Cardoon (Cynara cardunculus var. cardunculus)

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Native to the western and central Mediterranean region where it is mostly cultivated, cardoon is a close relative to the globle artichoke (Cynara cardunculus var. scolymus)–of which it is a cultivated form–belonging to the sunflower family. It still occurs as a wild plant in some parts of the world, and is also considered a weed. Unlike the globe artichoke, cardoon’s blossoms are not eaten and are mostly selected for their stalks (blanched to reduce their bitterness), which are often used as a celery substitute.

Cardoons contain cynarin, a bitter-tasting compound found in the leaves that have certain medicinal properties, improving liver and gall bladder function, stimulating the secretion of digestive juices (especially bile) and lowering blood cholesterol levels.

Growing recommendations

Cardoons are perennial plants, often treated as annuals when harvested during the winter months and eaten for consumption. They require a long, cool growing season, prefer full sun, and do not perform well in shaded areas. The plant is suitable for light (sandy), medium (loamy) and heavy (clay) soils, mostly moist. Cardoons can, to a certain extent, tolerate drought. They grow in soils with a somewhat neutral, mildly acid, mildly alkaline pH. While cardoons can tolerate strong winds, they do not withstand maritime exposure.

Cardoons can be started early spring in a greenhouse, with germination being usually quick. The seedlings can be planted into individual pots as soon as they are large enough to handle, then transplanted in their permanent location during the summer. Direct sowing at a 2 cm depth is also an option and can be done around April. Cardoons meant for seed production should be thinned out to 60 cm. Alternatively, the plant’s suckers can be divided at the same period then planted directly in the garden.

Pollination, crossing, and isolation

Cardoons are in flower from August to September, with the seeds ripening from September to October. The species bears self-sterile hermaphrodite flowers (individual florets combined into a bluish-purple capitulum), having anthers that release pollen five days before the stigmas are receptive. Being allogamous, each floret needs to be pollinated by insects with the pollen of another floret located on the same capitulum or another one in order to produce viable seeds. As cardoons varieties will easily cross with each other as well as artichokes, isolation is required whenever two or more varieties are grown simultaneously. To prevent pollen contamination, the plants’ blossoms can be bagged and shaken once a day to encourage the pollen reaching and fertilizing the ovule. The capitula are cut when they are fully open and exhibit their white seed plumes.

General seed saving guidelines (harvesting and processing)

The harvested capitula can be dry away from sunlight and finish maturing in a protected location. Once they are completely dry, those can be placed inside a bag and strongly beaten with a stick. This will release and separate the seeds from the rest of the flower head, allowing the seeds to be processed easily. They can also be separated by hands (wearing gloves) by rubbing each capitulum over a bowl. Larger debris are removed manually while the remaining chaff is winnowed.

Cardoon seeds will remain viable for an average of seven years when stored under optimum conditions.