I have always been attracted to gigantic perennials to add both structure and architectural interest to our garden. This is true of both the borders and kitchen garden on our property. Two plants that I have constantly returned to when planning spring plantings are the Mediterranean natives, artichoke “Cynara scolymus” and cardoon “Cynara cardunculus”, both members of the thistle family.
These are probably plants that many have not tried to grow locally; however, I have had reasonable success with both. Our kitchen garden is traditional in the sense that it contains both edibles and ornamentals. Artichokes and cardoon fall into this group in more ways than one. Artichokes traditionally are grown for their immature flower heads and cardoon for their tender blanched shoots. Rarely, however, do we eat either. It is here where they provide their ornamental qualities that we crave in the overall garden design.
In a good growing season our plants have yielded a few prized artichokes which are not often picked in order to provide that surprise with visitors to the garden. They truly provide shock value when seen as growing in our climate and not in California! Cardoon plants, as well, elicit curiosity and guests are amazed when they discover they are an edible as well. Our primary purpose in growing both of these garden specialties is in the absolutely spectacular thistle-like flowers and foliage.
Cardoon and artichokes grow stately tall – up to a metre in height and width with their fountain-like bold silvery green serrated leaves. I first came across cardoon when visiting the Niagara Parks gardens where they were planted in large ornamental urns. What a statement and at that time I did not realize what kind of plant it was nor of its flowering nature. I have always had an affinity for unusual plants in the garden especially those of the thistle family. Scotch thistle and Japanese thistle and other plants with similar flower shape can be seen in our borders.
Both artichokes and cardoon are grown in our gardens in full sun, well-drained compost-enriched soil, watered, fertilized and cared for much the same as all plants in our gardens. Pests and disease have not been a problem. If aphids do appear, a strong blast from a garden hose will usually do the trick.
Artichokes grow well in climates with mild winters often lasting for up to 5 years of harvest so obviously I am treating them much like annuals here in Wellington County. Flower buds form atop strong stems and are edible if they are tightly closed. However once they begin to open they are no longer tender but will eventually burst into large bluish thistle-like flowers. These are our prize for growing both artichokes and cardoon. They make striking cut flowers for both indoor and outdoor entertaining.
I have never had success overwintering artichoke plants; however, some varieties are purported to be winter hardy. “Green Globe” and “Imperial Star” have been bred to grow as annuals in our climate. Both can be heavy producers under perfect growing conditions. Each has an early maturity date and thus suitable to be grown as an annual. I have always purchased young plants at garden centres that specialize in herbs and unusual plants rather than grow from seed, however, that would also be an option if sown in late winter.
Cardoon is similar to artichokes in both growing and flowering. Although considered tender perennials, they are much hardier and most often return the following spring given a good winter mulch. Cardoon as well can be planted from seed sown late winter or can as well be found as young transplants at some garden centres. I have even found plants that have been grown on in much larger pots and, of course, a much more commanding price!
Cardoon is enjoying a renaissance and is gaining in popularity as a vegetable that occasionally can be seen at the greengrocers and farmers’ market. The fleshy leaf stalks are blanched by hilling up soil around the stems, tying and wrapping with burlap to about 45 cm high. Trimmed stems are ready after about four weeks and can be steamed and buttered as a side dish. Cardoon are similar in flavour to an artichoke.
So be brave and add some excitement not only your gardens and containers but to your dinner table as well. Happy gardening and Bon Appetite!
— Robert Newman, Guelph-Wellington Master Gardeners