Seed varieties found in this category are great for annual cultivation, and produce well in their first year. If the seedlings become root bound, transplant to a 3- … Artichoke is considered to be one of the ultimate vegetables. At 3 to 4 weeks, feed seedlings with a weak solution of diluted fertilizer. Sow seeds ¼ inch (.6 cm) deep in a rich starting soil. Provide seedlings with 16 hours or less of quality light for optimal growth. For successful cultivation, follow these Imperial Star artichoke care steps: Start Imperial Star artichokes indoors 8 to 12 weeks before the final frost date. How to Grow an Imperial Star Artichoke. Imperial Star In colder areas with severe winters, you should grow Artichokes as annuals. Maintain ambient temperature between 65- … Germination time for Imperial Star artichoke plants is 10 to 14 days.