How to Grow Sorrel in Australia

Garden sorrel (Rumex acetosa) is a hardy perennial leaf herb in the dock family, Polygonaceae. It is grown for sharp, lemony leaves that lift salads, soups, egg dishes and sauces for fish. Red-veined sorrel (Rumex sanguineus) is grown the same way for its green leaves traced with deep red. Two or three plants usually keep a household supplied for years, and the mistake to avoid is letting them flower.

Three mistakes that matter

1. Letting it flower. Once a flower stem rises, the plant puts its effort into seed, fresh leaves slow down and seedlings later pop up across the bed. Snip flower stems as soon as they show, as Cutting Back describes.
2. Sowing into heat or letting the soil dry. Hot weather and dry soil push sorrel to bolt (run up to flower early), and the leaves turn tough and unpleasant. Sow in the windows in When to plant, and keep the soil evenly moist.
3. Picking too little. Leaves left on the plant grow large, tough and bitter, and the clump makes fewer new ones. Pick often, as Harvesting Leaves describes, so young, tender growth replaces them.

When to plant

Sorrel seed sprouts in one to two weeks in soil between about 15 and 22°C. That puts the main sowing windows in the mild weeks of autumn, around Anzac Day, and again from late winter into spring. One sowing gives plants for several years, so sow again only to add plants or replace tired clumps.

In frosty districts, raise late autumn sowings under cover and plant them out in spring. Young plants are more tender to cold than established clumps.

Site, soil and setup

Sorrel stays in one spot for years, so rotation does not apply. Give it a permanent place at the edge of the vegie patch or in the herb bed. Choose it with care, because garden sorrel can become invasive and its deep taproot makes an old clump hard to remove. A path or firm edging helps hold it in place.

Container growing

A pot stops sorrel spreading through a bed and lets you move it out of the heat. Use one at least 30 cm wide and 20 cm deep, about 13 L, and deeper if you can, because both sorrels form a taproot. Fill it with quality potting mix. Red-veined sorrel is the compact choice; garden sorrel needs the larger pot.

• Water: check the mix often in warm weather and keep it evenly moist, because pots dry out fast and dry sorrel bolts.
• Feed: fish emulsion at half strength, monthly from spring to autumn.
• Position: morning sun, moved into shade during hot, sunny spells.
• Winter: stand the pot in a sheltered spot out of heavy rain so the mix never becomes waterlogged.

Sowing Seeds

Sorrel grows readily from seed sown straight into the bed or in punnets for planting out.

Sowing direct

• Rake the soil fine and sow thinly, 5 to 10 mm deep, in short rows.
• Keep the surface moist until seedlings appear, usually in 7 to 14 days.
• Thin seedlings to 20 to 30 cm apart once they are big enough to handle.

Due to quarantine restrictions and our shipping policy, we cannot send sorrel seed to Western Australia. The two sorrels differ mainly in size and leaf, which changes where they fit.

Starting in punnets

• Sow 5 to 10 mm deep in cells or small pots of seed raising mix, in a warm, bright spot.
• Move each seedling into its own small pot once it has several leaves.
• Plant out when seedlings are 5 to 10 cm tall with a couple of sets of true leaves, disturbing the roots as little as possible.
• First harden off (move seedlings outdoors for longer each day over about a week), as hardening off seedlings explains.
• Plant at the depth they grew in the pot, 20 to 30 cm apart, and water in well.

Care by growth stage

Steady moisture decides how sorrel grows.

If growth stalls in poor soil, a light dose of all-purpose controlled release granular (NPK around 14-5-10) scratched in each spring can help.

Cutting Back

Regular cutting keeps sorrel in leaf, and a tired, coarse clump responds to a hard cut with a flush of tender growth.

• Flower stems: snip each one at its base as soon as it shows.
• Seed heads: if any flowers slip through, cut them before the seed ripens and blows about.
• Old leaves: pull off yellowing, tough or bitter leaves to make room for new ones.
• Tired clumps: cut all the leaves back to a few centimetres, water, then feed once as Care by growth stage shows.
• Dividing: lift and split clumps every four or five years in spring or autumn, as dividing perennials explains.
• After winter: clear away dead leaves once new growth starts in spring.

Red-veined sorrel may be an environmental weed in some districts, so check with your local council before planting it near bushland.

Companion planting

Sorrel suits a permanent bed with other long-lived edibles that like the same rich, moist soil.

Grows well with

• Rhubarb, another long-lived perennial for a rich bed, whose big dark leaves contrast with bright green sorrel.
• Rocket and mizuna, cut-and-come-again greens picked through the same cool months.

Keep apart

• Mint, which spreads by creeping roots into neighbouring clumps.
• Lavender and thyme, which need lean, free-draining soil that sorrel finds too dry.

Harvesting Leaves

Start picking when leaves are 8 to 10 cm long, usually 8 to 12 weeks after sowing, and keep picking from then on.

• Pinch or pull each leaf off at the base of the plant, and discard the tough stalk.
• Take young leaves for salads and larger ones for cooking.
• Pick regularly, even when the kitchen does not need them, to keep new leaves coming.
• Wash the leaves well before use.

Sorrel is best used fresh. Leaves keep in the fridge for a couple of days, or can be blanched and frozen for cooking.

The leaves wilt to a puree in moments, which suits soups, sauces for fish and omelettes. Avoid aluminium pans, because the acid in the leaves reacts with the metal and gives a metallic taste.

Oxalic acid gives sorrel its sour bite. Like spinach and rhubarb, sorrel is a high-oxalate food that can harm people and pets eaten in large amounts, so use it in moderation. Anyone prone to kidney stones or gout may wish to ask their doctor before eating it often.

Common problems

No seedlings. Seed sown too deep, or in soil that dried out or stayed cold, may not come up. Resow in the windows in When to plant. Read more

Plants vanish in winter. In frosty gardens sorrel dies back to the crown and resprouts in spring, so leave the spot undisturbed.

Scorched, yellowing leaves in summer. Hot afternoon sun on dry soil burns the leaves; give shade, mulch and water, then cut the damaged leaves off.

Pests and diseases

Settled clumps are usually healthy, so most damage falls on seedlings and soft new leaves.

Garden snail (Cornu aspersum) and slugs. They chew holes in leaves and can strip seedlings overnight, leaving silvery slime trails, most often after evening rain. Hunt them by torchlight, and set beer traps or copper tape around wooden or plastic pots and beds, not corrugated iron, which it corrodes. Read more

Aphids (family Aphididae). These small, soft-bodied sap suckers cluster on tender new growth and can stunt it. Ladybirds, lacewings and parasitic wasps usually keep them in check, so hose them off or use insecticidal soap only on heavy colonies. Choose a soap labelled for the crop, and keep to its withholding period before picking. Read more

Damping off (Pythium species and Rhizoctonia solani). Seedlings rot at soil level and collapse, most often in wet mix during cool weather. Read more

Prevention first

• Sow into fresh seed raising mix in clean punnets, and avoid overwatering.
• Start seedlings under cover where snails are bad, and plant them out once they are sturdy.
• Check under leaves and around rocks and edges for sheltering snails.
• Skip broad insecticide sprays, which kill the predators that eat aphids.

Tips

1. Sow red-veined sorrel among autumn flowers, where it earns its place as an ornamental you can also eat.
2. Shred a few young leaves into an avocado salad or sandwich for a lemony lift.
3. Do not mistake sheep sorrel (Rumex acetosella), a small, creeping weed of pastures in cooler, wetter districts, for the garden herb. Its spreading underground stems make it hard to pull out.