How to Grow Plantain in Australia

Plantain (Plantago lanceolata, family Plantaginaceae), also called ribwort plantain, is a low perennial rosette for the herb garden. It is grown for its ribbed, lance-shaped leaves and the short brown flower spikes it holds up on wiry stalks. The store sells plantain seeds of this species, which has nothing to do with the cooking banana also called plantain (Musa). It thrives in lean soil almost anywhere in Australia. That is also the catch: it is a naturalised lawn and roadside weed, and the common mistake is letting it set seed.

Three mistakes that matter

1. Letting the spikes ripen. Every flower on a spike ripens small brown seed that drops and self-sows into lawns and beds. Cut spikes once they fade, as Trimming Flower Spikes explains.
2. Burying the seed. Plantain seed is tiny and comes up at or near the surface, where light reaches it. Press it onto damp mix or cover it with no more than 2 mm, as Germinating the seed describes.
3. Crowding and shading it. Plantain competes poorly for light, and vigorous grasses or taller plants smother young rosettes. Give each plant 20 to 30 cm of open, sunny ground, and weed around seedlings until they fill out.

When to plant

Seed starts to germinate once the soil reaches about 10°C, and trays held at 15 to 22°C usually show seedlings in 10 to 21 days. That puts the main windows in autumn and spring in most zones, and in the cooler dry season in the tropics. One sowing is enough, because each plant is a perennial that regrows from its crown.

In frosty districts, sow early in autumn so rosettes settle before the hard frosts, or start spring trays indoors. In hot inland summers, hold off until autumn, because seed on the surface dries out fast.

Site, soil and setup

Ribwort comes from the meadows, pastures and roadsides of Europe, northern Africa and western and central Asia.

Container growing

A pot is the tidiest way to grow plantain, because dropped seed lands on paving rather than in the lawn. Give each plant a pot of at least 10 L, 25 cm across and as deep, filled with a premium potting mix.

• Watering: water when the top few centimetres of mix are dry, and empty the saucer after rain.
• Feeding: fish and seaweed blend at half strength, about 12 mL per 9 L, fortnightly in spring and autumn, only if leaves pale.
• Position: full sun or light afternoon shade, away from lawn edges.
• Renewal: replace a tired plant with a fresh seedling once roots fill the pot.

Germinating the seed

Plantain seed needs no treatment: most fresh seed germinates when it is moist, mild and in the light. Dormancy varies between seed lots, and cold winter weather lifts it, which is why a winter outdoors works. The Seed Information Database, which carries the Royal Botanic Gardens, Kew, data, lists many untreated collections at 50 to 100 per cent. Several reached 100 per cent within a week at 15 to 25°C.

Light helps but is not essential. In a Dutch study, ribwort still germinated in darkness, unlike broadleaf plantain, which needs light. A study of two wild Mediterranean populations found 27 to 85 per cent, varying with temperature and seed source. Sow three seeds for each plant you want.

The seed is 2.6 to 2.8 mm long, and its coat turns into a sticky gel when wet. Sow it dry, mixed with a pinch of dry sand, so it spreads evenly.

No source names a chemical treatment for home use. Seed banks sometimes add gibberellic acid in tests, but untreated seed gave much the same results. For seed treatments in general, see soaking, scarification and cold stratification.

When nothing comes up

• Buried too deep. Sow again on the surface, pressed in, in bright light.
• Dried out. Cover the tray with clear plastic or glass until the first leaves show.
• Too cold. Little happens below about 10°C. Keep trays at 15 to 22°C.
• Seed stuck in clumps. Wet seed glues together in its gel, so sow it dry with sand.
• Given up too soon. Some batches trickle up over six weeks, so keep the tray moist that long before sowing again.

Sowing Seeds

Start plantain in trays for evenly spaced plants, or scatter it where it is to grow. Both begin from untreated seed on the surface, as Germinating the seed explains.

Starting in trays

• Fill a punnet or cell tray with fresh seed raising mix, firm it lightly and water it well.
• Press three seeds into each cell and cover them with no more than 2 mm of fine mix.
• Keep the tray just moist, in bright, indirect light at the warmth given in When to plant.
• Thin each cell to the strongest seedling once the first ribbed leaves show, snipping the rest.
• Plant out about eight weeks after sowing.

Sowing direct

Rake the bed fine and level, water it, then scatter the seed and sand thinly and press it in with the back of a rake. Mist daily until seedlings show, then thin them in stages to 20 to 30 cm apart. For more on handling small seed, see how to sow tiny seeds.

Planting out

• Plant out seedlings with four to six true leaves.
• Harden off first (stand the pots outdoors a little longer each day, so they adjust to sun and wind).
• Plant at the same depth as in the pot, keeping the crown level with the soil.
• Water in with seaweed solution at half strength, 15 mL per 9 L.
• Keep the soil moist until new leaves show, then water only in dry spells.

More on the move from pot to garden is in hardening off seedlings before planting out.

Care by growth stage

Light and room decide how well plantain grows, not feeding. It draws what it needs from poor soil, and graziers value it on low-fertility ground for exactly that reason.

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

Trimming Flower Spikes

Spikes keep coming from late winter into autumn, and each flower on them ripens two small seeds. Trimming them is the one regular job: it stops self-sowing, cuts down pollen and keeps the plant in leaf.

• Cut each stalk at its base once the ring of white stamens fades, before the spike turns brown.
• Check plants weekly through the flowering months.
• Drop cut spikes into a bag, not onto the ground, so ripe seed does not fall.
• Pull off yellowed and tough outer leaves to make room for young ones.
• For seed, bag one or two spikes on a potted plant and cut them as they brown.
• Dig out self-sown seedlings while small, taking the whole taproot, because the crown regrows.

More on keeping self-sown seedlings in check is in organic weed control.

Companion planting

Choose neighbours that stay low or share its liking for lean, sunny ground, and keep it clear of anything that will shade it.

Grows well with

• Clovers, the usual pasture partner, kept trimmed so vigorous growth does not shade the rosettes.
• Chicory, another deep-rooted perennial herb that tolerates drought and poor soil.
• Dandelion, a low rosette herb for the same sunny, lean corner.

Keep apart

• Vigorous grasses and tall, leafy crops, which shade young rosettes out.
• Lawns and vegie beds you want weed free, where dropped seed comes up as weeds.

Harvesting Leaves

Pick young leaves once a rosette has eight or more leaves, and keep picking from established plants while they grow.

• Choose the soft, upright inner leaves.
• Snap or cut them off at the base, close to the crown.
• Leave at least half the rosette so the plant keeps growing.
• Skip older outer leaves, which turn coarse and bitter.
• For drying, spread leaves in a single layer somewhere airy, warm and shaded.
• Discard any that turn dark brown or black as they dry.

Plantain leaves dry slowly, and slow drying turns them dark brown. Spread them thinly, or use a dehydrator at 40 to 50°C, and store crisp leaves in a labelled, airtight jar in a cool, dark cupboard.

Ribwort is an edible weed whose young leaves are eaten, and an early English gardening book listed its broadleaf relative among the salad herbs. Eat only leaves you have identified with certainty, picked from unsprayed ground.

Traditional use and history

Ribwort has followed farming wherever it went. Pollen analysts read its pollen as a sign of early farmers and their grazing animals. At a Neolithic lake village at Chalain, in eastern France, its pollen curve shifts through settlements dated to about 3000 to 2600 BC.

Broadleaf plantain (Plantago major) travelled with English settlers. In North America and New Zealand, Indigenous peoples called it Englishman's foot or white man's foot, because it sprang up wherever the English took land. Longfellow refers to the name in Hiawatha.

The mucilage on the seed was once used in France to stiffen muslin. The store's listing gives several of these names, and some belong to broadleaf plantain or to the Chinese species rather than to ribwort. Graziers in New South Wales and Victoria still sow bred ribwort varieties as a pasture herb.

Safety

Happy Valley Seeds sells plantain as seed for growing. Apart from the kitchen note in Harvesting Leaves, nothing here is advice to eat or take any part of the plant. Anyone thinking of using a plant should first seek advice from a qualified health practitioner.

The United States Food and Drug Administration once warned that foxglove leaf (Digitalis lanata) may have been sold in bulk as broadleaf plantain leaf. The warning followed a woman's hospital admission with heart problems. For any suspected poisoning, call the Poisons Information Centre on 13 11 26. In an emergency, call triple zero (000).

Common problems

No seedlings. Usually seed buried too deep, allowed to dry out or kept too cold; see Germinating the seed and its list, When nothing comes up.

Tall, pale, floppy seedlings. Too little light on a windowsill stretches them, so move trays to brighter light and turn them daily. Read more

Rosettes that fade among other plants. Shade and competition from grass or taller neighbours starve plantain of light; see Three mistakes that matter.

Seedlings everywhere. Spikes were left to ripen and drop seed; see Trimming Flower Spikes.

Tough, stringy leaves. Older outer leaves and plants in full flower turn coarse, so pick young inner leaves and keep cutting spikes.

Leaves that blacken as they dry. Slow drying lets them darken; see Harvesting Leaves.

Pests and diseases

The NSW pasture notes record few problems on plantain, and damp, crowded conditions favour most of them.

Common garden snail (Cornu aspersum) and grey field slug (Deroceras reticulatum). Both graze seedlings and young leaves at night in damp weather. Hand-pick them after dark, or scatter an iron-based snail bait thinly as the label directs. Read more

Damping off (Pythium species and Rhizoctonia solani). Seedlings rot at soil level and collapse, most often in wet, crowded trays. Use fresh seed raising mix and clean trays, water sparingly and thin seedlings for air flow. Read more

Ascochyta leaf spot (Ascochyta species). This leaf spot has been noted on plantain in NSW pastures. Pick off spotted leaves, water the soil rather than the foliage, and keep plants spaced for air flow.

Rhizoctonia root rot (Rhizoctonia species). It has been noted in older plantain stands, where plants decline. Keep the soil free-draining and replace tired clumps with fresh seedlings.

Meadow argus (Junonia villida). This native butterfly's caterpillars feed on ribwort and shelter under its leaves by day, and around Adelaide it is their preferred host. Leave them be: a few chewed leaves are a fair trade for the butterflies.

Prevention first

• Keep seed trays clear of rain and hose splash, which spread damping off.
• Water the soil, not the leaves, and let established plants dry out between waterings.
• Clear boards, leaf litter and loose pots from around seedlings, where snails shelter.
• Replace old, declining clumps with young plants every few years.

Tips

1. Learn the two common plantains apart. Ribwort has long, narrow leaves with ribs running their length; broadleaf plantain has smooth oval blades on long stalks.
2. Label the plant with its botanical name: plantain also names broadleaf plantain, a cooking banana and the hosta sold as plantain lily.
3. Save seed from one bagged spike. It keeps well: in one test, 94 per cent still germinated after five years at room temperature.