Germination temperature
Alternating 20-30 °C (68-86 °F) gave over 90% germination; a constant 18-20 °C (64-68 °F) gave about 40%.
Herb growing guide
Broadleaf plantain is a tough, low rosette herb that thrives in sun or part shade and even on compacted ground. Its very small seed needs light and warmth that swings between day and night, so sow it on the surface and keep it moist.
Alternating 20-30 °C (68-86 °F) gave over 90% germination; a constant 18-20 °C (64-68 °F) gave about 40%.
Surface to 5 mm (0.2 in); seedlings rarely emerge from below 10 mm (0.4 in).
Not well documented; emergence is often staggered.
Needed. Few seeds germinate in darkness or under a leaf canopy.
Not needed for stored seed.
Either; direct sowing is simple, or raise in trays and transplant.
The seed is tiny, about 0.20 g per 1,000 seeds. Mix it with dry fine sand before sowing so it spreads thinly. The seed coat turns sticky and gel-like when wet, which helps it hold moisture but makes wet seed clump.
Not needed. There is no hard seed coat to break.
Not needed for purchased seed. In the wild, freshly shed seed stays dormant until the following spring; seed that has been stored over a winter is ready to sow.
Not recommended. Soaked seed becomes slimy and hard to sow evenly; sow dry seed onto a moist surface instead.
Warm days and cooler nights work best: alternating 20-30 °C (68-86 °F) raised germination above 90%, compared with about 40% at a constant 18-20 °C (64-68 °F). An outdoor tray or an unheated room gives natural day-night swings.
Sow on the surface and press in, or cover with no more than 5 mm (0.2 in) of fine mix. Emergence drops off sharply below that, and 10 mm (0.4 in) is about the limit.
Any fine, moist seed mix. Plants later grow in clay, loam or organic soils and tolerate compacted, disturbed ground.
Keep the surface constantly moist. Germination fell by up to 40% as soil dried in field observations.
Leave seed uncovered or only barely covered. In one test only 2% germinated under a leaf canopy, against 68% in diffuse light.
No reliable day count is published. In the wild seedlings emerge sporadically through the growing season, so expect some to come later than others.
Move tray-raised seedlings once they have a few true leaves, keeping the root ball intact. In beds, thin direct-sown seedlings so each rosette has room to spread.
Growth is quick: plants may flower about 90 days after germination and can set seed as early as six weeks. Pick young leaves while they are tender.
Cause: seed buried too deep or kept in the dark. Fix: sow on the surface or under no more than 5 mm (0.2 in) of mix, in good light.
Cause: a constant room temperature. Fix: give a day-night swing, ideally between about 20 and 30 °C (68-86 °F).
Cause: the tiny seed sits in the top few millimetres, which dry first. Fix: mist or bottom-water and cover trays until seedlings appear.
Cause: a single plant can produce around 14,000-20,000 seeds, which stay viable in soil for many years. Fix: cut flower spikes before they ripen unless you want seed.
Plantain grows in full sun or part shade, in clay or loam, and tolerates compacted ground and occasional wetness, so it suits path edges and spare corners.
Young leaves are the most tender; older ones are tougher. Removing flower spikes keeps the plant producing leaves.
In hot lowland climates, sow when days are warm and nights are clearly cooler, which gives the alternating temperatures the seed responds to.
Flower spikes appear from spring through summer. Cut ripe spikes into a paper bag; dry-stored seed has been reported to stay viable for up to about 10 years, so sow within a few seasons.
Grow your own patch of hardy broadleaf plantain for fresh young leaves.
Barely, if at all. The seed needs light, and the best emergence is from the top 5 mm (0.2 in); almost none emerge from below 10 mm (0.4 in).
Constant warmth is not ideal. Germination was about 40% at a steady 18-20 °C but over 90% with temperatures alternating between 20 and 30 °C.
No. Broadleaf plantain is Plantago major, a small rosette herb. The cooking banana called plantain belongs to the genus Musa.