Why Are My Artichoke Leaves Curling?

Blackfly

Black bean aphid (Aphis fabae), commonly known as blackfly, is the most significant pest of globe artichokes in UK gardens. The aphids colonise the growing tips, the stems directly beneath the developing flower buds, and the inner surfaces of the outermost bracts of the artichoke head itself. Dense colonies cause the surrounding leaves and bracts to curl inward around the feeding sites, and the sticky honeydew they produce coats the developing head and promotes sooty mould growth. Blackfly infestations on artichokes are most severe in May, June, and July, coinciding with the period when the heads are developing and of most value to harvest.

What to do

• Inspect artichoke plants weekly from May for blackfly colonies. The first colonies typically establish on the growing tips and in the leaf axils; catching them at this early stage before they spread to the developing heads is important for protecting the crop.
• Squash small colonies by hand or remove them with a strong jet of water. Apply insecticidal soap spray to larger colonies on the stems and leaves, covering all surfaces. Repeat every 5 to 7 days.
• Colonies within the bracts of developing heads are more difficult to remove without damaging the head; wash the head thoroughly before cooking if aphids have penetrated the outer bracts.
• Natural predators including ladybirds and lacewings provide effective control on artichokes later in summer once predator populations have built up: avoid broad-spectrum insecticides that would disrupt this natural control.

Drought

Globe artichokes require substantially more water than their drought-tolerant appearance suggests. Despite the silvery, drought-adapted look of the leaves, artichokes produce very large root systems and substantial above-ground growth that needs consistent moisture throughout the growing season. Drought causes the large leaves to droop and curl at the margins, and the developing heads may shrink or fail to develop to full size. The plants are particularly water-demanding in June and July when the heads are swelling.

What to do

• Water artichoke plants during dry spells from April through to harvest, giving a deep soaking every 10 to 14 days in dry conditions. Artichokes planted in well-composted soil are significantly more drought-tolerant than those in thin, sandy soils.
• Apply a generous mulch of compost or straw around the base of the plants in spring to conserve soil moisture through summer and suppress weeds that would compete for water.

Artichoke leaf spot

Several fungal pathogens cause leaf spot diseases on artichokes in the UK, producing brown, circular spots that enlarge and merge in wet conditions, causing yellowing and curling of the affected tissue. Botrytis (grey mould) is the most common, particularly on the outer bracts of the heads during wet summers and on the cut stems of previously harvested plants. It produces a characteristic grey, fuzzy mould on affected tissues. Leaf spot diseases are most prevalent after wet, overcast weather.

What to do

• Remove and destroy affected leaves and cut down any dead stem material promptly. Botrytis spreads from dead and dying tissue to adjacent healthy tissue: removing dying material is the primary control measure.
• Cut harvested stems cleanly just above a leaf joint and allow the cut surface to dry rather than leaving ragged stubs, which are more susceptible to botrytis infection.
• Ensure good airflow around the plants by spacing them at least 90 centimetres apart.

Wind damage

Globe artichokes produce very large leaves and tall flower stems that are vulnerable to wind damage in exposed gardens. Strong winds tear and shred the large leaf blades, causing them to curl and brown along the damaged edges. The tall flower stems may be snapped or bent by strong winds. Wind damage also increases water loss from the large leaf surfaces, compounding drought stress.

What to do

• Plant artichokes in a sheltered position away from prevailing winds, ideally with a hedge, wall, or fence providing some protection to the north and west.
• Support tall flower stems with a bamboo cane when the heads are developing and the stems are heaviest.

Slugs

Slugs attack young artichoke plants and new growth emerging from established crowns in spring, rasping holes in the unfurling leaves that cause them to emerge with irregular, curled edges. New growth emerging from divisions or newly planted offsets is particularly vulnerable in April and May.

What to do

• Apply nematode slug control (Phasmarhabditis hermaphrodita) around newly planted artichoke offsets and around established crowns as they begin to produce new growth in spring. This provides protection through the most vulnerable early growth period.
• Established artichoke plants with mature foliage are largely unaffected by slug damage except on the youngest emerging leaves.

Frequently asked questions

Why are my artichoke leaves curling?

Globe artichoke leaves curl most often from blackfly infestation, drought, or wind exposure. Blackfly (Aphis fabae) colonises the growing tips and the stems beneath the developing flower buds, causing the surrounding leaves to curl inward around the dense colonies. Drought causes the large, silvery-grey leaves to droop and curl at the margins: artichokes have substantial water demands during summer despite their Mediterranean appearance. Strong winds tear and batter the large leaves, causing them to curl, brown at the tips, and shred along the margins.

When do globe artichokes produce heads?

Globe artichokes raised from seed do not typically produce heads in their first year: the plant spends the first growing season establishing its root system and producing foliage. Plants raised from offsets (divisions of established crowns) often produce a small number of heads in their first summer if planted early in spring. From the second year onward, established artichoke plants produce heads from May or June through to August, with the main flush in June and July. Each plant can produce 4 to 8 heads per season from established crowns, and a well-maintained plant continues to produce for 5 to 8 years before needing division.

How do I overwinter globe artichokes in the UK?

Globe artichokes are reasonably hardy in most of the UK, tolerating temperatures down to about -5 to -8 degrees Celsius with some protection. After the last harvest in late summer or early autumn, cut the main stems back to about 30 centimetres above the ground. In mild areas (most of the UK), cover the crown with a thick layer of straw or bracken held in place with horticultural fleece or netting. In colder areas or on heavy, waterlogged soils, lift the plant in late October, divide the offsets, and store the young crowns in a cool, frost-free place over winter before replanting in spring. Waterlogging in winter is more likely to kill artichokes than cold alone.

How do you eat a globe artichoke?

A globe artichoke is cooked whole by boiling or steaming until the base of an outer leaf can be pulled free easily (typically 25 to 40 minutes, depending on size). Pull off the outer leaves one by one, dip the base of each leaf in melted butter or vinaigrette, and scrape the fleshy base off with your teeth. Discard the fibrous leaf bracts. Once all the leaves are eaten, remove the hairy choke from the centre with a spoon, and eat the tender, meaty heart underneath with more dipping sauce. Baby artichokes (harvested small before the choke develops) can be halved and roasted, fried, or eaten raw when very small.