How to Grow Artichokes as Annuals

Purchase artichoke seeds from a local gardening center or order them from a reputable seed company. Recommended varieties to grow as annuals include Imperial Star, Emerald and Green Globe. Do not use seeds stored longer than 6 years as they may not germinate. Note that artichokes grown from seed do not always come true to type, so purchase more than you think you will need to compensate for this.

Sow artichoke seeds about 1/4-inch deep in seed trays filled with potting compost. Water lightly but frequently, just enough to keep the soil moist. Seeds should be sown around 8 weeks prior to the last frost date. Keep the seed tray in full sun inside a heated greenhouse or on some other device such as a heat pad in a sheltered environment. Ideal temperatures for seed germination are between 70 and 75 degrees Fahrenheit. Transfer seedlings to larger pots once several true leaves begin to form. These seedlings require at least an average temperature of 60 degrees Fahrenheit.

Transfer plants to their permanent growing places once temperatures average between 40 and 50 degrees Fahrenheit. Space plants 2 to 3 feet apart in rows at least 3 feet apart. Protect them with a cold frame or cloche for at least two weeks. This adjustment period is necessary for successful growth. Young artichokes are tender to frost, so keep an eye out for late frosts and cover them again if necessary.

Harvest artichokes in late summer or early fall once immature buds begin to form, typically an average of 90 days after sowing. Buds will be plump and firm. Continue to harvest until hard frost kills the plant. Buds will blacken and become inedible when this occurs. If allowed to flower, the plant also becomes inedible, although many gardeners find the blossoms attractive and grow them purely for added ornamental value in the flower garden.