PlantFiles: Cardo Santo (Holy Cardoon)
Argemone hunnemannii

This beautiful Prickly Poppy is classified as an annual, but I have seen it grow as short-lived perennial many times. It is a very fast growing plant that will benefit from deadheading for a long blooming season. Full sun, well-drained soil and little water are the main requirements of this plant.

Sowing recommendations: regular spring sowing in a mix of equal parts of compost, sharp river sand and regular garden soil. Direct sowing is also possible.

If you leave a few seedpods (leaving all could make them become invasive, although they are easy to remove) on the plant, it will reseed easily and will spare you the sowing procedure. You can pick the plantlets and move them to another location without any fear of damaging them.

CHILEAN PRICKLEY POPPY
This species,which surprisingly is not in cultivation,is unusual in being the only South American prickley poppy with white flowers.It is confined to Chile at rather low altitudes- at least it has not been recorded much above 600 m (2000 ft)
A, hunnemannii clearly comes close to A. polyanthemos in general appearance and differs primarily in its larger buds (18-28 mm or 3/4-1 1/8 in. long as opposed to 15-22 mm or 3/5-7/8 in.) and flowers that are often 10-12 cm (4-5 in) across.The armature of the fruit-capsule is clearly different; in A. hunnemannii the spines are spreading to erect and rather slender,whereas in A. polyanthemos they are stouter,spreading or often somewhat recurved.

P 219, "Poppies. The poppy family in the wild and in cultivation". Christopher Grey-Wilson. Timber Press. ISBN 0 88192 503 9