arizona...I visit there so much...it's heaven. I truly don't mind their summers, though I've never had to live there June-August (only visited during that period). The "dry heat" of a 110 degree day I'll take 10 times out of 10 over a 90 degree day with 40+% humidity that's so common in my part of NC. I wish I could find work in my field (agriculture research) in Tucson/Phoenix that wasn't cotton related. There is other agriculture research out there, but it's in out-of-metro areas like Yuma and Eloy...which is just a bit too rural and out-of-the-way for my tastes.

This post was edited by nc-crn on Wed, Jun 26, 13 at 5:13

Found a Maricopa County planting guide for you...in PDF form.

http://ag.arizona.edu/pubs/garden/az1005.pdf

There's also an Arizona Gardenering forum here on Gardenweb that's frequently visited by users...

http://forums.gardenweb.com/forums/azgard/

Here is a link that might be useful: Maricopa County planting guide PDF

I do have armenian cukes, yardlongs, cantaloupe, honeydew, and watermelons going as well as my tomatoes, berries, grapes, peppers, everything is still holding in there but I wanted to plant my three sisters corn, beans, pumpkins, this week I was just meaning holding off a week or so until these 115 degree days are over I don't want to plant seeds and have the seedlings fry or fry myself...
@nc-crn thanks for the planting guide I pulled that up a few months back that is why I was planning on pumpkins in ground now, but thought I would throw corn in for a shade break here and there then I saw the three sisters gardening technique with beans in addition to pumpkin and corn and it looks like a perfect little system...
My younger sister lives in Southport NC. so I know exactly what you mean about taking a dry 115 over a humid 90 degree day.. I have lived here all my life and love it I actually like the heat, but I have never planted in late June or July I usually sit those out and plant for our second season in August...
There are a good number of growers in the metro parts like Rousseau Farms in Tolleson, Martori Farms that is based in Scottsdale, Legend that is local and there are a few growers in Maricopa, but as far as agriculture research is concerned I cannot speak to any work because I am not sure exactly what that entails, if it is work with individual growers, universities, government etc..
I work as a Produce Manager for a large company here ( I know big bad chains, and nasty grocery store produce) lol :) But I enjoy it very much and the opportunity to work with some of these growers and visiting their operations is always exciting.

Captain: From what I've read, the three sisters was particular about what varieties of each veggy was used. Not sure if you know this but I believe it's FIELD corn, DRY beans, and WINTER squash.

Good luck.

Kevin

A big problem with 3 sisters is the corn we grow today is nothing like the corn we grew a couple hundred years ago.

There's not many varieties of 8-12+ ft. corn out there...which was a lot more common back during the "supposed" popularity of 3-sisters type gardening. Many modern varieties top out at 5-6 ft....which many vine type beans can more than out-grow.

There's also fertilization issues in play (corn needs a lot of N, beans suffer pod set issues with excessive N).

It's one of those things that generally works better on paper than IRL, but it's not like it's impossible.

I ordered some seed from baker creek it is an Indian field corn variety I cannot remember the name of right now, I am not concerned if the corn works or not, and for that matter the beans I wanted to plant a small pumpkin patch and thought that planting corn interspersed would help with a little shade break midday, but saw the three sisters thing and it seemed like a plan I ordered rattlesnake beans if they work they work if not no big deal, just an experiment. I was going to border the North side and West side with sunflowers it is in the Northwest corner of my backyard and is walled off with a brick wall anyway it gets full sun from 7am until 6-6:30 pm the planting area is 16' by 16' and I wanted the pumpkins to grow out all over the yard.