Imperial Star artichokes were originally developed to meet the needs of commercial growers. This thornless variety of artichoke is primarily cultivated as an annual and harvested during the winter months. In California, where the bulk of commercial artichoke production is located, perennial artichokes are harvested from spring through fall. The introduction of the Imperial Star artichokes allowed California growers to supply fresh artichokes year-round.
Imperial Star Artichoke Info
Since Imperial Star artichokes were specifically bred for cultivation as a cold-climate annual, this variety is well adapted for home gardeners who are unable to grow artichokes as perennials. The key to producing buds on annuals is exposing the Imperial Star artichoke plant to nighttime temperatures in the 50- to 60-degree F. (10 to 16 C.) range for a minimum of two weeks.
Imperial Star artichoke plants typically produce one to two primary buds up to 4 ½ inches (11.5 cm.) in diameter. In addition, five to seven smaller secondary buds will form. Mature buds are slow to open. Their flavor is sweet and mild.
How to Grow an Imperial Star Artichoke
For successful cultivation, follow these Imperial Star artichoke care steps:
- Start Imperial Star artichokes indoors 8 to 12 weeks before the final frost date. Sow seeds ¼ inch (0.5 cm) deep in a rich starting soil. Maintain ambient temperature between 65- and 85-degrees F. (18 to 29 C.). Germination time for Imperial Star artichoke plants is 10 to 14 days.
- Provide seedlings with 16 hours or less of quality light for optimal growth. At 3 to 4 weeks, feed seedlings with a weak solution of diluted fertilizer. If the seedlings become root bound, transplant to a 3- to 4-inch (7.5 to 10 cm.) pot.
- Harden off seedlings prior to transplanting in the garden. Artichokes prefer a sunny location, good drainage and fertile soil with a pH range between 6.5 and 7. Space plants 3 to 4 feet (1 m.) apart. Be sure to expose artichoke plants to cool nighttime temperatures to ensure the production of buds the first year.
- Artichokes require a minimum of 1 inch (2.5 cm.) of rain per week. Supply supplemental water as needed to maintain soil moisture. Mulch to prevent weeds and evaporation.
Harvest artichokes when the buds reach 2 to 4 inches (5 to 10 cm.) in diameter. In comparison with other varieties, Imperial Star artichokes are slow to open. Over mature artichokes become too fibrous for consumption, but left on the plant the buds open to reveal attractive, thistle-like flowers!