The Globe Artichoke (Cynara cardunculus var. scolymus) is a thistle-like plant cultivated for its immature flower bud. This edible portion is a large, unopened bloom that is commonly harvested and cooked. If the plant is allowed to mature, the bud opens into a large purple flower where the seeds are eventually produced. Understanding the appearance of these seeds is essential for propagating this perennial vegetable.
Identifying Artichoke Seeds
Artichoke seeds are relatively large, measuring about five to seven millimeters long, similar in size to a small sunflower seed. Their shape is distinct, typically described as oval or an elongated wedge with a slightly pointed end.
The seeds are generally dark, ranging from deep brown to almost black, with a firm and smooth surface. Some varieties may feature a mottled appearance or faint ridges along the shell. A key identifying feature is the presence of a small, fluffy tuft of fine down attached to one end, which assists in wind dispersal.
Viable seeds are not found in the tender, immature flower bud purchased at the grocery store. Seeds only develop within the mature, fully opened flower head after it has dried on the plant. If the flower bud is not harvested for consumption and is allowed to bloom, the plant produces the seeds needed for propagation.
Preparing Artichoke Seeds for Growth
Since artichokes do not always grow true to type when self-pollinated, it is recommended to purchase seeds from a reputable supplier. Successful germination often benefits from cold stratification, a technique that mimics the natural winter rest period. This cold treatment helps break seed dormancy and signals that conditions are favorable for growth.
To stratify the seeds, store them in a refrigerator for a few weeks in a damp medium like sand or peat moss before planting. Once stratified, sow the seeds about a quarter-inch deep in a seed-starting mix indoors, eight to ten weeks before the last expected frost. Germination is best when the soil temperature is kept warm, ideally between 70 to 75 degrees Fahrenheit (21–24°C).
Seedlings emerge within 10 to 20 days and require consistent moisture and plenty of light to develop into sturdy transplants. Young artichoke plants also need a period of cool temperatures, known as vernalization, to encourage the production of the edible flower buds. This secondary cold exposure is provided to the established seedlings before they are planted outdoors.