Since 2017, I have been trying to grow determinant tomatoes in my cold frame so that I have the first ripe tomatoes in the second half of May. Every year I planted the seedlings in the last week of March, the plants grew beautifully, they already put on flowers at the end of April, but I could not pollinate the flowers even though I tapped them, reduced the humidity in the cold frame, etc.
The reason was that I never managed to keep the night temperature in that frame above 11°C, which is a necessary condition for the pollen to germinate and pollinate the flowers. The flowers were pollinated only in May, which postponed the harvest of ripe tomatoes by at least a fortnight. That's why I chose parthenocarpic tomatoes bred by Dr. Baggett from the University of Oregon for this year. I already have the seedlings outside the window and they are doing quite well. The picture of the seedlings is from the end of January. This Monday I planted the already grown parthenocarpic tomato seedlings in my deep greenhouse. I hope to be successful this time.
Vladimír

Looking good @MrBig46

Looks great wich variety did you choose ??? There are several I’ve thought about trying and still might
never mind I saw the name haha

I only had the six varieties whose seedlings are in that picture from January. I can't compare yet, only Oroma bloomed outside my window and I planted it already with some fruits (the largest one inch in diameter). But I had a problem with it because it was quite tall and barely fit in my steamer. Cold frame picture of planted tomatoes from Monday.
Vladimír
free screenshot tool

looking good

How many days does it take from seed to flower?

And at what temperatures (day and night) do u ceep the plants?

I grow tomato seedlings for March planting in atypical conditions. I live in a panel house and the only option where I can grow seedlings is a bedroom with a north window, where the temperature is constantly between 17 and 18 °C. Therefore, I have to adapt the sowing date to these conditions, and therefore I sow in the autumn when the days are the shortest. For this year's planting, I sowed on 11/11/2023 and in November and December I lit them a little with 4 hours of LED 23 W. I think I succeeded this year, but I think that the length of cultivation in other conditions will be completely different - certainly shorter.
Vladimír

@MrBig46 Your picture and choices are very interesting. I've never grown Oregon Spring or Siletz. From your picture, they seem more compact, with larger leaves (especially Oregon Spring). Would you say that is accurate (and not due to some other environmental factor such as it having had more light)? I've never been able to get mid-May ripe tomatoes except with micro-dwarfs started around the first week of February. Good luck!

Tomatoes bloom profusely in a deep hotbed. I hope to see some seedless fruits as well. So far, I have harvested only two fruits of the Oroma variety, whose flowers were pollinated at home outside the window (before planting). Of course the fruits the size of a larger cherry had seeds and so I let the seeds ferment. Maybe someday the seeds of this variety will come in handy.
Vladimír