Asclepias tuberosa

Eryngiums are very robust plants that grow well in full sun and can be tolerant to drought. The plants bear spikey cone-shaped flowerheads in blue and silver-grey tones. Spent flowerheads give winter interest to your border, so don’t cut them back straight away.

This lovely cottage garden plant has spikes of purple-eyed white flowers that shoot up from glossy dark evergreen foliage. Flowers emerge from early summer and bloom right the way until early autumn. This plant is a biennial, so avoid cutting back spent flowers to allow them to self-seed.

Cobalt blue flowers that resemble butterflies emerge in summer and last all the way into autumn. The plants can cope with light frosts but might need extra protection during extreme cold temperatures. Cut back in late summer to encourage a second flush in autumn and then trim the following year in spring to strenghten new growth.