Bigleaf hydrangea Hydrangea 'Jewel' Blue-Purple - Hardy plantFlowers that change colour? That's what you can expect from hydrangea 'Jewel' (Hydrangea macrophylla). The 'Jewel' grows blue and green flowers. Over the course of the seasons, the colour changes from blue to purple to deep green. An ever changing appearance! You can plant the hardy hydrangea all year round, provided temperatures have not dipped below freezing. The flowers bloom in the summer. Pruning is not necessary. Unless the bush becomes too