2 years ago I saw a Hibiscus heterophyllus var. rosea in flower for sale. The flowers were so nice and large I wanted to try it even if it were rather marginal for me.
Fortunatly the last 2 Winters were mild with only twice minus 3°C, and the Hibiscus was undamaged.
The plant has reached 2,5m high and now is bending with many large flowers.
Does anybody grow it ?