Not really.

I too have noticed that the flavor of some of my varieties goes off with the cooler fall weather :(. Here's a suggestion. This year, enjoy them early in the season, then pick the rest and dehydrate or freeze them :) Maybe grow another variety to enjoy in the fall.....

Linda

Is this something you get from old, second-season tomatoes, or is this something that happens generally for newly planted fall tomatoes? That is, is it about old plants, or is it about fruiting in cooler temperatures? I've never done either, but have considered doing so.

Lucky you, living in TX and getting two seasons of tomatoes :). For us in the frozen north, we only get one season, and it's true that some varieties taste great early, then the taste changes and is not so good when the weather cools off. Other varieties do the opposite......

Linda

Tomatoes don't ripen well in the cold, so fall tomato gardening here has some disadvantages. Also, (let's call it) spring here is longer than (let's call it) fall. If I plant out in mid-Feb, immediately after last frost, fruiting stops in June, and I've got everything picked in July (5 months), and pulling those plants and starting new plants in August, I need to finish production before first frost in December (4 months).

But seriously. Cool weather makes for less sweet tomatoes?

I lived in Z5 in northern NY for 15 years, and yes, the quality of the tomatoes goes down hill big time as the season gets late. My wife used the late red ones for sauce, and I've heard you can pickle the green ones, but never tried it.

Very interesting. Thank you. I guess it makes some sense in that plant sugars are developed by photosynthesis. So it may be more the decreasing sunlight in the fall than the cool temperatures that result in less sweet tomatoes.

Another use for green tomatoes is green tomato relish. Or fried, my favorite.

Have noticed that the fall green tomatoes are also more tart and better tasting for fried green tomatoes.

Last year September was hot; maybe the shorter days caused the sour taste?

I guess the question, that someone ought to be able to answer, is whether summer-planted, fall-harvest tomatoes taste better than spring-planted, fall-harvest tomatoes. If so, then it's age that determines the taste of fall-harvest tomatoes. But if all fall-harvest tomatoes taste poor, then it's about cooler temperature or lack of sunlight. Gracie's observation suggests that maybe it's the latter.

Dan, you must have overlapped Dave’s comment which answers your question. I’ll add that nutrients like Potassium also have a tendency to be deficient as the season progresses. Potassium has a definite impact on tomato fruit texture and flavor.

I think that's right about potassium deficiency late in the season. Plants don't just take up the potassium that they need, but potassium that is there. That is, they suck up more than they need, and render the soil potassium deficient. Of course, if tomatoes suck up more than they need, maybe it's unlikely that they will miss it if less is left in the soil?

Dan, if they do take up more Potassium than they need that K would show up in a leaf analysis and one PSU Extension tomato researcher, Steve Bogash, reported abnormally low tissue Potassium levels which he was not able to bring up late in the season by fertigation or foliar spray. Tomatoes (the fruits) pack a lot of K so high production requires a lot of it.

What do I need to do (buy?) to add potassium?

While tomatoes may be deficient in potassium late in the season, I don't think that's a clear answer to the question of why late season tomatoes don't taste as good. There are a lot of things different late in the season. You could buy some more heat and light, or new tomato plants as well.

there can be a number of factors that can influence flavor besides the plant just being 'old' i think, and i'm certainly skeptical of it unless it's a year old tomato plant or some over-wintered plant.

greenhouse tomatoes generally aren't as good tasting as field pick tomatoes. my brandywine tomatoes taste better than the same tomatoes grown in a greenhouse just around the block. i've read a few books and many mention that greenhouse plants do not receive proper UV light compared to the outdoor plants. hence in the fall, there is less UV/light, which in turn can alter flavor of fruit

but there are can be other causes too. soil fertility? could the soil be lacking nutrients in the fall? do you fertilize after a first harvest?

what about plant health.. is the plant still lush and green? any signs of diseases starting to rear its head?

then there is the weather.. more rain/water in the fall? it's known that too much water/rain can dilute the flavor in tomatoes. pay attention to the weather when you notice a change in flavor..

have a read at this article, in regards to some of the things i mentioned. more sun = sweeter fruit.

That's a good article, Stevie. Thanks. See this too.

https://www.acsh.org/news/2016/09/19/uv-light-adds-flavor-out-season-greenhouse-tomatoes-10185

It is true that fall tomatoes are going to be woefully deficient in UV light. As sunlight decreases, mainly because the sun gets lower in the sky, the amount of UV from it drops precipitously. That's because the atmosphere is pretty opaque to UV light, and a low-down sun is shining through more atmosphere than a high-up sun. That's another reason why (without snow to reflect light) you almost never get sunburned in the winter.