Last year my hibiscus had pink and yellow flowers. This year I have only gotten the pink ones. Is there a reason for this? Thank-you.
It could be a lack of nutrients in the soil, or that the plant is getting more sun than it did last year. Both of these can influence the vividness of color on the flower. It may also be that the original plant was grafted and the scion (the yellow blooms you saw last year) died and was replaced by the rootstock which produces a different color (pink).