Some info on the material to be used.

The colour change dosent happen until it reaches 27degrees, 

so physically blowing on it will not bring about colour change.

I can use a conductive thread which heats up.

If I mix thermocromic blue with a normal red to make purple, 

as the petal is heated up through the conductive thread the blue will disapear leaving the colour red.

So I should use a fabric with the conductive thread.

I will need power to heat the thread and change colour and a motion sensor to open petals.