This is the guide I use for planting seeds and transplants in Phoenix. I think most people start tomato and peppers from seed indoors (or greenhouse) in December - January-ish.

Maricopa County Garden Planting Guide

There's not a whole lot you can do in June/July/August due to the excessive heat, but check the Guide, there's a couple things you can do.

You'll get a lot of different info on gardening because the techniques for gardening change depending on where you are, and what you're trying to grow. One reason I like container gardening is you remove a few of those variables, and the information on it is more consistent.

You might not want to use a greenhouse in the summer, their main purpose is to keep frost away from plants in the winter. Just get a few containers, and try growing something on your patio in those. Peppers are a good plant to begin with as they work well in containers. If you're going to grow them in the summer, most varieties will do a lot better in shade for most of the noon portion of the day. It's still easy to get them at least 6 hours of sun each day doing that.

As far as transplanting, it's generally best to do it in ideal weather for the plant because there's usually some stress on the plant when you transplant them.

I've never used the aqua globe, but I love by the automatic watering system I use (1/2" and 1/4" distribution tubing with a timer)

If you get a chance to grow something in the ground, you can start armenian cucumbers in the summer here, they love the heat.

The Maricopa County Guide from azbolt is a good one, here's one more. Has a few different items. Low Desert Planting and Harvesting Guide - The Urban Farm Looks like: basil, beans, corn, okra and squash are ok to start in summer. Good luck and happy gardening.

You can start planting winter veggies in late summer: bok choi, chard, spinach, etc. they'll grow all winter for your fresh greens.

Heat lovers like okra and Armenian Cucumbers can be started in the grouns as soon as it warms up. they LIKE heat.

One of the better planting times for native trees and shrubs is right after the humidity soars in late June. We hate it, plants thrive.

Heat lovers like bougainvillea - plant in late spring

Not so fond of heat, like roses - plant in early fall