Some munstead lavender has changed from a blue/purple flowers to a white flower over the winter. Last spring they bloomed blue. Now this spring 3 of them are blooming white. I can not find a reason for the blooms to change color over the winter. Is there some kind of mineral or something that gives them the blue color? Do growers give them some chemical to make them grow bluer than normal? I still have 2 that are blooming blue, think they will change white next spring? I don't really want a white, blue, white, blue, white lavender hedge, which is what I have now.

Just as a background on them, they were left over from landscaping at my work. They were left over winter in the pots, and the snow from the parking lot was all pushed on them. Come spring I took them and planted them. They grew and bloomed blue. That fall I moved and transplanted them to my new home. They are growing and look healthy. So admittedly they have had a hard life could that change the bloom color?