It does sound like your garden has gotten depleted of organic matter. I have very coarse sandy soil, and can't produce anything on fertilizer alone. Once I amend it with lots of organic matter, I don't need to use fertilizers of any kind and get very productive healthy plants. Because organics break down very fast in my soil, I have to amend my soil yearly to keep it productive. I mostly add two-three inches of chipped mulch each year, which breaks down by the next spring and is usually adequate. What you are describing sounds like the same problem the commercial food industry has been running into. Depleted soil becoming less productive and requiring more fertilizer. I suggest what others mention above. Add lots of compost and/or manure, and grow less, but healthier plants.

Who told you the 3-days-at-72-degrees bit? There's a lot of bad tomato folklore out there.... AFAIK, the pollen becomes non-viable if daytime lows are 90-95 degrees and nighttime lows are either below 55 or above 75. There is some variation by variety (and cherries will set at higher temperatures). The FAQ says "Fruit set will resume when temperatures moderate." Why are the blooms on my tomato plant dying and falling off? The only high-temperature effect I'm aware of is on the pollen. So the plant should continue to make flowers, and those flowers should set fruit when temperatures are more favorable. [Have you ever experienced a hot summer where tomato plants continued to grow but no longer flowered?] Now, high humidity is another factor: it also makes pollen non-viable. I don't know the figures for overly-high humidity. And on a stressed plant, tiny, developing blossoms will often drop for whatever reason (I assume mostly either inadequate water or the plant has already set as many fruit as it can take care of).

Sorry didn't mean to imply I was only discussing tomatoes. The issues I discussed above can apply any blooming/fruiting plant, not just tomatoes and not just tomatillos. I too grow both and while there are some cultural differences it isn't a drastic amount and many aspects of the 2 plants are the same - including the causes of blossom drop. Personally my tomatillo plants don't get scraggly or sad looking and they sure don't look like weeds and all my experiments with the various blossom drop sprays have supported what i said above. But then my climate and the effect it has on them is quite different from that in zone 10 (have no idea where the OP is located). They look different from tomato plants in ways but look and act just like them in others. As to the self-pollination issue, it is hotly and often debated and research from Purdue University has the best info on it. https://hort.purdue.edu/newcrop/morton/mexican_husk_tomato.html Studies show that some varieties are readily self-pollinating while others are not. Some varieties require a wider range of cooler temps to self-pollinate, and some plants it seems will never produce fruit regardless of the growing conditions. So there are no absolutes about them. However 3 plants in one container (without knowing if it is an exceptionally large (ie.25 gallon) container is normally over-crowding. And as floral pointed out 1 large bushy plant with another small plant is often indicative of excess or uneven distribution of N in the container. That 2 holds true for any blooming/fruiting plant. Dave

Since it seems you live in my vicinity, check for thrips in your blossoms. Right now my tomatoes are getting hammered by them - they get up in there and suck all the juices out, leaving you with dried up brown blossoms that usually drop off at the joint. If you tap a blossom with thrips in it (or vibrate it with an electric toothbrush), you can literally watch them fall/fly out. For whatever reason they mostly leave my cherry tomatoes alone, and my San Marzanos are still fruiting well, but everything else is struggling. I've been working on Spinosad treatments, which are helping, but it's a thrip plague around here. As another possibility, and easy to check for.