The DTMs listed are from transplant and are only guidelines used for comparing varieties. I believe they list what to expect under average growing conditions, day length, sun exposure etc. These growing conditions vary by location and year to year. If you have ideal conditions like you may have had last year, you may beat the listed DTM by a couple weeks or if not ideal conditions you might have to wait a couple weeks longer than the listed DTM.

I agree with LJ. Here on the farm we look at seasonality (early, mid, late). Even seasonality is a comparative guideline that's variable due to environmental factors.

Shell 6A

bummer! so there's a chance i may not be getting some of my tomatoes until middle of september! i'm in zone 6a. Usually our first frost is early october.

I was wondering if there is a way I can speed things up without transplanting earlier.

If you are zone 6a then it doesn't jive with Memorial Day planting or a last frost date of "end of May-1st of June". Those are zone 5a dates.

You might want to double check that info as something doesn't line up. ;-) Most all of zone 6 is a last frost date of April 15th to 20th with plant out date of May 1st. Granted the dates may vary a bit from source to source but yours are off by at least a month.

You can look up planting dates and even micro-zones online by zip code, specific city, and even zones within a city.

But if you are actually in 5a with a frost that late then yeah, you'll do best with early and mid season varieties rather than late season varieties unless you want to use season extension techniques on both ends.

Dave

DTM is like "human lifetime". Depends on a whole lot of things but, in the mean, it seems to be representative of at least some subset of the species.

"If you are zone 6a then it doesn't jive with Memorial Day planting or
a last frost date of "end of May-1st of June". Those are zone 5a
dates.

You might want to double check that info as something doesn't line
up. ;-) Most all of zone 6 is a last frost date of April 15th to 20th
with plant out date of May 1st. Granted the dates may vary a bit from
source to source but yours are off by at least a month."

Hate to disagree, Dave, but the latest hardiness zone maps have me in 6a and there's no way I'd be planting anything that likes warmth before mid-May. Even if a frost doesn't occur the soil will still be too cool for much, if any, growth. The plants would just sit there and sulk. The OP may be off by a couple weeks but certainly not by a month.

Rodney

Well said. Also the seed companies list DTM based on the best growing environment, mostly in the south. Up north, especially in cool PNW I add 20 days to those numbers. Take 4th of July and Early Girl ( DTM OF ~ 55 ) mine took about 75 days.

Also plant size and health can make a big difference. A healthy 8 weeks + plant should give you much early fruits than 5 to 6 weeks ones.

I like to count from sowing seeds to maturity. Most tomatoes will have ripe tomatoes anywhere from 85 to 120 days. Amazingly that is how potatoes do.

sey

Hey Dave,
So I went to research frost date and zone... Got a lot of variable answers. I think some of it has to do with the data being given in percent probabilitiea of frost. Depending on source, I'm in zone 5 or 6.
I think the best source I found for frost date is:
https://www.ncdc.noaa.gov/climatenormals/clim20supp1/states/MI.pdf
If you go by Flint, it puts it at May 19th- or well that there is only a 10% chance of frost after this day! I am new to this area and was still going by when my dad always did his transplants, but he lives farther north so I guess this makes sense.
If your zipcode was 48507, what would you go by?

I'm in 6b/7a, and the oldtimers around here still swear that tomatoes don't go out until Memorial Day. Go figure. Last year, for reasons I didn't intend, I didn't get my plants out until the first week of June. I had tons of tomatoes by August. In addition, a killing frost didn't happen until practically the beginning of November last year, so I had a long and productive season.

The thing is, around here, a late plant-out will work most years. The change in seasons is fast--it very quickly becomes warm, not like places where spring limps along with above-freezing-but-still-cool weather for a long time. It's not great for veggies that like cool weather, but it works great for tomatoes, peppers, etc. And summer is hot but not so brutal that production shuts down entirely. Plus, we reliably get good tomato weather through September and, in recent years, even well into October. So a tomato plant put out late here grows quickly and produces fairly quickly and well. However, in other places that have the same zone but different warming and cooling patterns,, this may not be the case. If frost comes early or if summer heat is a real problem, that may not work.

Glenn and Linda Drowns of Sandhill Preservation are in 5b in Iowa. But they say they start their tomatoes mid-May now and don't plant them out until mid-June. Apparently, they have fewer disease issues with this schedule and still get plenty of tomatoes. It works for them. *shrug*

Long story short: everything about gardening is about the details of local conditions. Zone is important information but far from the complete picture.

In many parts of 6b and 7a we can plant out mid-April but we still have many old timers who subscribe to "Mother's Day". But then we also don't get frosts until late October so even with the MD planting the season is still long enough for even late season tomatoes.

But if your season truly is only Memorial Day to mid-Sept. then you are screwed unless you pre-warm soil (easy to do Rodney) to gain a couple of weeks up front or plan to cover in Sept to stretch things out.

If I had to wait until Memorial Day to even plant I might as well skip the season because within 2-3 weeks it will be too hot for fruit set.

I looked up several Flint, MI plant out calendars and the all say mid-May (last frost 5/5) but they also say first fall frost is 10/8 so if that is accurate then you have 120 days using that format. Might have to do a little ground warming to get the best out of it.

Dave

I'm in 6A ..... 38.5722 Lat vs. Flint 43.0125. We are ~300 miles south of Flint, MI. Our LFD is ~4/20. Recent history indicates that we will have at least one frost "scare" sometime between 4/15-5/1. Every year we plan to plant out the 3rd or 4th weekend in April depending on the WX forecast. In 2016 we didn't get them in until the first weekend in May. In 2015 we got them in the 4th weekend in April. Our old timers subscribe to "after Mother's Day" as well.

Our FFD per academia is in Mid October. We usually have a scare in late October. Last year the FF was 11/13. In 2015 it was 11/21.

We plan on 175 days in our 6A environment. The last few years our fall crops have been extraordinary. For example, we do spring and fall potatoes as well as spring and fall green beans. The last several years, the fall crops have out produced the spring ones.

Shell 6A

While I'll agree with many comments, as a high tunnel grower I know that light is not the limiting factor to harvesting tomatoes closer to expected DTM dates. If you can increase the temperature, both day and night, you will be harvesting in relative same time after transplant as plants set out a month later.

Many Ag crops such as corn use the term "Growing Degree Days" to predict the crop maturity date. Tomatoes follow those same basic growth pattern. When I transplant my tomatoes into a heated high tunnel next week I fully expect to be picking first tomatoes by the end of May.