Size is not important but the vegetable should be compact, plump and feel heavy in the hand. It should be firm and the outer parts should be flexible.

The leaves should break off cleanly and exude small beads of liquid. Not to be confused with the Jerusalem artichoke.
 

It can be kept whole for several weeks in the crisper of the refrigerator, preferably with their stems still attached to keep them fresh.

The hearts freeze well. It is recommended that they be blanched for one minute or soaked for a few minutes in water to which lemon juice or salt has been added, as well as a spoonful of vinegar to keep them from darkening.

Once cut, the artichoke should be eaten quickly since it has a tendency to oxidize even when tossed with lemon juice. It may also produce toxins which produce flatulence.

Hint: to keep artichokes, place them in a vase with their stems in water to which you've added a little sugar. Besides being decorative, they'll stay fresh for 4-5 days.