Very early determinante tomatoes

[Nan_PA_6b]

It won't be a good comparison this year, because you can't put them in the cold bed with the others. Since Tormato will send you more seeds, maybe they should wait. Unless you are very eager...

[MrBig46]

Plants from sowing 1.11.2018 are already blooming. I really like the really low plants of Mongolskyi karlik and Sarayev Shtambovyi (in the front row), which are only 3-5 inches tall.
Vladimír

[MrBig46]

In a moment spring will start with us. It's near day D when I'm going to put tomatoes in a hotbed. When growing in a closed hotbed area I always had problems with the blossom drop and reduce tomato fruit. The reason was high relative humidity and low night temperature.
Theoretical basis:
Tomato fruit do not set until nighttime temperatures are above over 55 ° F for at least two consecutive nights (Chester 2004, Ozores-Hampton and McAvoy 2010).
The ideal RH for tomato growth and development is between 40% and 70%. If RH is higher than the optimal range, the pollen will not shed properly (Mills 1988, Ozores-Hampton and McAvoy 2010).
Yesterday, I set up my hotbed. I will be watering a pipe placed in the middle of the bed. I'll plant tomatoes in a woven black foil. The entire bed area will be covered with a thin cover foil to prevent evaporation of water from the soil into the space above it. This is what I tried last week - RH managed to reduce me to the optimal level.
Vladimír
PS.: Two fotos from yesterday

[MrBig46]

The weather forecast is favorable and so I will plantthe seedlings into the cold frame tomorrow. I have somewhat higher seedlings but they all have flowers, just some already blooming. There will be seventeen plants in the cold frame. Sophieś choice (4), Sarayev Gruntovyi (4), Poranok (2), Sasha Altai (1), Stupice (1), 0-33 (1), Bielyi Naliv (1), Alka F1 (1), Krainyi Sever (1) and Independence Day (1)
Vladimír

[MrBig46]

Yesterday, 55 days before May 15 (the day of last frost) I planted my tomatoes in my cold frame. Maybe I'll have the first ripe tomatoes on May 15th.
Vladimír

[RJGlew]

Hi Vladimir, your planting looks very good. Good luck beating the weather.

[bower]

Your seedlings are looking great! I hope they like their new home, in spite of frosts outside. That would be quite a feat, to have your first ripe on the last risk of frost date!

BTW I have seen quite a few tomatoes set when nighttime temperatures are only 50 F. Only some later season types are more sensitive. So the relative humidity may be the bigger issue, with the early season types you are growing.

Looking forward to see that first ripe in May!

[MrBig46]

We have typical spring weather. At night, temperatures go up to 0 ° C, the sun is shining during the day and the temperature is up to 18 ° C. Leaving the hotbed closed, temperatures go above 50 ° C under sunlight. I can't go to the garden every day. And so on the basis of the weather forecast, differently support the windows so that the temperature difference between night and day is as small as possible. I continuously measure the temperature and humidity and when I go to the garden I take my notebook and download data from the datalogger.
I think I managed to solve the moisture problem.

[asmx91]

It is looking great!!!!

[MrBig46]

This year's tomato season in the hotbed is disappointing for me. I managed to reduce the humidity to a reasonable degree, but the improvement in flower pollination did not. Just like last year, in May, I will only harvest the tomatoes that have developed from flowers pollinated at home in the window. The real harvest will not begin until mid-June.
I was looking for information why this is the case and I found this on the University of Florida website:
Low temperature: Interference with the growth of pollen tubes prevents normal fertilization. The pollen may even become sterile, causing blossoms to drop. Tomato fruit will not set until nighttime temperature is above 55oF for at least 2 nights in a row.
Too bad I didn't know that before. I could have taken some action. There's nothing left for me to wait for one more year. What do I do?
1. As soon as I harvest all the tomatoes, I reconstruct the whole hotbed, mainly adjust the south-facing wall. Under the ground, I will build a wall of heat-storing material (fealite used in electrical storage heaters) and paint it black. Above-ground part of building plywood I lined with polystyrene from outside and painted white from inside. I add a foil to the windows to reduce the heat loss at night.
2. Two of the four windows will install automatic window opening when the temperature rises above 35 ° C. This will make me not to needlessly cool down the hotbed at night and overheat during the day.
3. I install a solar fan in the hotbed.
Vladimír

[xellos99]

Originally Posted by MrBig46

University of Florida website:
Low temperature: Interference with the growth of pollen tubes prevents normal fertilization. The pollen may even become sterile, causing blossoms to drop. Tomato fruit will not set until nighttime temperature is above 55oF for at least 2 nights in a row.

This is not true, my Sungold is setting tomatoes and night temps are between about 39 - 49 all the time 7 days a week.

The 1st one set on May the 4th, when I used a pollination device ( electric toothbrush ) on it and I seen a puff of pollen. A few days later a tomato appeared.

Im positive Gardeners Delight and many of the other varieties I have grown in the last 4 years also set tomatoes well before night time temps are 55 F.

[MrBig46]

I have no reason not to believe the conclusions of the University of Florida. I suppose the research was done on more tomatoes than you and I grow. My experience is in line with the conclusions of this university.
Vladimír

[xellos99]

Originally Posted by MrBig46

I have no reason not to believe the conclusions of the University of Florida. I suppose the research was done on more tomatoes than you and I grow. My experience is in line with the conclusions of this university.
Vladimír

I think they are using varieties that were developed in warmer climates like their own.

I estimate this set when night temps were about 40 F.

tom11.jpg

[bower]

There is a big difference in varieties which are cold tolerant. All the tomatoes I regularly grow will set and grow fruit with night temps of 50 F, as long as day temperature gets to 60 F. Any tomatoes which you know are as cold tolerant as Stupice or Moravsky Div should not need two nights of 55 F to make fruit.
I will just check my data, Vladimir, to see when in the season we have two nights of 55F, because I think by then I usually have a lot of fruit set.


Well, I looked at the data from 4 different years and I can't find any fruit set where there wasn't two nights of 55 F in the time between flower open and set. Bearing in mind it can take anywhere from 8 days and up (typically 15 days but longer in cooler weather) from the time flower opens to the time fruit sets, there were colder nights, even mostly colder nights in the early ones but there were at least two days of 55+ nights in every interval.

So it looks like Florida U conclusion is correct.

[MrBig46]

Tomato fruit will not set until nighttime temperature is above 55oF for at least 2 nights in a row.
It is difficult for me to discuss in English. I understand the University of Florida sharing that the temperature will not rise above 55 ° C for longer time at night. And that was in my hot spot. It can be seen from the measurement chart that ten to twelve hours a day was below 55 ° C in the hot spot. The shorter time was only in the night of 3.4. on 4.4.
That the temperatures at night fall below 55 ° C in May (even several consecutive nights) and the plants set the fruit is nothing unusual. But the text from the University of Florida is not written:
Fruits are not set if night temperature drops below 55 ° F.
I don't know if I wrote it clearly.
Vladimír