50x Large-flowered Crocus Crocus grandiflorus - Mix 'The Happiest'One moment there's nothing to be seen, the next your garden is full of colour and warmth! The large flowered crocuses (Crocus grandiflorus) are very easy to look after. We love them. The crocuses have even more impact if they are planted in large swathes. Plant the tubers in the autumn. In well drained soil. The flowers bloom in the spring. The tubers can be planted in open ground or in a pot. Potted tubers aren't frost hardy, so bring the pot indoors