How to Grow Purslane in Australia

Purslane (Portulaca oleracea) is a succulent leafy green from the family Portulacaceae, grown for crunchy, tangy leaves and stems eaten raw or cooked. It grows wild over much of Australia, where Aboriginal people ate the leaves and ground the seed for baking. It keeps cropping through summer heat that sends lettuce to seed, and the one thing most gardeners get wrong is sowing it into cold soil.

Three mistakes that matter

1. Sowing into cold soil. Purslane is a warm-season plant, and seed sown into cold spring soil often fails to come up at all. Wait until the soil holds at least 18°C and frosts are over, or start seed indoors in trays.
2. Burying the seed. The seed is about 1 mm across and germinates in response to light, so a normal sowing depth leaves it in the dark. Press it onto the surface and cover it with no more than 3 mm of fine mix.
3. Letting plants set seed. Purslane can flower within weeks of coming up, and each plant sheds thousands of seeds that stay alive in the soil for years. Pick shoot tips often and pinch out flower buds, so the crop stays leafy and the bed stays yours.

When to plant

Soil temperature decides it. Seed germinates at 18°C to 32°C, so sow once the soil holds at least 18°C and the last frost has passed. For a steady supply of tender tips, sow a small batch every two to three weeks through the window.

In cool districts, raise early seed indoors and plant out around Melbourne Cup weekend, once frosts are over. Late sowings slow as autumn nights cool, and the first frost ends the crop.

Site, soil and setup

Wild purslane in a bed usually marks fertile soil, so that bed suits a sown crop too.

Purslane belongs to none of the common vegetable families, but it hosts root-knot nematode. Do not sow it straight after a crop that nematodes have troubled.

Container growing

A pot suits purslane well and stops it seeding through the garden. Use a pot of at least 10 L and 25 cm across, filled with premium potting mix. Both forms grow in pots, and the compact golden purslane suits smaller ones best.

• Water: check pots daily in hot weather and water when the mix is dry a few centimetres down; see watering pots in summer.
• Feed: fish and seaweed blend at 25 mL per 9 L, fortnightly once picking starts.
• Position: full sun for at least 6 hours a day, such as a deck or a spot near the kitchen door.

Sowing Seeds

Sow purslane where it is to grow, or start it in trays while the soil outside is still cool.

Choosing a variety

Both reach picking size in about 50 to 60 days and are grown the same way. Moss rose (Portulaca grandiflora) is an ornamental cousin grown for its flowers. Miner's lettuce (Claytonia perfoliata), sometimes sold as winter purslane, is a different plant altogether.

Sowing direct

• Rake the bed to a fine surface and water it the day before.
• Mix the seed with dry sand so it spreads evenly, then scatter it thinly.
• Press the seed in and cover it with no more than 3 mm of fine soil or seed-raising mix.
• Keep the surface damp with a fine spray; seedlings usually emerge in 7 to 14 days.
• Thin the seedlings as they grow; see Thinning.

Starting in trays

Trays give an earlier start in cool districts and keep tiny seedlings away from snails.

• Fill cells with seed-raising mix, sow three or four seeds per cell and dust them with 3 mm of mix.
• Keep the trays warm, between 18°C and 32°C, and the mix just damp.
• Thin to the two strongest seedlings in each cell.
• Harden them off (gradually getting seedlings used to outdoor sun and wind) over about a week; see hardening off seedlings.
• Plant out after the last frost, at 5 to 10 cm tall with true leaves. Set them 20 to 30 cm apart and disturb the roots as little as possible.

Care by growth stage

Steady moisture decides leaf quality: purslane survives drought, but plants kept dry give small, tough leaves. Feed lightly, because fertile soil and a little nitrogen are all it needs. Weeks count from sowing.

If growth stalls in poor soil, a light dose of all-purpose controlled release granular (NPK around 14-5-10) scratched into the soil can help. More is not better, as heavy nitrogen feeding can encourage mealybug outbreaks.

Thinning

Thinning gives each plant room to spread, and regular pinching keeps it branching and leafy rather than flowering.

• Thin direct-sown seedlings to about 10 cm apart once they have true leaves, and eat the thinnings.
• Thin again to 20 to 30 cm apart as the plants begin to touch.
• Pinch out the growing tips once plants have several pairs of leaves, so they branch.
• Pinch out flower buds as soon as they show.
• Cut tired plants back to about 5 cm above the soil to push out fresh stems.
• Pull self-sown seedlings where they are not wanted, before they flower.

Companion planting

Purslane's low mat shades the soil, so it partners best with tall summer crops and worst with slow, low ones it can smother.

Grows well with

• Sweet corn, whose shallow roots can follow purslane's deeper roots, while the mat keeps the soil cool and moist.
• Dwarf beans, which grow up through a purslane ground cover that holds moisture around them.

Keep apart

• Onions and beetroot, slow, low crops that purslane competes with for light, water and space.
• Tomatoes in a bed with root-knot nematode, because purslane hosts the nematode and carries it between crops.

Harvesting Leaves

Start picking when the stems are long enough to snip, usually 50 to 60 days from sowing, and keep picking before the flower buds open.

• Snip stems to within about 5 cm of the base; new shoots are usually ready in about three weeks.
• Take young, tender tips for salads; older, thicker stems are better cooked.
• Pick in the early morning for the tangiest flavour, or late in the day for a milder one.
• Eat the flower buds too, since the leaves, stems and buds are all edible.

Refrigerate purslane straight after picking to keep it crisp, in a perforated bag, and eat it soon. Use it raw in salads, stir it through yoghurt, or cook it like spinach; its slightly slippery texture thickens soups and stews. Like spinach, it is high in oxalic acid, so eat it in moderate amounts, and people prone to kidney stones may wish to limit it.

Common problems

Seed not coming up. Cold soil or deep sowing is the usual cause, as described in Three mistakes. Read more

Early flowering. Hungry plants tend to flower sooner, so pinch out the buds and give a fortnightly feed of fish emulsion at half strength.

Plants collapsing in wet weather. Plants standing in soggy soil can rot and die, so let the surface dry between waterings and raise beds that stay wet.

Purslane everywhere next summer. Seed shed in earlier seasons sprouts whenever digging brings it to the light, as described in Three mistakes. Mulch beds you want kept clear 8 to 10 cm deep. Read more

A look-alike in the patch. Before eating a self-sown plant, snap a stem. Purslane sap is clear, while spurges such as petty spurge (Euphorbia peplus) bleed milky sap and must not be eaten.

Pests and diseases

Purslane has few serious pests, so a weekly look at shoot tips and stems while you pick catches most trouble early.

Aphids (family Aphididae). Small sap-sucking insects cluster on new shoots and under leaves, leaving sticky honeydew. Hose them off or spray insecticidal soap, and let ladybirds and lacewings do the rest. Read more

Solenopsis mealybug (Phenacoccus solenopsis). Dense, white, waxy colonies form on stems and shoots, and this mealybug is recorded on wild purslane in Australia. Cut out infested stems and dab small colonies with methylated spirits on a cotton bud. Read more

Common garden snail (Cornu aspersum). Snails, and slugs with them, chew seedlings overnight, especially in damp weather. Collect them by torchlight and raise early seedlings in trays. Read more

White rust (Wilsoniana portulacae). Leaves pale and carry raised, chalky white blisters in cool, wet weather, and the spores spread in splashing water. There is no cure, so pull and bin affected plants and water the soil rather than the leaves.

Root-knot nematode (Meloidogyne species). These microscopic soil worms raise lumpy galls on the roots, and affected plants stunt, yellow or wilt. Pull infected plants with their roots, dig in compost and rotate beds. Read more

Prevention first

• Raise early seedlings in clean trays with fresh seed-raising mix.
• Water the soil in the morning, not the leaves.
• Keep plants 20 to 30 cm apart so air moves through the mat.
• Bin diseased and finished plants rather than composting them, before their seed falls.

Tips

1. Purslane roots readily from stem cuttings. Push a short piece into moist potting mix to fill a pot or share a plant with a neighbour.
2. When weeding in summer, leave a few self-sown purslane seedlings between tall crops. Wild plants are the same species, though the sown forms have larger leaves.
3. To save seed, let one plant of one variety flower in a pot and stand it on newspaper as the capsules ripen. The tiny black seed falls out on its own.