Choose a location that receives full sunlight and has good air circulation but is sheltered from the wind. Artichokes need well-drained, fertile soil that retains moisture and has a pH of 6 to 8. The plants have deep, branching roots, so prepare the site by digging 30 centimetres down. Mix a shovelful of compost and organic fertilizer (follow package directions) into the planting hole; water in the seedlings. Keep well watered until established; cover them if frost threatens. Artichokes are heavy feeders, so provide them with another shot of compost and organic fertilizer at the beginning of August.
Space about one metre apart in rows, or use individual plants as highlights in an ornamental garden. Although artichokes reach three metres tall in their native environment, they're usually only about one metre tall in Canadian gardens, with a spread of around two metres.
Mulch initially with a thin layer of straw, hay or shredded leaves to preserve moisture, control weeds and keep soil from becoming too hot. Excessively high soil temperatures may send the plants into summer dormancy. As the plants grow, add more mulch until it's 20 centimetres thick.
Sufficient water is essential for producing tender heads. Water from below, as overhead watering may rot the crown of the plant.
Artichokes are hardy only to about –6°C and have a tendency to rot in wet weather, but given proper care, they'll continue to produce for four to six years, providing a crop of artichokes in late spring to early summer. By overwintering plants and starting seeds early indoors, a double harvest can be enjoyed.
In late fall, cut the plant down to about 15 centimetres above the ground. Mulch with straw, hay or leaves to a depth of 30 to 90 centimetres, depending on the severity of the winter. Covering the pile with plastic sheeting protects against wetness, which could rot the plants, but could also provide a refuge for mice.
In spring, once the danger of heavy frost has passed, uncover the plants and feed with compost and organic fertilizer. Feed again one month later, then in August, as you would with artichokes planted that year.
Additional plants can be produced from overwintered ones. In early spring when the plants are still small (less than 25 centimetres tall), use a serrated knife to separate a rooted shoot from the side of the parent plant. Use a spade to carefully dig out the roots of the shoot, keeping the root ball intact if possible. Plant and care for the divisions in the same way as transplants.
Diseases and Pests
Artichoke plants with plenty of air circulation will rarely have problems; space them far enough apart and keep weeds under control. This should help prevent fungal diseases such as botrytis, a grey mould that attacks leaves and stems. If necessary, remove and destroy diseased plants.
Aphids may be a problem on young leaves and heads. Spray off with a jet of water. If slugs or snails are a problem, handpick, especially after dark or early in the morning.