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Lauritzen Gardens
October 03, 2004
Cynara cardunculus

Cardoon is a clump forming tender perennial with pinnatifid (spiny) silver gray leaves that develop up to 20 inches long. Purple, 2 to 3 inch flower heads will develop throughout the summer growing season.

They were first cultivated as a vegetable by the French and said to have been brought to America in the 1790s by the Quakers. A relative of the artichoke, the growing characteristics and requirements are similar. However, instead of eating the flower heads, like you do with an artichoke, the thick, fleshy leaf bases, hearts and roots are eaten.  They have a slightly spicy, celery-like flavor.




With a bit of care, the plants will remain productive for 5 to 7 years in zones 8-10. The plants can grow over 7 feet tall and make an interesting and attractive addition as an edible ornamental in your beds and gardens.  They should be wrapped in paper and have dirt mounded around them to over winter in cooler climates. Harvest is enjoyed beginning in late spring to early summer.

Start them as seedlings indoors. The seedlings, when first planted out, want to see about 8 to 10 days of temperatures around 50° if they are to have a good growth; hereabouts, that means planting out in mid-March or so.  Since they require a good 6 to 8 weeks indoors as seedlings before being set out, we should sow seed around mid-January.

Starting Seedlings

Sow your cardoon seeds about ¼ inch deep and ¼ inch apart in a lightly moistened soil-less growing mix. Use a good-quality starting mix, not hardware-store "potting mix": you want a soil-free medium, to be sure there are no fungal problems ("Jiffy Mix" and "Pro-Mix" are representative examples of the sort of thing wanted, and many mail-order garden-supply houses have a proprietary mix). Germinate the seed at a temperature of about 75° F.: heating pads or the like under the seedling flat or pot are an immense assist to good germination. Be sure to start more seeds than you want plants, perhaps half again as many, because you will likely have to cull them at planting-out time.

As soon after emergence as the individual seedlings can be handled, transplant them into fair-sized pots or cells--say 2 to 4 inches in size. Keep those transplants growing at temperatures as close as you can get to 65° in the day and 55° at night; the day and night temperatures can be plus or minus 5 degrees, but try to keep the day/night difference at around 10°.

When the outdoor daily highs hit the high 40s, transplant your seedlings out.

The Bed

Site your cardoon bed where the plants will get at least 6 hours of sun, as they will not develop properly without it.

Cardoons need really good soil to thrive. Before planting out your seedlings, spade the ground deeply (well-drained soil is important), and supply it with good compost or manure (and fertilize again, generously, every season). If your soil is heavy (clay), work humus or even sand well into it. Slightly acid soil is wanted for cardoons--some say even as acid as pH 6.0 (though others say 6.5).

Transplanting Out

We have seen spacing recommendations from up to six feet down to 18 inches, which makes selection problematic. The optimum will depend in part on your soil: the better it is, the bigger the plants will grow. A test planting at small spacing, especially in a deep-dug bed, seems logical, because you can just pull out some if the lot is getting wildly overcrowded. But in an event, this vegetable will eat up garden space.

Cardoons may not always grow true to type from seed (they are commonly propagated by cuttings); cull your seedlings before you transplant: look for stunted or albino types and discard them.

We want to plant cardoons out when they can get their first days at around 50° or so, but, around here anyway, that can expose them to freezes--our typical nightly lows in mid-March are skirting the freeze line--which they should not see. It thus seems wise to provide the seedlings with some early night-time frost protection for their first couple of months. Take care! Do not expose the plants, especially at first, to daytime temperatures warmer than the ambient. That means not just setting something like a Wall o'Water on the seedlings and leaving it there. One approach is to fill a number of transparent or translucent plastic soda or milk jugs with water and leave them in the sun during the day somewhere away from the cardoon seedlings, then move the jugs around the plants at night so the accumulated heat in the water softens the night-time lows for the seedlings. (Moving Walls o'Water around on a twice-daily basis would be far too tiresome.)
Cardoon --October 03, 2004
Lauritzen Gardens


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