clever! Did I mention clever?!!!!

I've watched those same youtube videos and I'd love to try that. I have a big concrete slab in my backyard I was thinking about putting a greenhouse on and growing lettuce, tomatoes, etc hydroponic style. The initial costs are not astronomical. I've just got to convince my husband to go for it lol. So far in my backyard I have fruit trees and a chicken coop. I'm slowly taking it over.

Not exactly hydroponic but for what it's worth I did an experiment with growing tomatoes in non-draining pots, so standing water.

I grow many kinds of plants in non-draining pots. I had great success with this in San Jose CA but results have not been as good here in Phoenix. My current suspicion is what you hit on about the temp of the soil/water. For sure black pots in full sun cook. I re-potted a black pot once and the soil/root ball was so hot I couldn't touch it for very long...the still alive plant got my respect.

I've since tried burying pots in the ground and with some shading but have not seen any real improvement. Many plants still slowly go dormant (stop growing but don't die) as the summer progresses. So the problem I've been seeing may not be the root zone being super hot.

It has been a pretty big disappointment growth wise but also water wise. In San Jose these types of beds/pots were nice because they could be watered once every week or two so they were a water saver, less work. Here in Phoenix the non-draining pots used about as much water as when planted directly in the ground (but less than draining pots). When plants were growing well in early summer, when humidity was also very low, transpiration was shocking to me. Soil was drying so fast I thought the pots were leaking but was just transpiration.

Plants don't like it much above 85F (though they like it right around this temp best). They shut down and wait for it to cool down just like us. They have tricks and we have tricks to delay the shutdown.

Based upon my observation in August with all the rains and a surprising amount of growth I am thinking low humidity may also prevent the plants from growing.

We get 9" of rain in Phoenix area annually (optimistic est.) and a 72" evaporation rate annually. Brutal and unsustainable.

Depending on the plant of course. A few plants seem to thrive in the heat. like mesquite.

I thought humidity was a big factor. But our springs early summer has the lowest humidity and the plants seem to do OK. Like sub 10% humidity, less than kiln dried wood. July/Aug humidity increases yet plants do less well.

So I can't tell if humidity really is a factor, or how much. Most plants just seem to be beat down slowly and by Aug many are just hanging on.

I want to start a hydro setup, nothing too big, probably a lettuce raft system, identical to the mhpgardener vids. maybe a 4x4 or 4x6 footer. Temperature as a concern is in the back of my mind when it comes to the nutrient solution. But I am guessing that the lettuce will surely do better than the tomatoes in the cold outdoor temps, just hoping that the nutrient solution would not get too cold.
I also have a few raised beds and a few in ground beds.
This is my first garden in phoenix, at least first fall garden.
I am trying, swiss chard, spinach, two varieties of kale, collards, snap peas, arugala,and a few lettuce varieties.
SteveF try and post some pics and hopefully I will get some up also

I am a rank amateur and have not attempted to grow tomatoes hydroponically, but do grow them in containers on my porch due to rabbits. (In-ground plants get eaten.) This may sound counter intuitive, but I select "cold climate" variety tomatoes because they are suited to a short growing season and the cooler temperatures of fall, winter and spring. I typically start seeds indoors beginning in late December for transplant into containers by March. Most tomato plants do not set new fruit once the temperature starts hitting the 90s in May, so your plants should have most of their flowering behind them by that time. I have had good results with Sweet 100 and Early Girl varieties, but the tomatoes I have grown in containers tend to be smaller than normal. (I am still learning.) I envy your hydroponics setup. Keep us posted.

I just remembered that the University of Arizona here in Tucson grows tomatoes hydroponically and found the following web site which may be helpful. They used to have a tomato-cam, too. You may try searching for it.

Here is a link that might be useful: Growing Hydroponic Tomatoes