You would need to buy some bagged topsoil to pot your aquatic plants in. It is cheap at big box stores. Many tropical and hardy aquatic plants thrive in Phoenix, I had a ponding friend there who had a business selling off her extras as they grew so fast. You didn't say you were in Phoenix that is just where I used to live. You can grow plants from tubers at the Asian market. You can also get them from other ponders, a lot cheaper than retail. There is an exchange as part of this forum and there are others too if you google. Many allow plants to be sold but this one does not. Many aquatic plants are fast growing and small starts are fine. There are not so many that are suitable for a home gardener to grow for food production. Most are ornamental.

Osmocote® Azalea, Camellia, Rhododendron Smart Release® Plant Food is a good fertilizer. I like Holytone or MagAmp better, but all three are good. Whatever you do, DON'T follow the directions on the Osmocote package. Do not mix the fertilizer into the top 1 to 3 inches of soil. That is where the roots are since rhododendron and azaleas have shallow roots. Do not cultivate around rhododendrons and azaleas. Just mulch them. When fertilizing, pull the mulch back, sprinkle the fertilizer on top of the soil and then put the mulch back over the fertilizer. Also, do not reapply every 4 months. Only fertilize in the spring and at half the rate on the package. The primary reasons rhododendrons and azaleas decline is: 1) poor drainage. They need well drained soil. 2) soil not acidic. They need an acidic well-drained soil. 3) too much shade. They need an acidic well-drained soil in a location that get at least 2 hours of sun each day in order to set buds. 4) drought during summer. The need to be kept moist (not wet) while they are forming flower buds during the summer. For many of us, this past winter our plants took a beating with the very unusual winters some of us had with warm weather followed by late freezes. They have what is more typical of drought damage but in this case was caused by the warm weather followed by late freezes. It causes Botryosphaeria dothidea which causes leaves to turn dull green and then brown and roll and droop. Cankers form on branches which may girdle the branch. This is the most common disease of rhododendrons in the landscape. A typical symptom of this fungal disease is scattered dying branches on an otherwise healthy plant. Leaves on infected stems turn brown, then droop and roll inward. These leaves often lay flat against the stem and will remain attached. The pathogen can infect all ages of stem tissue through wounds, pruning cuts, and leaf scars. Heat, drought stress, and winter injury can increase disease incidence. Cankers on branches can gradually grow through the wood until the stem becomes girdled. Diseased wood is reddish brown in appearance. Discolored wood viewed in longitudinal cross section often forms a wedge that points toward the center of the stem, and the pith may be darker brown than the surrounding wood. Sanitation and applying a fungicide such as metalaxyl (Subdue) after pruning my provide some control. Plants should be grown in partial shade, with mulch and kept well watered during dry periods. All dying branches should be promptly pruned out in dry weather and all discolored wood should be removed. Plants should also be protected from rough treatment during maintenance activities to prevent unnecessary wounds. Here is a link that might be useful: How to grow rhododendrons and azaleas.

The choices for "shouldn't drop "too many leaves or pods" is a question of whether they want the continual small dribble of leaves, pods and debris from an evergreen, the peaks and valleys of the leaf drop, pollen drop, pod drop, leaf drop of the mesquites ... or the once-a year leaf drop of an elm or ash. Australian Willow (Giegera somethingorother) is a nice evergreen, very tidy, pretty bark. Mexican ebony has lovely smooth patterned bark. The sterile Desert Willows have the annual leaf drop, flower and drop blooms, but don't set seeds. Colorful foliage ... the above-mentioned pistachio Look for trees classed as "patio trees" in Sunset's Western Garden book.

The overhead shade will help, but with the temperatures that were having right now, it's tough, especially for container plants. As far as light, there is probably plenty for them to survive. You will need to watch the water though, it can be tricky. You will see your plants wilt down in the afternoon and want to water them. Be careful. Plants will wilt because they can't take up enough water to keep up with transpiration from the leaves.If they haven't bounced back by late evening or morning they may need more water.If you over-water at these temperatures and the soil stays too moist you're inviting fungi and root rot. The lavender, rosemary and sage should do okay with less watering. Likewise the peppers. Tomatoes and cukes are a little more difficult. A moisture meter helps take the guess work out and they're not expensive. There are a few that have a light meter built-in. The plants that are lacking light will start to grow toward the light and start looking "leggy" rather that full. Rotate your pots every week or two to help keep the growth balanced. One way to help keep the soil temps down is to water with ice cubes anduse mulch in your pots to slow evaporation from the soil.Hope this is of some help.