For the first time, I had flowers on some of my annona seedlings:

annona muricata

annona cornifolia

I had also flowers on my annona scleroderma seedling for the first time.

First crop on my kaki cv. Hana Fuyu tree in pot:

Very nice! Are these hard to grow outside? I've found annona and kaki seeds online but for annona they mention that it might be tricky growing them and when doing a research for kaki I found that it is best to look for a plant which has another kaki rootstock for better resistance against cold.

What do you think about that?

No, those annonas are not frost resistant (tropical or subtropical plants). Only one species in the same plant family - the Annonaceae - asimina triloba (paw paw) can withstand frost in our conditions.
Kakis are questionable - I am overwintering them together with citruses. I now some cases outdoor, but it always risk. It can withstand one winter with some protection and can be killed the next winter.

I see. Thanks for the reply. No annonas nor kaki's for me then :d

Beautiful plants, congratulations!

Eugenia neonitida - Pitangatuba

I think I have a better chance for the kaki's. I thought Slovakia was zone 8 as well. My mistake :d

There are also some hybrids of Diospyros kaki x Diospyros virginiana with higher frost resistance, like

Diospyros virginiana x Diospyros kaki 'Geneva Long'
Diospyros virginiana x Diospyros kaki 'Nikitas Gift'
Diospyros virginiana x Diospyros kaki 'Rosseyanka' etc.

In Europe, kakis are usually grafted onto diospyros lotus rootstocks. They are grafted onto diospyros kaki only in case of incompatibility with d. lotus.

I have read that kakis on diospyros virginiana are short lived.