· Stephen Whatley's Answer
· Hi Karen.
I have heard that changing weather conditions have a contributing factor in changing the colors of salvia. Often you hear of the petals losing luster and fading out in situations of prolonged,intense heat. In turn, I have seen cases where rain has played a role. Late day summer showers that last for a brief moment will cause water to bead on the flower petals and act as a magnifying glass. Apon doing so, they will leave spots on the petals and create the allusion of a different color.
It could be genetic mutation. The salvia could be reverting back to the mother plant from which it derived. I have seen this happen on a number of different varieties of plants but, never the entire plant. Usually you will see only one or two blooms that decide play by their own rules.
I personally have not heard of aluminum sulfate being used to change the color of salvia. Salvia does well well with a neutral pH. A level of 7.0 in a pH scale that runs from 0 - 14. In saying that, I feel there would be no adverse effects in at least trying. Salvia is plant that is extremely adaptable to a wide range of pH levels due to its ability to grow in many different zones throughout the country.
I must say this is a question that has really got me thinking. I will discuss this further with my associates to see if I can give a more definitive answer to what could have caused this. In the mean time, if the salvia is all around good health,enjoy it and it's interesting aesthetic value it has presented its self with. I will keep in contact with you and let you know if I come across any further information.
I hope this information helps and please feel free to ask any further question regarding this,or any other matter you may have regarding your landscape.