Aromagica^® Purple Heliotrope Heliotropium arborescens

I am very disappointed in this new PW Aromagica purple heliotrope. It has stayed only 6" tall, though it was planted in the beginning of March after our last frost date. I garden in very hot zone 9b, in northern California. Last year, the PW Lavender heliotrope that I planted in this spot of all day sun, grew immediately like gangbusters, right after it was planted. It ended the season being 20"x 20", and bloomed for over 5 months straight, with identical care, light, water that the purple ones are now getting. 4 of 5 of the lavender ones came back for me, and I planted the purple ones around them, hoping for a nice two toned effect. Now all the lavender ones are again doing great, already over 14" x 14"and blooming beautifully. Sadly, the purple ones around them look like 6" runts, with sparse blooms, after being in the soil for over 3 months. How can two colors of the same plant, grown in the same spot with identical conditions have such different results? I am wishing I had just ordered more of the lavender heliotrope, and never tried the new purple ones.