Germination temperature
Cool: 10-15 °C (50-59 °F); up to 18 °C (64 °F).
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Garden lupins produce tall spikes in almost every colour in early summer. Nick and soak the hard seed, sow it in deep individual pots in cool conditions and plant out into sunny, well-drained, not too rich soil.
Cool: 10-15 °C (50-59 °F); up to 18 °C (64 °F).
About 0.5 cm (1/4 in).
About 10-14 days for treated seed.
Seed is covered; plants need full sun.
Nick the seed coat, then soak for 24 hours.
Sow in individual deep pots; plant out without disturbing the taproot.
Lupin seed has a tough coat that keeps water out. Untreated seed can sit in the compost for weeks. Wear gloves: the seed is poisonous.
Recommended. Nick the seed coat with a sharp knife or rub it on sandpaper until the pale inside just shows, away from the seed scar.
Not needed. Lupins germinate without cold treatment.
Soak nicked seed in water for 24 hours before sowing; the RHS seed scheme also uses hot water for 1-3 days for unnicked seed. Sow seeds that have swelled; nick and re-soak any that stay hard.
Cool: 10-15 °C (50-59 °F) is ideal, and seed germinates up to about 18 °C (64 °F). In temperate gardens sow in early to mid spring. In warm climates, including the Indian plains, sow in the cool season after the monsoon so plants grow through winter.
Cover the seed with about 0.5 cm (1/4 in) of compost.
Free-draining seed or multipurpose compost in deep pots at least 9 cm (3.5 in) across. Lupins dislike rich, heavily manured mixes.
Keep the compost evenly moist but never soggy; soaked seed rots in wet, airless compost.
No light is needed until seedlings appear; then give them full light so they stay sturdy.
About 10-14 days for nicked and soaked seed. Untreated or older seed can take much longer, up to about 90 days.
Sow one or two seeds per deep pot and keep the stronger seedling. Plant out in spring or early summer, at the same depth as in the pot, before the taproot coils at the bottom.
Choose full sun and well-drained, neutral to slightly acid soil of modest fertility. Shade gives few flowers, and wet heavy soil rots the crown in winter.
Water regularly through the first summer and protect young shoots from slugs and snails. Most plants flower well from their second year.
Cause: the hard seed coat was not treated, or the pots were too warm. Fix: nick and soak the seed and keep pots at 10-15 °C (50-59 °F).
Cause: slugs and snails, especially on new spring growth. Fix: protect plants early in the season and check them after rain.
Cause: lupin aphid. Fix: check stems and flower spikes from spring, wash off small colonies and remove badly infested spikes.
Cause: lupin anthracnose. Fix: remove and dispose of affected shoots promptly and avoid crowding.
Cause: shade, rich soil or a pot-bound plant. Fix: grow in full sun, stop nitrogen feeding and, if needed, use a potassium-rich feed.
Russell-type border lupins reach 90-120 cm (3-4 ft) and may need staking; dwarf strains of 38-45 cm (15-18 in) suit windy spots and containers.
Cut faded spikes back to the base. This encourages further flowering and stops plants putting energy into seed.
In the ground lupins rarely need feeding. If flowering is poor, use a potassium-rich fertilizer; container plants need it through the growing season.
Most border lupins are hardy perennials where winters are cold and summers mild. In hot climates they rarely survive the summer, so treat them as cool-season plants and sow fresh each year.
Nick and soak the seed, sow it in deep pots and enjoy tall flower spikes from the second year.
Yes. Nick the hard seed coat and soak the seed for 24 hours; without it many seeds stay hard and germinate slowly or not at all.
Only while young. Lupins grow a deep taproot, so sow them in individual deep pots and plant out before the roots fill the pot. Mature plants rarely survive moving or division.
Yes. All parts of garden lupins are poisonous, and eating the seeds can cause severe discomfort. Wear gloves when sowing and keep seed away from children and pets.