DTM

[karstopography]

What is this, pick a number out of a bin like bingo? Is there any standardized or governing body that audits the days to maturity listed by various seed vendors and/or fact checks the listed numbers for authenticity?

For example, I’m currently growing Gregori’s Altai
Tomatofest lists the DTM at 90 days
Reimer’s at 78 days
Tomato Growers Supply at 67 days

Really, I’m kidding about the fact checking, but 67-90 days is a pretty wide range for one tomato cultivar. Does anyone have a favorite source that generally has the best numbers on days to maturity? Or are some cultivars more prone to being wildly variable on DTM? It might be kind of nice to have an idea ahead of time on what is to be expected from a particular tomato, wouldn’t you think?

[worth1]

I have seen no reliable sources on the subject.
It all depends on when you start the clock.

[Shule]

I usually pick the vendor whose climate is most similar to mine (if they grow their own seeds). I read a lot of reviews, too, with regard to how early they mature.

[Shule]

For me, Gregori's Altai was kind of late, but it was still hot (not cool) when they began to ripen, I think (Sasha's Altai was much earlier).

Let's see where those vendors are from:

TomatoFest: Little River, California
Reimerseeds: Saint Leonard, Maryland
Tomato Growers: Fort Myers, Florida

I'm not sure where they get their seed, though. I'm guessing your climate is more like that of Tomato Growers. Gregori's Altai probably likes phosphorus, warmer soil, or more acidic soil, I'm guessing. (I didn't grow it with black plastic. I had it in drought conditions, probably in somewhat alkaline soil.)

[karstopography]

I usually pick the vendor whose climate is most similar to mine (if they grow their own seeds). I read a lot of reviews, too, with regard to how early they mature.

This is a very good point. Where the seed vendors are located might be determining the DTM.

[karstopography]

For me, Gregori's Altai was kind of late, but it was still hot (not cool) when they began to ripen, I think (Sasha's Altai was much earlier).

Let's see where those vendors are from:

TomatoFest: Little River, California
Reimerseeds: Saint Leonard, Maryland
Tomato Growers: Fort Myers, Florida

I'm not sure where they get their seed, though. I'm guessing your climate is more like that of Tomato Growers. Gregori's Altai probably likes phosphorus, warmer soil, or more acidic soil, I'm guessing. (I didn't grow it with black plastic. I had it in drought conditions, probably in somewhat alkaline soil.)

So far, Gregori’s Altai here has been one of the first to set fruit and had the biggest so far and nearly the most fruit on it. I don’t know exactly when I’ll be getting ripening fruit, but I’m more on track for the lower end on the range than the upper. 70 days or so seems like a reasonable guess at this point.

[karstopography]

@Shule you really might be onto something about the location of the grower. I looked up Little River, CA where tomatofest is located. Right on the Pacific just below Mendocino in Northern CA. Climate data for that area I would describe as very cool, never hot.

I wonder if it is a good idea to get seeds from vendors in like or similar climates or does it not matter in the slightest?

[bower]

That is an extreme range, for sure. Usually the ballpark of "early (60-70)" "midseason" (70-80) or "late" (85+) is a reasonable guide.

But earliness is one of those complex traits that isn't easily fixed. AKMark pointed this out to me, that he had to select for earliness in every generation. And there is always a bit of a range at least a few days, even amongst seedlings of the same stable cultivar. There can also be environmental triggers that cause certain vars to delay fruiting or ripening, outside of their 'norm'. Those traits wouldn't even be noticed, if they were selected in an environment that didn't expose them to those triggers.
The best thing to do is to make your own notes and save seed from your best performers. It may vary some from year to year, but after some time you may find it stabilizes around a value that fits your environmental norms. It could well be that these different seed sellers selected different strains of 'earliness'. So it might be best to get the earliest strain, if that is important to you.
It would be interesting to grow out seeds from all three side by side, to see if there is a real difference.

Growth habit is another complex trait that sometimes produces 'surprises' even in plants that are otherwise apparently 'stable'. It's not uncommon to hear people comment, that the "compact" plant is long and leggy for them or vice versa. These are the kind of heterozygous genes that float around in that small percentage of instability and only manifest in certain combinations or environmental triggers.

[Sue_CT]

Honestly, I don't know how any of them determine DTM. I just went back and checked my own records. I picked my first tomato (most years at first blush or light red) anywhere from July 8th (2020 Box Car Willie), to August 15 (2020 Stupice, ML and KB on the same day). I didn't record which year it was but one year my first tomato was Brandywine! Usually a late tomato for me. In 2020 for instance, it was a very late year, but Stupice which is supposed to be one of the earliest tomatoes, was picked on the same day as ML and KB, both usually mid to late varieties. There is so much variability based on weather, at least in my area, that I don't know how they make anything except generalizations. Maybe they keep track numerous years in a row and average them out. I still think DTM is helpful but for me only in that it helps me try to plant some generally early varieties as well as some mid and avoid most with really long, late DTMs because I often don't have a season long enough to get much from them. I guess I think the areas where they have the longest seasons and the best weather for growing tomatoes are probably the most accurate as it likely minimizes the effect of the weather on the DTM.

[Vanman]

I don't pay any attention to DTM. They are ripe when they are ripe. Some years earlier than others.

[Sue_CT]

I do pay attention because i want a couple in the 60-70 DTM range and none in the 90-100 DTM range or later.

[Tormahto]

What is this, pick a number out of a bin like bingo? Is there any standardized or governing body that audits the days to maturity listed by various seed vendors and/or fact checks the listed numbers for authenticity?

For example, I’m currently growing Gregori’s Altai
Tomatofest lists the DTM at 90 days
Reimer’s at 78 days
Tomato Growers Supply at 67 days

Really, I’m kidding about the fact checking, but 67-90 days is a pretty wide range for one tomato cultivar. Does anyone have a favorite source that generally has the best numbers on days to maturity? Or are some cultivars more prone to being wildly variable on DTM? It might be kind of nice to have an idea ahead of time on what is to be expected from a particular tomato, wouldn’t you think?

Generally, when I see three widely differing numbers like that, I throw out the high and low, and use the middle as a rough guideline. However, my grow out of Gregori's Altai was about 67 DTM.

There are just too many variables, like how old is the plant on the transplant day, what's the weather like (degree days, etc...), and to me a very important one - did the first flower on the first truss set a fruit. If the first flower doesn't produce the first ripe fruit, but another flower from the same truss does, there will usually be a delay of about 3 to 4 days. If the first ripe fruit is from the 2nd truss, that's usually a 7 to 10 day delay in having a ripe fruit. Further delay of a day or two, may be due to the size of the tomato harvested on that plant, a giant taking longer than a runt.

[Tormahto]

For me, Gregori's Altai was kind of late, but it was still hot (not cool) when they began to ripen, I think (Sasha's Altai was much earlier).

Let's see where those vendors are from:

TomatoFest: Little River, California
Reimerseeds: Saint Leonard, Maryland
Tomato Growers: Fort Myers, Florida

I'm not sure where they get their seed, though. I'm guessing your climate is more like that of Tomato Growers. Gregori's Altai probably likes phosphorus, warmer soil, or more acidic soil, I'm guessing. (I didn't grow it with black plastic. I had it in drought conditions, probably in somewhat alkaline soil.)

So far, Gregori’s Altai here has been one of the first to set fruit and had the biggest so far and nearly the most fruit on it. I don’t know exactly when I’ll be getting ripening fruit, but I’m more on track for the lower end on the range than the upper. 70 days or so seems like a reasonable guess at this point.

A bit of caution on GA. In my garden, it's one of the worst splitters, stem to blossom end and back to stem, with heavy rains.

[Shule]

While I don't think there's a central governing authority on days to maturity, you might contact university plant breeding departments to see how they do it. Johnny's Selected Seeds might be another place to ask (they're a big enough company where they make enough money that they have to charge sales tax to every state; so, if there's a united process that the tomato seed industry uses to any degree, they would probably know).

@Shule you really might be onto something about the location of the grower. I looked up Little River, CA where tomatofest is located. Right on the Pacific just below Mendocino in Northern CA. Climate data for that area I would describe as very cool, never hot.

I wonder if it is a good idea to get seeds from vendors in like or similar climates or does it not matter in the slightest?

I don't think days to maturity is one of the traits that is normally impacted terribly by the location of the vendor (it seems more impacted by the location and soil, etc. of the grower). You'll get lots of reviewers of the same product stating wildly different DTMs, at times. It's more the vigor, production and hardiness that vendor location seems to impact (as far as I've noticed in my experimentation there, anyway).

I get excited about vendors in similar climates, but I wouldn't write anything in scientific stone about it. I know a lot of southerners like Tomato Growers, though. I liked it reasonably well, too. It's possibly just a good company. (But I like seeds from Florida growers who aren't vendors, too; I generally like seeds from areas with heat-stress, with some exceptions; Florida isn't an exception).

My favorite vendor is actually in Nebraska (timelesstomatoes.store). I'm not too sure what Nebraska is like (I've never been there), but I imagine it's colder than my area (and probably similar in many other ways, with regard to things like elevation, hardiness zone, northern similarities, and stuff; I imagine it's not humid there, but probably not as dry as my area). I'm comparing their Amana Orange with mine, this year; so far, theirs is winning out, germination-wise, which was kind of surprising (a few of mine sprouted first, but overall, theirs is sprouting better, earlier on).

[Tormahto]

While I don't think there's a central governing authority on days to maturity, you might contact university plant breeding departments to see how they do it. Johnny's Selected Seeds might be another place to ask (they're a big enough company where they make enough money that they have to charge sales tax to every state; so, if there's a united process that the tomato seed industry uses to any degree, they would probably know).

@Shule you really might be onto something about the location of the grower. I looked up Little River, CA where tomatofest is located. Right on the Pacific just below Mendocino in Northern CA. Climate data for that area I would describe as very cool, never hot.

I wonder if it is a good idea to get seeds from vendors in like or similar climates or does it not matter in the slightest?

I don't think days to maturity is one of the traits that is normally impacted terribly by the location of the vendor (it seems more impacted by the location and soil, etc. of the grower). You'll get lots of reviewers of the same product stating wildly different DTMs, at times. It's more the vigor, production and hardiness that vendor location seems to impact (as far as I've noticed in my experimentation there, anyway).

I get excited about vendors in similar climates, but I wouldn't write anything in scientific stone about it. I know a lot of southerners like Tomato Growers, though. I liked it reasonably well, too. It's possibly just a good company. (But I like seeds from Florida growers who aren't vendors, too; I generally like seeds from areas with heat-stress, with some exceptions; Florida isn't an exception).

My favorite vendor is actually in Nebraska (timelesstomatoes.store). I'm not too sure what Nebraska is like (I've never been there), but I imagine it's colder than my area (and probably similar in many other ways, with regard to things like elevation, hardiness zone, northern similarities, and stuff; I imagine it's not humid there, but probably not as dry as my area). I'm comparing their Amana Orange with mine, this year; so far, theirs is winning out, germination-wise, which was kind of surprising (a few of mine sprouted first, but overall, theirs is sprouting better, earlier on).

Here at T'junction, greenthumbomaha could likely tell you what the weather is like in their part of the state.

[MissTee]

I usually pick the vendor whose climate is most similar to mine (if they grow their own seeds). I read a lot of reviews, too, with regard to how early they mature.

This is a very good point. Where the seed vendors are located might be determining the DTM.

You would think that. But haven't found it to be the case. A local grower just down the road from me (okay 45 minutes drive away) has often fudged their DTM. Saying 70-ish days when in actuality it is close to 90 days is just wrong. Almost 2 weeks later puts a mid-season prediction into late season territory. And based on where I live, I know late season will not do.

Don't get me going on 'mid' and 'late' monikers. That add too much vagueness.

There is no truth in advertising.