Whether you are into the culinary arts or edible landscapes, you may want to put this plant at the top of your list. Chosen by the Royal Horticultural Society as one of the top plants of the last 200 years, Cardoons are aristocrats in both the ornamental and the vegetable world.
As an ornamental plant it is valued for its striking foliage. With its long, arching, deeply toothed, soft grey-green foliage, Cardoon makes a dramatic statement in the flower border.
In summer, tall flower stems are topped by fat thistle buds which open into large blue-violet or purple blooms which are highly attractive to bees and other pollinating insects. The dead flower-heads can be left on the plants and provide an attractive feature over the winter months.
For the ornamental gardener, their very early production of multiple divided silver foliage is a real boon - in the words of that great writer on perennials, Graham Stuart Thomas, the “grandest of all silverlings”.
Unlike most herbaceous plants, they start to make growth soon after Christmas - sometimes even before. Often the first signs of spring are not just snowdrops and hellebores but these elegantly arched strikingly silver leaves, which stand out so well against the expanses of bare brown soil. There is something so unseasonally lush and sumptuous about them.
Gourmet gardeners ought to include cardoons in their repertoire; it is a close relative of the globe artichoke and just as much of a delicacy. It is difficult, if not impossible, to find them at a greengrocer's. In France, Italy, Spain, and other European countries where the cardoon still thrives, you are likely to find many different dishes. Recipes are everywhere on the Internet.
The tasty stems have an artichoke-like flavour and look like large celery stalks. They are blanched and are delicious steamed or braised. They may be stewed, used in soups, or eaten raw in salads or in a vinaigrette dressing. I am told that the flowers too can be cut and cooked or be dried to use as a substitute for rennet in those dishes requiring curdled milk.
- Awarded the RHS Award of Garden Merit
Cynara cardunculus was awarded the Royal Horticultural Society’s Award of Garden Merit (AGM) in 1993.
It was also chosen by the RHS as one of the top plants of the last 200 years.
Sowing: Sow from January onwards for planting outdoors from the end of May.
Cardoon is grown from seed started in mid winter to late spring. Sow seed into individual small, 7cm (3in) pots and place under glass or in a cold frame (without heat) six to eight weeks before planting in the garden.
Plants grow slowly at first and should be transplanted into a larger container for sizing up before transplanting into the garden as soon as the danger of frost is past.
Transplant into the garden once all danger of frost has passed. Cardoon requires a well-drained, fertile soil and full sun to prosper. Once in the garden they grow fast once the warmth of summer begins.
For Culinary Use:
If planting for edible use, prepare trenches at the same time as planting seeds: The best trenches, they say, will have been dug a month earlier, not less than 45cm (18in) deep with the bottom third being a rich mixture of well-decayed manure and soil. The earlier sowing should provide plants to put out at about the end of May. Plants will establish slowly, and seem not to grow for the first few weeks after transplanting. However, be patient, always watering abundantly, an essential practice to keep the leaf ribs tender
Cardoon is most often used as a bold accent plant in the flower border or even as a specimen plant. It should have plenty of room to spread and not be crowded by neighbouring plants. The plants may require copious amounts of water during the summer, preferably soft water. Mulch the plants to control weeds.
The thistle heads can be cut and used as a cut flower, otherwise they can be removed as soon as the colour fades from the blossom. If the seed heads are allowed to form, small seed-feeding birds such as finches will find their way to the plants and brighten the garden after the flowers have faded from memory.
Cultivation as a Crop:
If you are aiming to producing plants for the cooking pot, feed with a liquid feed which will encourage stem growth without flowers. Blanching removes the bitterness from the leaf ribs, which is the part you eat. To blanch your cardoons, first remove all damaged or rotten leaves. Then bunch the leaves up together and tie them at two or three intervals with soft twine or raffia into a tall cylindrical shape. Wrap this leaf cylinder with burlap, cardboard, or pieces of weed-barrier fiber, tying the covering in place. Otherwise you can form a hill of soil around the stem in much the same way as for celery.
This prevents photosynthesis from taking place and makes the bitter compounds in the leaves disappear. Just a tuft of leaf tips should emerge at the top of the wrapping. During the blanching period, check the plants frequently as they are more susceptible to rotting during this period. If you have grown quite a few cardoons and live in a mild winter area, plan to blanch them in a staggered fashion. Once blanched, they must be harvested.
Harvest the plants four to six weeks after blanching. Cut them off at ground level with a stout knife and trim off the outer leaves. They can be left in the ground but in the event of severe weather it is advisable to lift them for storage. They should then be wrapped in brown paper or black polythene in a box of sand or peat to retain moisture.
The flavour of cardoon is extremely close to that of the artichoke. It marries beautifully with black olives, anchovies, preserved lemons and olive oil, but also with the richer notes of crème fraîche and bechamel sauce. It is best served by itself rather than mixed with other vegetables.
To prepare cardoons for cooking, remove any bruised or ragged outer stems. Remove the leaves from their ribs. Then, using a sharp paring knife, thinly pare the backs of the ribs, removing the tough fibres that run along them. Cut the ribs into two- to three-inch sections and drop them into acidulated water as you work, as cardoon oxidizes only slightly less quickly than artichoke.
Cardoons are plants of Mediterranean origin, which immediately prompts a question: Why are plants from the Mediterranean growing so strongly at low temperatures, when most of our herbaceous plant flora, from much colder climates, is still dormant? The answer lies in the complex relationship between plant life and climate. In a Mediterranean climate, hot summers force many plants into dormancy through drought. With the cooler damp weather of autumn, many annuals germinate and perennials start to grow, and carry on growing through the winter. Their physiology has evolved to avoid vulnerability to their main enemy - summer drought, not winter cold.
The plants resemble precisely those of artichokes, with the most obvious difference being the more deeply dissected, feathery leaf margins of cardoons and, sometimes their more silvery colour. The booms of both plants open into familiar blue thistle blooms.
The genus name Cynara derives from the Greek kyon, meaning ‘dog’, the phyllaries being likened to dogs' teeth.
The species name cardunculus, means ‘resembling a small thistle’
Cynara cardunculus is commonly called Cardoon, Artichoke thistle or Texas Celery
Other language names include: Chardons (French); Kardone (German); Cardi, Carducci (Italian); Cardo comestible (Spanish); Alfcachôfre brava (Portuguese)
- Awarded the RHS Award of Garden Merit
- Additional Information
Packet Size 2 grams Average Seed Count 50 Seeds Common Name Cardoon Family Asteraceae Genus Cynara Species cardunculus Hardiness Hardy Perennial Flowers Fat thistle-like buds which open into large blue-violet or purple blooms Natural Flower Time Late Summer Foliage Long, arching, deeply toothed, soft grey-green foliage Height 120 to 180cm (48 to 72in) Spread 60 to 90cm (24 to 36in) Position Full sun, tolerates partial shade Aspect Some shelter preferred Soil Well-drained, fertile Time to Sow Sow early April onwards for planting outdoors from the end of May onwards Germination 7 to 14 days