Lupin Harwtwegii can be grown from seeds, cuttings or divisions. If growing from seed, germination is greatly increased by a 7-day cold treatment . Place seeds and slightly damp paper towels in a Ziploc bag and store in the refrigerator. Another method would be to soak them in warm water for a 24-hour period. Treated seeds can be directly sown into a seedbed in spring or summer until August 1st. The best time to plant untreated lupine seeds outdoors is between September-November.
Plants grown from seed will bloom their first year. Pinch off spent flowers to prolong the blooming period. Apply an organic fertilizer once per month to promote healthy plants and large blooms.
To grow from cuttings, take a stem down to the trunk, including a bit of its “footprint” connection to the trunk. Set in moist, very well-drained, gritty sand or other propagation medium. Keep covered during the propagation period except for several minutes each day to air and and allow the plant to adjust.
Start cuttings in larger pots that can be transplanted into the outdoors, pot and all, so as not to disturb the roots.
Do NOT transplant as the long tap root is delicate, and if damaged, the plant will fail.