Ideal conditions for growing these flowers, especially in fast draining pot culture ,is somewhere in your garden that has sight of early and late sun.ie open to East and West ,but shaded from the South during the hottest months.Shelter in the spring from killer easterly winds complicates, but short time windbreaks will suffice.Heavy fleece for example.
The important thing is for dappled shade in the hottest part of the day.
If you can combine apple trees ,with fruit, a James Grieve, in this case and a Charles Ross so much the better, but the pansy tribe prefer it seems, the cool wet conditions of perhaps the north much more than the sunny south.Violas seem,because perhaps of many roots to cope a little better in hot conditions.Pansy’s with one or very few tap type roots soon give up.
Some growers place the pot containin the plant into an another pot to reduce the heat warming up the confined roots to damage levels.This could be applied to other pot plants as well.
As in many things in horticultural life we cannot always have conditions that might be considered perfect ,and the challenge is to overcome such situations-so do not despair .