Sorrel (Rumex acetosa) is a hardy perennial leafy green in the buckwheat family, more closely related to dock and rhubarb than to the lettuces and spinach it's often grown alongside. It has grown wild across Europe and temperate Asia for centuries, prized for a sharp, lemony tang that comes from oxalic acid, the same compound that gives rhubarb leaves their bite. In Kentucky gardens it behaves as a true perennial, dying back in hard winters and returning reliably from the same crown each spring. Sorrel is one of the easiest leafy greens to keep going once established, needing little beyond a reasonably fertile bed and a trim whenever it tries to flower, which makes it a forgiving choice for a gardener who wants fresh greens without replanting every year.
Sowing and planting
Sorrel grows readily from seed sown direct in the garden, or it can be started indoors for an earlier crop. In zone 6b, direct sow as soon as the soil can be worked in early spring, typically March into early April; seed germinates in cool soil and the young plants tolerate a late frost once up. Sow seed shallowly, about 1/4 inch (6 mm) deep, in a bed with full sun to part shade and soil that holds moisture without staying waterlogged. Thin seedlings to 12 inches (30 cm) apart once they carry a couple of true leaves, since sorrel forms a spreading clump over time and crowded plants bolt sooner than plants with room to grow. A second sowing in late summer, around August, gives a fresh fall crop and takes advantage of the cooler weather sorrel prefers. Established plants can also be propagated by division in early spring or fall, lifting the crown and splitting it into sections that each carry roots and growing points. Sorrel also grows well in a large container, which is a useful option for a gardener who wants to move the plant into shade once summer heat sets in; use a pot at least 12 inches (30 cm) across and keep the soil from drying out, since containers dry faster than garden beds.
Growing on
Keep the soil evenly moist; sorrel's broad, thin leaves wilt quickly in dry conditions, and dry soil pushes the plant to bolt (send up a flower stalk) earlier than it otherwise would. A couple inches of mulch around the crowns helps hold moisture and keeps soil temperatures down through summer. Sorrel needs only light feeding: a yearly topdressing of compost is usually enough, since rich soil mostly produces larger leaves rather than better flavor. The plant's biggest challenge in a Kentucky summer is heat, which triggers flowering and turns the leaves tough and increasingly bitter; siting the bed in part shade, especially afternoon shade, slows this down. As soon as a flower stalk appears, cut it back at the base; this single step does more than anything else to keep the leaves tender and the plant productive through summer. Established clumps spread by short rhizomes and benefit from division every three to four years to keep them vigorous. Sorrel isn't fussy about soil pH, tolerating anything from slightly acidic to neutral, and it has few serious weed problems once the clump fills in, since the dense foliage shades out most seedlings on its own.
Harvesting
Sorrel is a cut-and-come-again crop rather than one with a single harvest date. Leaves are usually ready for a first light cutting about 50 to 60 days from seed, once the plant has a decent rosette of growth; established perennial plants can be picked as soon as new leaves emerge in spring. Harvest the outer, older leaves first, snapping or cutting them near the base and leaving the inner crown to keep producing; young, smaller leaves are the most tender and least sour, while older leaves turn tougher and more acidic. Spring and fall are the two best harvest windows in Kentucky, when cool temperatures keep growth tender; expect the plant to slow down and toughen in the heat of midsummer, especially if flower stalks aren't kept cut back. Because of its oxalic acid content, sorrel is best used in the kind of modest quantities typical of a salad green or soup ingredient; it's fine in ordinary culinary amounts, but it isn't a vegetable to eat by the bowlful, which is worth keeping in mind especially for anyone prone to kidney stones.
Problems and pests
Leaves turn tough and sharply bitter by midsummer
This is bolting, not a pest or disease: long days and summer heat push sorrel to flower, and the plant's energy shifts away from tender leaf growth. Cut flower stalks out as soon as they appear, keep the bed consistently watered, and consider a spot with afternoon shade to slow the plant down through the hottest weeks.
Ragged holes chewed through the leaves overnight
Slugs and snails favor sorrel's soft, moisture-retaining leaves, especially in a damp spring bed. Handpick them in the evening or early morning, set out shallow traps, and keep mulch from sitting directly against the crown, where slugs like to shelter during the day.
Orange or rust-colored pustules on the leaf undersides
Rust fungus occasionally shows up on sorrel in humid weather, appearing as small raised spots on the underside of leaves with matching yellow blotches above. Strip and discard affected leaves, water at soil level instead of overhead, and give plants enough spacing for air to move freely through the bed.
Pale, winding tunnels through the leaf tissue
Leaf miner larvae tunnel between the leaf surfaces, leaving trails that are mostly cosmetic but make leaves unappealing to eat fresh. Pick off and destroy mined leaves as you spot them, and a floating row cover over young plants keeps the adult flies from laying eggs in the first place.
Clusters of small insects on new growth
Aphids sometimes gather on young sorrel leaves and flower stalks, especially in spring. A strong jet of water knocks most colonies off, and insecticidal soap handles anything that persists; aphids rarely do lasting damage to an established plant.
Varieties worth growing
- Common/Garden sorrel – The standard Rumex acetosa, grown from seed and the variety most seed catalogs sell under the plain name "sorrel," with the classic sharp, lemony bite.
- French sorrel (Rumex scutatus) – A lower-growing relative with smaller, shield-shaped leaves and a milder, less acidic flavor, that also tends to hold up a little better in heat.
- Red-veined sorrel (Rumex sanguineus) – Grown as much for its bright red leaf veining as for the kitchen, with a flavor similar to common sorrel, often used young as a salad garnish.
- Profusion – A sterile cultivar that rarely if ever flowers, which means it skips the bolting-related bitterness of seed-grown sorrel and keeps producing tender leaves longer into summer.
- Large Leaf/Belleville – An old, vigorous strain with broad leaves and good productivity, well suited to a gardener who wants a bigger harvest from fewer plants.