Sorrel is a perennial herb recognized for its distinctive, bright, lemony flavor, which comes from oxalic acid. Valued in European cuisine for centuries, it adds an acidic tang to various dishes. The plant’s common name covers several species, and whether it is considered a useful garden herb or an unwelcome weed depends entirely on the specific variety and its location.
Botanical Identity and Key Species Differentiation
Sorrel belongs to the genus Rumex, a group of plants within the buckwheat family (Polygonaceae) that includes docks. This genus contains approximately 200 species globally, many known for their erect growth and deep root systems. The three most common species encountered by gardeners are distinct in their growth habits and appearance.
Common or Garden Sorrel (Rumex acetosa) is the primary cultivated variety, growing up to two feet tall with large, arrowhead-shaped leaves. French Sorrel (Rumex scutatus) is smaller and preferred for its milder flavor, contained in its smaller, shield-shaped leaves. These two species are typically grown intentionally in controlled garden settings.
The third common type, Sheep Sorrel (Rumex acetosella), is frequently the source of the “weed” designation. This species is noticeably smaller than its cultivated cousins, featuring diminutive, arrow-shaped leaves. Its growth habit is the main distinguishing factor, as it spreads aggressively via a network of creeping underground stems called rhizomes.
The Context of Sorrel’s “Weed” Status
The label of “weed” is most often applied to the highly invasive Sheep Sorrel. Due to its competitive nature, it has been listed among the world’s worst weeds. Its aggressive reproduction through rhizomes allows it to form dense, spreading clonal colonies that persist for many years. These creeping root systems effectively out-compete cultivated plants for light, water, and nutrients.
A plant is classified as a weed when it grows where it is not wanted, and Sorrel’s resilience makes it a problematic invader of lawns, vegetable beds, and pastures. Many Rumex plants, including aggressive dock types, develop long, tenacious taproots. If the entire root is not removed, the plant readily sprouts new top growth from fragments left behind, making eradication difficult.
Species like Sheep Sorrel rapidly colonize disturbed or acidic, nutrient-poor soils, contributing to its reputation as a difficult weed. Even cultivated Common Sorrel (R. acetosa) can be aggressive, as its flower spikes produce numerous seeds that allow it to self-sow and spread beyond its intended location. The perception of Sorrel as a weed is rooted in the vigorous, hard-to-control growth of certain species.
Cultivation and Intentional Uses in the Garden
When grown intentionally, the desirable Sorrel species (Rumex acetosa and Rumex scutatus) are valued culinary herbs. They thrive in well-drained, loamy soil and prefer full sun to partial shade. These perennials are relatively problem-free once established.
To ensure a continuous supply of tender leaves and prevent the plants from becoming overly aggressive, cut off the flower stalks as soon as they appear. This practice directs the plant’s energy into producing leaves rather than seeds, encouraging a longer harvest period. Harvesting is best done by regularly cutting the outer, mature leaves, allowing the inner, younger leaves to continue growing.
The leaves of cultivated Sorrel impart a bright, acidic flavor to food, similar to lemon or green apples. They are frequently incorporated into spring salads or cooked into classic French Sorrel soup and sauces, especially those paired with fish or eggs. The young leaves offer the best texture and flavor, as mature leaves can become tougher and more intensely sour.
Management Strategies for Unwanted Growth
For gardeners dealing with unwanted Sorrel, particularly the rhizomatous Sheep Sorrel, control requires persistence and a targeted approach. The most effective non-chemical method is manual removal, performed with great care to extract the entire root system. Digging should be done when the soil is loose and moist, as this makes it easier to pull the deep taproots and creeping rhizomes without snapping them.
Repeated cultivation or hoeing that consistently removes the top growth can eventually deplete the energy stores in the roots, starving the plant. Mulching with thick layers of organic material can also suppress the emergence of new shoots and seedlings.
Since Sheep Sorrel favors acidic soil, amending the area with lime to increase the soil’s pH makes the environment less hospitable for the weed. For large, established infestations, chemical control may be considered, focusing on general systemic herbicides applied to actively growing plants. Products containing active ingredients like dicamba or triclopyr are suggested for perennial weed control. Any chemical application should strictly follow the product’s instructions to minimize impact on surrounding desirable vegetation.