PL. —Lupinus polyphyllusBotanical illustration — drop image
Lupinus polyphyllus

Lupin

SpringSummer
3a7bHardiness zone
Peak bloom windowZone 6b · frost-offset weeks
Winter
Not in bloom
Spring
Peak bloom
Summer
Not in bloom
Fall
Not in bloom
Peak bloom
In bloom
Background

Lupins are among the most spectacular spring flowers in the cutting garden — densely packed spikes of pea-flowers in a range from white and cream through every shade of pink, purple, and blue. They are a legume: the roots fix nitrogen, so they leave the soil better than they found it. They are also particular: they resent being transplanted, dislike summer heat, and grow on their own timetable.

Direct sow in autumn or very early spring — the seeds benefit from a period of cold and moisture before they'll germinate willingly. Once established, they are perennial in Zone 4–7 but often short-lived, typically at their best in years two and three. The Hudson Valley's cool springs suit them well; the key is getting them in the ground early and letting them run before the heat arrives.

They reseed readily and with vigor - consider yourself warned.

Care guide
SunFull sun to partial shade; dislikes hot afternoon sun
WaterRegular; prefers cool, moist conditions — struggles in dry summer heat
SoilWell-draining, slightly acidic (pH 6.0–6.5); as a legume it fixes its own nitrogen
Spacing18–24 inches
Height2–4 feet
Zone3a – 7b
Direct sowFrost hardy
Seasonal tasks
winter
sowDirect sow outdoors in earliest spring — they want the cold to germinate
spring
watchDo not transplant — taproots resent disturbance; mark where they are sown
watchCheck new growth for aphids — they cluster on flower buds
summer
cutCut spikes as the lower third of flowers opens; condition in cool water overnight
cutDeadhead spent spikes immediately to encourage a second, smaller flush
fall
sowDirect sow in autumn or nick and cold-stratify seeds 4 weeks before outdoor sowing
watchLeave a few spikes to set seed; collect when pods rattle
Common problems

Powdery mildew

Symptoms

White or grey powdery coating on leaves — usually starting on older growth in humid conditions or when nights cool.

Treatment

Improve air circulation by thinning plants. Apply neem oil or potassium bicarbonate spray at first sign. Avoid overhead watering.

Aphids

Symptoms

Clusters of small soft insects on new growth and flower buds.

Treatment

Knock off with a strong jet of water. Ladybirds and lacewings are natural predators. Insecticidal soap as last resort.