Plumbago Large clusters of deep blue flowers, make this a tough and hardy plant. Grow it over a fence or plant a row for an informal hedge. Plant into well conditioned soil with water crystals and controlled release fertiliser added. Drought tolerant and frost hardy. Position: Full sun (its REALLY drought tolerant and tough!) Prune after flowering to control shape. Forgetting to prune may lead to an overgrown shrub. Otherwise pest and disease free!