Artichoke

Globe artichokes are grown for their edible flower buds, which are picked before the bracts open. The plants look a lot like thistles, with silvery leaves and flower stalks that can reach 5 feet (152 cm) tall if they are left to bloom. They can live for many years in frost-free climates, but they can also be grown as an annual for a fall harvest.

Start seeds indoors about 8 to 12 weeks before the last spring frost. Plant 2 or 3 seeds per cell in 50-cell trays or individual containers, about ¼ inch (0.6 cm) deep. Keep them at 70 to 80 °F (21 to 26 °C) to germinate, and expect seedlings to emerge in 8 to 12 days. Plants need 2 to 3 months to reach transplant size.

Seed results are highly variable and often weaker than the parent plant, so many growers plant root divisions instead. Divisions go in after the last frost, 2 to 3 feet (61 to 91 cm) apart in rows 2.5 to 3 feet (76 to 91 cm) apart. If you transplant seedlings, space them 18 inches (46 cm) apart in rows 2 to 3 feet (61 to 91 cm) apart. Plant 3 to 4 weeks before the frost-free date for your area.

Artichokes need full sun and rich, well-drained soil with plenty of organic matter worked in before planting. A soil pH between 6.5 and 8.0 suits them. Plants need cool spring weather to start flower stalks, so planting too late can stop them from flowering. Cold exposure of about 10 days at 35 to 50 °F (2 to 10 °C) can help first-year plants flower.

Watering. Water 1 to 2 inches (2.5 to 5 cm) per week, in several sessions, and use drip irrigation if you can. The shallow roots do not tolerate hot, dry conditions.

Mulch and feeding. Mulch 2 to 3 inches (5 to 8 cm) deep with compost or straw to hold moisture and reduce weeds. One approach is to apply 2 teaspoons per plant of a 21-0-0 nitrogen fertilizer every 4 weeks, starting 4 weeks after transplanting. Another approach is a low-nitrogen fertilizer high in phosphorus and potassium, worked in before planting.

Dividing. Divide the plants about every 3 years to keep them productive.

Aphids are the main pest mentioned. A strong stream of water can knock them off the plant. Fungal root rot lowers plant vigor, turns leaf tips yellow, and can kill plants; stress from overwatering, drought, over-cutting, and weeds raises the risk. Viruses spread by aphids cause plants to decline, so controlling aphids also helps prevent them.

Harvest usually begins in late July or early August and continues until frost. Cut buds at full size, before the bracts open, leaving 2 to 3 inches (5 to 8 cm) of stem. Buds left on the plant open into purple, thistle-like flowers.

Harvested buds keep for 3 to 5 days in the refrigerator. After several frosts, cut back the leaves and mulch the roots heavily for winter. In colder areas, dig up the plants and store them in moist sand or peat in a cold cellar, then divide and replant the roots in spring. Cutting plants back to 12 inches and covering them with leaves helps them overwinter.

Handling the plant may cause contact dermatitis, a skin reaction. The page does not say which part of the plant causes this, so wash your skin after handling it.