Why Are My Sorrel Leaves Curling?

Dock aphid

The dock aphid (Aphis rumicis) is a dark green to black aphid that colonises sorrel (and its close relatives the common docks) from early spring onward. Dense colonies form on the underside of the leaves, causing them to curl inward and pucker around the feeding sites. The aphids produce sticky honeydew that coats the leaf surfaces and promotes sooty mould growth. On sorrel grown for culinary use, aphid-contaminated leaves are difficult to wash clean and are unpleasant to eat; heavy infestations on young spring leaves can effectively eliminate the harvest window until the colonies are controlled.

What to do

• Inspect sorrel leaves from early April for dock aphid colonies. Small colonies on older, mature sorrel plants can be managed by removing and destroying the worst-affected leaves: the plant will produce new clean growth from its centre.
• Apply insecticidal soap spray to significant colonies, covering the underside of affected leaves thoroughly. Repeat every 5 to 7 days. On sorrel that is being harvested for eating, use only treatments approved for edible crops and observe the appropriate pre-harvest interval.
• Natural predators including ladybirds, lacewings, and parasitic wasps provide effective control of dock aphids by late spring: populations typically crash in May and June as predator numbers build up.

Slugs

Slugs attack sorrel leaves in damp conditions, particularly in spring and autumn. They rasp irregular holes in the leaf blade, and the surrounding tissue curls around the damage as the leaf expands. Young, tender spring growth from established crowns is the most attractive to slugs. In a severe slug attack, a newly re-sprouting sorrel crown can be stripped to the ground, though established plants regenerate quickly.

What to do

• Apply nematode slug control (Phasmarhabditis hermaphrodita) around sorrel crowns in early spring as the new growth emerges, and again in autumn. This provides effective protection during the most vulnerable growth periods.
• Remove slug hiding places near the sorrel patch: debris, boards, and dense vegetation immediately adjacent to the plants provide daytime shelter for slugs.

Drought

Sorrel has deep, persistent roots and is more drought-tolerant than many garden herbs, but extended drought in summer causes the leaves to wilt and curl at the margins and may trigger the plant to die back prematurely. Drought also intensifies the tartness of the sorrel flavour as the organic acids concentrate in the leaves.

What to do

• Water sorrel during extended dry spells in summer to maintain leaf production. Established sorrel in a well-composted soil position rarely needs watering except in the most prolonged droughts.
• Allow summer die-back: sorrel often dies back or reduces leaf production in midsummer heat and drought. This is normal; the plant re-shoots vigorously in autumn when temperatures and moisture levels recover.

Bolting

Sorrel produces tall flower stems in late spring and early summer (May to June in the UK). Once a sorrel plant bolts, the leaves become smaller and the plant directs its energy into seed production. The bolting stems are not harmful to the plant but do reduce leaf production during the flowering period.

What to do

• Remove flower stems as soon as they appear, cutting them off at the base. This prolongs the leaf harvest significantly and keeps the plant producing large, useful leaves rather than small, flowering-season leaves. It also prevents prolific self-seeding, which can produce unwanted sorrel seedlings throughout the garden.

Rust

Dock rust (Uromyces rumicis) occasionally affects sorrel, producing small, orange-brown, powdery pustules on the underside of the leaves and corresponding yellow patches on the upper surface. The surrounding leaf tissue curls around the pustules. Rust is more common on common dock than on cultivated sorrel, and is rarely severe enough to cause significant problems in a well-maintained sorrel patch.

What to do

• Remove and destroy affected leaves. Improving airflow around the plant and avoiding overhead watering reduces the humid conditions in which rust thrives.
• If rust is persistent, cut the entire plant to the ground in midsummer: established sorrel crowns re-shoot within a few weeks with fresh, rust-free growth.

Frequently asked questions

Why are my sorrel leaves curling?

Sorrel leaves curl most often from aphid feeding or slug damage. The dock aphid (Aphis rumicis) is the most common aphid on sorrel, colonising the underside of leaves and causing them to curl inward around the feeding sites. Slugs attack young sorrel leaves, rasping holes in the leaf blade that cause the surrounding tissue to curl and distort as the leaf develops. Sorrel shares its pest species with its close relatives the docks (Rumex species), and the dock aphid is present in most UK gardens. Sorrel leaves also naturally curl slightly in hot, dry conditions as the plant conserves moisture.

How do you use sorrel in cooking?

Sorrel has a sharp, lemony, acidic flavour from its high oxalic acid content and is used as a herb or vegetable in cooking. Young, small leaves are eaten raw in salads, where their tartness brightens a mixed leaf salad. Larger leaves are best cooked: they turn an unappetising khaki-green colour when heated (the chlorophyll breaks down in the acidic environment) but develop a rich, lemony, spinach-like flavour excellent in soups, sauces, omelettes, and gratins. Classic sorrel soup is a French dish in which the leaves are wilted in butter, blended with stock and cream, and served hot or cold. Sorrel is very good with fish, eggs, and cream-based dishes.

Is sorrel a perennial?

Yes. Common sorrel (Rumex acetosa) and buckler-leaved sorrel (Rumex scutatus) are both hardy perennials that die back in winter and re-shoot vigorously from their persistent root systems each spring. Established sorrel crowns can produce harvestable leaves for many years with minimal attention. Sorrel is one of the easiest perennial edibles to grow in a UK garden: once established, it needs little more than occasional feeding, regular harvesting, and the removal of flower stems when they appear. It self-seeds prolifically if allowed to flower and set seed, so remove the flowering stems in spring to prevent unwanted seedlings throughout the garden.

Can I eat sorrel every day?

Sorrel is safe to eat in normal culinary quantities, but its high oxalic acid content means it should not be consumed in very large quantities daily, particularly by people with kidney stones, gout, or rheumatoid arthritis, as oxalic acid can contribute to calcium oxalate crystal formation. The same caution applies to other high-oxalate foods including spinach, rhubarb, and beetroot leaves. In the context of a varied diet, sorrel used as a flavouring herb or occasional vegetable presents no health concerns for most people. Cooking reduces but does not eliminate the oxalic acid content.