Hello Lawrence. I can only tell you what I do for Dionysias and similar. This may differ from the experience of others since it does depend on various factors such as compost, frequency of repotting, type of plant. I think most would agree that the most important would be to restrict the use of Nitrogen to the point of total elimination unless a plant has not been repotted for some time. In the past I have used liquid Potassium which I used to get from Viresco. More recently I have used Chempak 0-10-10 and in an emergency tomato fertiliser. Be circumspect with the dilution rates. In general I don't water my plants directly, just through the plunge; but when applying the above, perhaps two or three times a year in winter/early spring this is done inside the perimeter of the pot. One note of caution if you have aluminium staging is that tomato fertiliser will produce a chemical reaction with the aluminium which can lead to pitting or in severe cases holes.
Good luck with the showing
Paul
