Saxifraga problems

[Paul T]

And the fact it was a white basalt gravel helped even more, as the white reflected more of the light and heat, thereby keeping the soil cooler too.  So probably not only the gravel, but the colour of the gravel helped.

[Luc Gilgemyn]

Don't worry too much Krzysztof - if it's any consolation, I have a number of S. oppositifolia labels left as silent witnesses of the ones that I lost over the years... 
In my climate - probably a little wetter than yours, but also with the occasional hot spell with temperatures over 30°C for 5 or 6 days or so (not this year !!!  ) - I didn't manage to find a suitable place for them to thrive.  I find them very difficult to please over here... which doesn't mean I won't give them another try in future keeping in mind the new clues I just read from the specialists on this wonderful forum ! 
 

[gote]

It is a long time since I grew Saxifrages with any success. but I learnt a little.
Oppositifolia is not a pot plant. It needs a little space and it needs water.
I would actually try to use very gravelly soil and have some drip irrigation running all the summer.
It is not the sun or heat that seems to be the problem it is lack of water.
Of course I am at nearly 60° North
I found that kabshia saxifrages did best when the pots were constantly watered from below.
A pot on the bench is not the best place in my opinion.
Crevices in the mountains often carry water from glaciers.
Good luck
Göte in mid Sweden. 

[hadacekf]

Krzysztof,
The culture of alpine plants in the garden is wonderful. But some kinds are difficult in some garden. I tried many methods out in many places in my garden.
I am trying after 50 years still!
Look at the pictures. The Saxifraga oppositifolia grow 10 cm far away and have the same soil, stone and sun.
By the way. One alpine plant is a problem plant!

[David Nicholson]

Franz, you are a very wise man.

[Lesley Cox]

Franz, I don't believe the lower plant is yours. You must have photographed it somewhere else.