An update after a long pause. I received a few questions asking me about the progress of my Kratky experiment, and want to apologize for having taken so long to respond.
So here it is in a nuthsell: Despite the mysterious leaf disease, the Kratky tomatoes (grown inside) finally did produce a crop in July. In Late August, when even the last tomatos ripened, I’ve taken the Kratky set-up down till the next growing season. Overall, the experiment was successful and I intend to try it again.
The positives: The tomatos in the Kratky set-up ripened significantly faster than those left in soil on the terrace. In fact some of the tomatos grown conventionally outside have not been harvested till the time of writing this post i.e. October. That is largely due to the fact that I live in a climate which is relatively cold with lots of rain, not ideal for growing tomatos outside. So behind windows with good sun exposure (south-east in my case), one can get fruit with the Kratky method very quickly. In colder periods, I added/changed water about once in two weeks, in the hot spells as the tomatos were ripening, they were able to drink up the whole 8l container in a week! Even that is comfortable compared to the outside soil containers, that needed watering every day.
The negatives: In the end, I haven’t found out what exactly was the cause of the leaf spots. However, I suspect it was some sort of a fungal disease, possible aggravated by lack of air circulation and damp air inside my flat. The plants outside ripened slowly, but suffered no leaf disease at all. Also, the outside plants produced more fruit, probably because of better pollination thanks to wind and insect pollinators, both lacking inside behind the window.
I’ll conclude this post with a photo of a few tomatos from this year’s Kratky experiment (the greens are from the terrace).