Artichoke ‘Imperial Star’ – an early-cropping variety with large, almost spineless heads.
The large, rounded heads of this open-pollinated variety have fleshy hearts and a pleasantly mild, slightly sweet flavour. With early sowing under cover and a cool development period, the plants can produce a generous harvest in their first year. The large main heads are followed by several smaller side heads, which can be harvested in succession. Unharvested buds open into decorative purple flowers that attract pollinators and can also be used as cut flowers.
Origin & History
‘Imperial Star’ was developed in California through a breeding programme at the University of California. Wayne L. Schrader and Keith S. Mayberry developed the variety specifically for growing from seed with a harvest in the first year. The breeding material originated from progeny of a cross between French and Italian artichoke lines. From 1986 onwards, plants were selected for early maturity, uniform heads and good yields. Further selection up to 1989 established the characteristic glossy, almost spineless heads.
‘Imperial Star’ was documented under its name by 1990 and received plant variety protection in the United States in 1991. The variety made it possible to grow artichokes as an annual crop from seed while producing marketable heads and was trialled both in coastal areas and in the warm inland regions of Southern California. This helped make cultivation outside the traditional perennial artichoke-growing areas more significant. Today, ‘Imperial Star’ is offered as an open-pollinated variety that is particularly valued for its early cropping, making it well suited to gardens with a limited growing season.
Appearance & Characteristics
The vigorous plants form a spreading rosette of deeply divided, dark green to grey-green leaves with prominent pale leaf ribs. Including the branching flower stems, they usually reach around 100–150 cm in height. The larger heads develop at the tips of the main shoots, while smaller heads form on the side shoots. The variety is moderately winter-hardy; overwintering outdoors requires a well-drained site and protection during severe frost.
Bud & flower details:
Size: Large main heads around 8–12 cm in diameter; side heads remain smaller
Shape: Rounded to spherical, with tightly overlapping, almost spineless outer bracts
Colour: Green with a noticeably glossy surface, occasionally slightly purple at the base; open flowers are purple
Texture: Fleshy hearts and bract bases, tender after cooking
Flavour: Mild and aromatic with a slightly sweet note
Usage & Cultivation Highlights
The large heads are suitable for boiling and steaming and can be served whole with a vinaigrette or dip. The tender hearts can also be grilled, stuffed or marinated as antipasti. Smaller side heads harvested young are particularly useful for frying and vegetable dishes. Once prepared and blanched, artichoke hearts can be frozen for storage, while fully opened flower heads add interest to fresh and dried flower arrangements.
One advantage at harvest time is the comparatively slow opening of the outer bracts, which helps the heads remain tightly closed and usable for longer. In mild regions, the variety can be planted in autumn and harvested the following spring. An even water supply during bud development supports the formation of well-filled heads, while prolonged periods of heat and drought can reduce their quality. Depending on the location and cultivation goal, ‘Imperial Star’ can be grown either as an annual crop for harvest or maintained as a perennial.
Compared with other artichoke varieties, the particular strength of ‘Imperial Star’ lies in its reliable first-year cropping when raised early and given a suitably cool development phase. Its large, almost spineless heads, mild flavour and slow-opening outer bracts make it a versatile choice for the kitchen and for gardens where the artichoke harvest should not depend on successful overwintering.
