Hmmm. Sounds like you made a major investment in your landscape. I'm not an expert, however, I do have a mix of drought-tolerant plants, natives, and traditional plants, but I only hand water once a week, and the natives only once every 2 weeks. Usually, I try not to water unless it's a new plant, or I see something wilting. Plants, in general, seem to be a lot more drought tolerant than we think. But it might also be the frequent shallow waterings. I might try longer, deeper soaks less often. It could be your soil. I recently went to Las Pilitas and they have some very strict recommendations about planting natives. They tell you to do a deep soak when you first plant them (which is very important) and then once a week or so (depending on the plant) for the first few months (sometimes up to a year) and then back off. I recently planted 3 drought-tolerant plants in the same general area, did my deep soak...and a three weeks later, 2 are going gangbusters, and one is shriveled up and brown. The only thing I can figure is there's something in the soil that killed it.

Are you checking your ppms in the reservoir or just topping off with nutrient solution? Tomatoes are heavy feeders but you should be seeing nutrient deficiencies well before the plants are dying. How do the roots look in color? Also are the tomato roots much longer than the other plants? What can happen is the tomatoes can suck up so much water and have more access to the nutrients in tank that either 1. The water level drops too low for the other plants roots to have access or 2. As you said they could be using up the nutrients but you would be seeing symptoms of that Edit- I just read about the spider drip system which means checking your res ppm might not be that important after all. How often are you checking the water level?

@John (Zone 5b/6a, IN) Your comment of the " water with nearly reckless abandon" had me in fits, especially after your "proper moron" statement regarding ferrying the plants to and fro. (Disclaimer: I did all of that, and more, perhaps i win in the moron dept) Just thought i'd pop in to comment, that my journey on the 'perfect' gritty mix also went through many evolutions such as yourself. I think i've matured a little as a gardener. It is as you say. In the beginning, I went out of my way to follow Al's mix religiously, even to an obsessive point to import Lbs of the product from overseas to be shipped to Singapore (where i reside). At that time I never considered the purpose of the gritty mix - instead i wanted to build someone else's mix. In case anyone from Singapore or any tropical climate comes to read this comment, over the years i've found my own version of the perfect gritty mix, which in the usual 12" tall pots of various width i use for my plants has come to be my go-to mix for everything, such as eggplants, habaneros, thai chilis, winged bean, and even my flowering plants like zinnias, cosmos, marigolds, etc. A little preface for my own mix is due to the region I (and my plants) live in. Generally speaking, my climate is 6 months of horrendous "dry" heat (60% relative humidity) and intermittent rainfall (couple of showers every 2 weeks), night temps of 29C (84F), afternoon highs of 34C (94F). Then next 6 months is monsoon season with "wet" heat (85-95% relative humidity) night temps of 27C (81F) and afternoon highs of 32C (90F), with showers every few days and torrential thunderstorms (i.e. localized flooding) every 2-3 weeks. However, being on the equator means our sunlight here is unparalleled throughout the year, and pots are baked for 12hrs a day of sunlight. The gritty mix that worked for me was; 3 parts sifted pumice (6-9mm size) <porosity is great, lots of surface air pockets for roots 2 part bark fines (4-8mm size) 1 part fine LECA (4-8mm size) < i'm lucky that this comes in a prepared bag, no sifting needed 1 part coarse vermiculite (4-8mm size) <need this or i might be watering twice a day... Given that in my heat, there is absolutely no chance of roots being starved of oxygen, since I wanted in the mornings, but even the 2" perched water table in my mix gets drunk up by the plant, on especially hot days the eggplants even need a little drink in the afternoon. The sometimes oppressive heat means the plants respire/transpire lots daily to stay alive. I water using the garden hose, i fill the pots up to the top with water. i have these mini fertilizer baskets which has a slow dissolving general 8-4-3 + TE so that takes care of the fertilizer needs. Only once every 2 weeks i go round with the 3 gallon watering can with 0-52-38 (half strength) and pour some on the fruiting plants. For tomatoes, i follow the above, but i add in 2 parts of cocoPEAT, that has worked well for me in my soil structure. I had to cut back my 18ft tomato back down to 6ft because of the excessive water usage such large plant requires. Putting out new flowers as I type this and likely i will another crop of black cherry tomatoes soon. Sorry for the long-winded post - haven't posted here in a while but @John (Zone 5b/6a, IN) @tapla (mid-Michigan, USDA z5b-6a) both made greater contributions in this thread, felt the urge to contribute my small part.

I live in Miami, FL and planted 6 plants about 2 feet apart with same planting/water technique/schedule. 5 are thriving, 1 died, I planted another, and its now dead. I mixed planting soil with the existing soil for all, drainage is good, they are part shade plants in a part shade area. Looking for suggestions before I try to re-plant.