If you’re looking for a bold, edible plant to include in your farm’s garden, look no further than the cardoon (Cynara cardunculus). Though growing cardoons is easy and the plants are super-cool looking, harvesting and eating them isn’t exactly a walk in the park. The plant is covered with spines, but the effort is worth it because the flavor is surprisingly divine.
I. Appearance and Characteristics
The cardoon (Cynara cardunculus ), also called the artichoke thistle, is a thistle in the family Asteraceae. It is a naturally occurring species that also has many cultivated forms, including the globe artichoke. It is native to the Mediterranean region, where it was domesticated in ancient times and still occurs as a wild plant.
The wild cardoon is a stout herbaceous perennial plant growing 0.8 to 1.5 m (31 to 59 in) tall, with deeply lobed and heavily spined green to grey-green tomentose (hairy or downy) leaves up to 50 cm (20 in) long, with yellow spines up to 3.5 cm long. The flowers are violet-purple, produced in a large, globose, massively spined capitulum up to 6 cm (2 in) in diameter.
It is adapted to dry climates, native across a circum-Mediterranea area from Morocco and Portugal east to Libya and Greece and north to Croatia and Southern France; it may also be native on Cyprus, the Canary Islands and Madeira. In France, the frost-tender cardoon only occurs wild in the Mediterranean south (Gard, Hérault, Aude, Pyrénées-Orientales, Corsica). It has become an invasive weed in the pampas of Argentina, and is also considered a weed in Australia and California.
The “giant thistle of the Pampas” reported by Charles Darwin has been identified as cardoon.
II. How to Grow and Care
Sunlight
Whether grown as an annual or perennial, cardoon thrives in full sun with at least 8 hours of direct sun per day.
Temperature and Humidity
While hardy in Zones 7 to 9, it prospers in climates with mild summers and winters, such as the Pacific Northwest. In a hot climate, cardoon is not long-lived. Heat also affects the taste. In hot weather, the stalks become unpalatably bitter but the taste will mellow again as cooler fall weather sets in. Protect cardoon from strong winds by planting it in a sheltered location. Mulch around the base to protect the root from the winter cold.
In climates with cold winters, cardoon is grown as an annual.
Soil and Water
Cardoon is adaptable to a variety of soil types, including sandy soil as long as it is deep and well-drained. Rich, fertile soil high in organic matter with a pH of 6.5–7.0 is ideal. Liberally adding compost, well-rotted manure, or other materials before planting will help produce bigger, healthier cardoon plants.
Because of its impressive taproot, cardoon is quite drought-tolerant. However, if you grow it as an edible, make sure it receives a constant supply of moisture. Under drought stress, the leaves and stalks become pithy and inedible.
Fertilizing
Use a granulated all-purpose fertilizer for vegetable gardens and follow the dosage and frequency directions for annual or perennial crops.
Planting Instructions
Start cardoons from seed indoors 6 to 8 weeks before the last average frost date in your area. Fill 4-inch pots with damp potting mix and plant 2 to 3 seeds in each pot, ¼ inch deep. Keep the pots at a room temperature of around 70 degrees F during the day and slightly cooler but not below 60 degrees at night. Spray the soil with water to keep it evenly moist. Once the seedlings emerge, they will need plenty of sunlight or grow lights, otherwise, they will get leggy. Thin to 1 plant per pot and remove the weaker seedlings, cutting them at the soil level.
Harden off the seedlings and transplant them in the garden after the danger of frost is past. Space plants 2 to 3 feet apart.
Pruning
Prune damaged or diseased leaves any time. It is a good idea to remove the dead foliage that covers the ground around the plant, especially if it smothers surrounding plants. As new foliage emerges from the center of the plant, cut off the older, larger leaves to maintain a more vase-shaped plant.
Perennial cardoon dies back to the ground during the winter. In the spring, remove the debris to make room for the new growth.
Propagation
Cardoons are mostly propagated from seed as described under planting instructions above. Collecting seeds from your own plants is best if it is the species and not a cultivar, as those seeds won’t produce plants that are true to the parent. For cultivars, it is best to purchase seeds from a seed company.
Potting and Repotting
Due to its long taproot, growing cardoon in containers is not ideal, especially if your climate is mild enough to grow it as a perennial over several years. Also, the considerable height of the plant makes it likely to topple over.
If you want to grow it as an annual, use a container 1 to 2 feet in diameter and with large drainage holes. Keep in mind that potted plants need more water and fertilizer than plants in the landscape.
Pests and Diseases
Cardoons are prone to be attacked by Japanese beetles and attract aphids, snails, slugs and blackflies. Powdery mildew is a common late-summer occurrence. More serious potential plant diseases, though rare, include gray mold and root rot, which is often caused by wet, poorly draining soil.
III. Types of Cardoon
- ‘Porto Spineless’
This cultivar is grown for its culinary use but the attractive sharply lobed and serrated silver-green leaves are also used for flower arrangements. The stalks of this variety have been bred to have significantly fewer spines than the species. Zone 6 to 10 .
- ‘Gobbo di Nizza’
The name of this rare Italian heirloom variety of culinary cardoon means “hunchback of Nice.” It has thick, almost spineless stalks and grows 6 feet tall with the flower heads so it may need support. Zone 6-10.
- ‘Tenderheart’
Grown mostly for its stalks but, with its large grey-green serrated leaves, this variety also doubles as an attractive ornamental. As a perennial, it grows over 7 feet in height so it may also need staking. Zone 8-10.
IV. Uses and Benefits
- Ornamental uses
Cardoon is an interesting and rather niche perennial typically grown for its silvery color and thistle-like foliage. It can make quite a dramatic addition to cottage gardens or borders and attracts a good amount of wildlife for natural gardens. Cardoon keeps an interesting appearance throughout the winter as well, which could add some nice shape to a usually barren winter area. Euphorbia dulcis ‘Chameleon’ and Ipomoea batatas ‘Blackie’ make for striking companion plants.
- Culinary uses
While the flower buds can be eaten much as small (and spiny) artichokes, more often the stems are eaten after being braised in cooking liquid. Cardoon stems are part of Lyonnaise cuisine (e.g. gratin de cardons). Only the innermost, white stalks are considered edible, and cardoons are therefore usually prepared for sale by protecting the leaf stalks from the sunlight for several weeks. This was traditionally done by burying the plant underground, thus, cardoon plantations in Spain are often formed by characteristic earth mounds surrounding each plant, the earth covering the stalks. In modern cultivation, the plant is usually instead wrapped in black plastic film or other opaque material.
The flower buds of wild cardoons are still widely collected and used in southern Italy and Sicily. In Spain and Portugal, the flower buds are also employed in cheesemaking: the pistils of the cardoon flower are used as a vegetable rennet in the making of some cheeses such as the Torta del Casar and the Torta de la Serena cheeses in Spain, or the Queijo de Nisa and Serra da Estrela cheeses in Portugal. Cardoons were also said to have been used by the Romani or “gypsies” and this would make sense as their encampments would often be situated near sources of water. The vegetable was free for the picking, and could account for the widespread use of the plant. That part is speculative.
Cardoon leaf stalks, which look like giant celery stalks, can be served steamed or braised, and have an artichoke-like flavor with a hint of bitterness. They are harvested in winter and spring, being best just before the plant flowers. In the Abruzzo region of Italy, Christmas lunch is traditionally started with a soup of cardoon cooked in chicken broth with little meatballs (lamb or, more rarely, beef), sometimes with the further addition of egg (which scrambles in the hot soup – called stracciatella) or fried chopped liver and heart.
The cardoon stalks are considered a delicacy in Spain, particularly in the northerns regions of Navarre and Aragon, where they are grown in large quantities. In Spain, cardoons are typically cooked by first boiling the stalks to soften them, and then adding simple sauces such as almond sauce or small amounts of jamón; they are sometimes combined with clams, artichokes, or beans as well.
Because of their seasonality (from November to February), cardoons are a staple of the Christmas dinner in Navarre and the surrounding regions; for the same reason, cardoons are often sold as vegetable preserves, usually in water or brine, so that they can be eaten all year round. Cardoons are an ingredient in one of the national dishes of Spain, the cocido madrileño, a slow-cooking, one-pot, meat and vegetable dish simmered in broth.
In the US, it is rarely found in conventional grocery stores but is available in supermarkets that cater to largely Italian and European neighborhoods in the mid Atlantic states, as well as some farmers’ markets in the months of May, June, and July. As suggested above, they become available in the late autumn near Thanksgiving and Christmas. The main root can also be boiled and served cold. The stems are also traditionally served battered and fried at St. Joseph’s altars in New Orleans.
Cardoons can also be found in their “wild” state, on the banks of streams and rivers, and even drainage ditches on the sides of roads in rural areas. These plants look little like the cultivated variety found in stores. They have many thin stems with broad broad leaves at their ends. There is a reddish color on the stems which grow tough, hollow and inedible as they age. The wild ones are picked in the spring and early summer. To use them, the leafy part should be removed, and the stems cleaned of “stringy” fibers. This cleansing will stain the hands black, and so many people didn’t want to prepare them (Source: Sicilian grandmothers born in Italy in the 1890’s).
Cardoon is one of the herbs used to flavour Amaro liqueur, which may be called Cardamaro.
- Other uses
Cardoons are used as a vegetarian source of enzymes for cheese production. In Portugal, traditional coagulation of the curd relies entirely on this vegetable rennet. This results in cheeses such as the Serra da Estrela and Nisa.
The cardoon is also grown as an ornamental plant for its imposing architectural appearance, with very bright silvery-grey foliage and large flowers in selected cultivars.
Cardoon has attracted recent attention as a possible source of biodiesel fuel. The oil, extracted from the seeds of the cardoon, and called artichoke oil, is similar to safflower and sunflower oil in composition and use. Cardoon is the feedstock for the first biorefinery in the world converting the installations of a petrochemical plant in Porto Torres, Sardinia, providing biomass and oils for the building blocks of bioplastics.
- Medicinal uses
Beyond its edibility, growing cardoon may also be used as a medicinal plant. Some people say it has mild laxative qualities. It also contains cynarin, which has cholesterol-lowering effects, although most cynarin is garnered from the globe artichoke due to its comparative ease of cultivation.
V. Harvesting and Storage
Other artichoke thistle info reinforces the cardoon size; it is much larger and hardier than globe artichokes. While some people eat the tender flower buds, most folks eat the fleshy, thick leaf stalks, which require plentiful irrigation for healthy growth. When harvesting cardoon leaf stalks, they need to be blanched first. Strangely, this is done by tying the plant into a bundle, wrapping with straw, and then mounded with soil and left for one month. Cardoon plants being harvested for culinary purposes are treated as annuals and are harvested during the winter months– in areas of mild winters, from November to February and then re-sowed in early spring.
The tender leaves and stalks can be cooked or eaten fresh in salads while the blanched portions are used like celery in stews and soups. The wild cardoon’s stem is covered with small, almost invisible spines that can be quite painful, so gloves are useful when attempting to harvest. However, a mostly spineless cultivated variety has been bred for the home gardener.
