Native to southern Mediterranean region. In west coast zones 8, 9, 14–24, grow artichoke as dependable perennial crop. In Southwest desert Zones 11–13, it is usually treated as an annual and planted in fall for spring harvest, but may hang on to be a perennial. In Zones 4–7, plant in spring when offered and hope for the best–you will get foliage, probably flowers, and a crop if you're lucky. And on the eastern seaboard, you may succeed with artichokes grown as annuals: start seed 8 to 12 weeks before last frost; set outdoors when soil has warmed and frost danger is past.
Artichoke is a big, coarse, ferny-looking plant with an irregular, somewhat fountain-like form to 4 ft. high, 6–8 ft. wide. Leaves are silvery green. Big flower buds form at tops of stalks: these are the artichokes you cook and eat. If not harvested, buds open into spectacular purple-blue, 6-in., thistle-like flowers that can be cut for arrangements (cut them just before blooms are fully open).
In Zone 17, where it is grown commercially, artichoke can be both a handsome ornamental plant and a producer of fine, tender artichokes from early fall to late spring. In Zones 8, 9, 14–16, 18–24, in partial shade, the plant grows luxuriantly at least from spring through fall; edible buds come as a dividend in early summer only.
Plant dormant roots or plants from containers in winter or early spring. Set root shanks vertically, with buds or shoots just above soil level; space 4–6 ft. apart in a full sun location. Where roots are not available or in cold-winter areas, you can grow artichokes from seed. 'Imperial Star' produces the first season (150 to 180 days from seed to harvest) and can be grown as an annual; 'Green Globe' is ready to harvest the second summer after seeding. Start seeds indoors 8 to 12 weeks before last frost; set transplants outdoors in a sunny area when the soil has warmed and frost danger is past, spacing them 4–6 ft. apart.
After active growth starts, water plants thoroughly once a week, wetting the entire root system. If grown only for ornamental value, artichokes can tolerate much drought, going dormant in summer heat. Control aphids; after buds start to form, just use strong jets of water to blast off aphids. Also keep snails, slugs, and earwigs away from plants. For gopher control, plant in raised beds lined with hardware cloth at the bottom or in large containers.
Harvest buds while they are still tight and plump. To encourage a second crop, cut off main stalk an inch above ground after harvesting the last bud of the first crop; new sprouts at base will grow faster and produce sooner than an uncut plant would. In all recommended climate zones, cut off old stalks near ground level when leaves begin to yellow. In cold-winter regions, cut tops to 1 ft. in fall, tie them over root crown, and mulch heavily to protect from frost.
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