Ornamental · Fabaceae
Lupine
Lupinus polyphyllus
Give it full sun, cool roots, and lean soil, and lupine throws up tall spires of color from late spring into summer.
Full sun
Every 3–7 days
USDA 4–8
3–4 ft · 0.9–1.2 m
Overview
Lupine gives a garden height and drama, sending up tall spires of pea-like flowers that read from across the lawn and carry the border through the first warm weeks of the year. As a member of the legume family, it feeds itself and leans on the soil only lightly, which makes it an easy anchor for a relaxed, low-fuss planting scheme. The bigleaf type behind most garden strains comes from western North America and has settled across cool, temperate country, lending it an unforced, cottage-garden ease.
Nearly every named plant you will meet descends from the Russell hybrids, a strain prized for full, tightly packed spikes in clear colors and painterly bicolors that pair beautifully with roses, hardy geraniums, and a backdrop of soft foliage. They are short-lived perennials that reward a cool-summer setting, and a sunny bed with sharp drainage turns them into the standout of the early season. Set them mid-border where their spires can rise above lower companions.
One point belongs in the plan from the outset. Every part of lupine holds quinolizidine alkaloids, densest in the seeds and pods, so it earns its place as a plant to admire rather than to bring anywhere near the kitchen. Site it for the view, keep it away from grazing animals, and let it do what it does best, which is put on a show.
Care
The short version: give lupine a full-sun bed with cool roots, moderately rich, well-drained, slightly acidic soil, and even moisture. Feed it lightly, deadhead the spent spires, and fold in fresh plants every few years.
Light
Lupine belongs in full sun, where the spires stand tallest and hold their color across the bed. It will accept partial shade, the afternoon kind especially in warmer gardens, though a shadier spot leaves you with fewer, looser flowers and a softer effect.
Water
Keep the soil evenly moist without letting it turn heavy and wet, since lupine asks for medium moisture rather than a boggy footing. A mulch in warmer gardens keeps the roots cool and the moisture even through the season. Sharp drainage counts for as much as the watering itself.
Soil
Give lupine a bed of moderately rich, well-drained loam worked through with organic matter. It leans toward the acidic and settles happiest at a pH of 5.5 to 6.5, so chalky or heavy ground tends to hold it back.
Temperature
This is a hardy plant that carries through winters down to -29°F (-34°C) but chafes at real heat much past 84°F (29°C). Cool summers keep it at its best, while hot, humid ones cut its run short.
Humidity
Average outdoor humidity suits lupine, so there is no figure to fuss over. What matters to the display is airflow, because still, damp air around a crowded planting is what invites powdery mildew onto the leaves.
Feeding
As a nitrogen-fixing legume, lupine makes much of its own and needs barely any feeding, a light low-nitrogen feed at most. A dusting of legume inoculant on the roots at planting sets it up for sturdier, better-performing plants.
Pruning
Deadhead the spent spires as they fade to draw out a second flush, hold the plant's vigor, and keep self-seeding in check. Once flowering slows, cut the tired foliage back to keep the clump neat in the border.
Size & spacing
Lupine reaches 3 to 4 feet (91 to 122 cm) in bloom and forms a clump about 12 to 18 inches (30 to 46 cm) across, so it sits comfortably mid-border. Give each plant that room so air moves through and mildew stays off the display.
When to plant
Lupine keeps to a cool-season rhythm that fits neatly into the gardening year. Sow seed in fall or start it indoors in late winter, settle the plants into their bed in spring once frost has passed, and the spires open from May into July for that first flush of summer color.
Northern hemisphere
Southern hemisphere
Typical months for a temperate climate: start earlier in warm zones, later where spring frosts linger.
- Sow: 6 to 8 weeks before last spring frost; nick/scarify and soak seed to aid germination
- Plant: Spring after last frost, or sow seed in fall
- Harvest: May to July
Hardiness
USDA hardiness zones: 4–8
Temperature: down to -34°C
Troubleshooting
Lupine asks little and mostly holds its poise, though a few familiar issues can dull the leaves and the rising spikes. Caught early, they rarely spoil the picture. Match what you see below, then set it right before it spreads through the planting.
A pale bloom dulling the foliage in the border
That soft grey cast is powdery mildew, a fungus that creeps in wherever the air hangs heavy around plants set too close or tucked into shade. Open the planting up so light and air reach the leaves, keep water to the base of the clump, and clear away the worst-marked foliage to restore the display.
Fix:
- Improve air circulation by thinning and spacing plants
- Avoid overhead watering
- Remove and dispose of badly affected foliage
A haze of tiny insects spoiling the rising spikes
Those clusters clouding the fresh shoots and forming spikes are aphids, drawn to the softest, most promising growth. A brisk jet of water clears the crowd, insecticidal soap settles any that linger, and resident lady beetles keep the balance. A restrained hand with nitrogen helps too, since a rush of tender growth is what tempts them in.
Fix:
- Spray plants with a strong jet of water to dislodge aphids
- Apply insecticidal soap if needed
- Encourage natural predators such as lady beetles
A once-lovely clump quietly bowing out
A fading clump is simply lupine keeping to its nature as a short-lived perennial, a run that hot, humid summers shorten further. Since the spires and vigor usually slip within 2 to 5 years, weave a few young plants into the scheme each season, favor a cool-summer setting or grow it as an annual where the heat presses, and let a little seed drop to renew the planting on its own.
Fix:
- Replace plants every few years
- Grow in cool-summer sites or treat as annual in hot zones
- Allow some self-seeding or start new plants from seed
Young leaves left torn and ragged by morning
Ragged edges and a faint silver shimmer point to slugs and snails, quiet night feeders with a taste for tender seedlings. Gather them by torchlight or draw them to traps, sweep away the damp litter and heavy mulch that shelters them near the crowns, and edge the planting with a barrier or iron-phosphate bait to keep the young growth intact.
Fix:
- Hand-pick at night or set out traps
- Reduce damp hiding spots and mulch buildup near crowns
- Use barriers or iron-phosphate baits
Toxicity
For all its beauty, lupine is a poisonous plant and deserves to be sited with that in mind. Every part holds quinolizidine alkaloids, densest in the seeds and pods, and grazing animals pay the steepest price. Pregnant cattle face the worst of it, since the teratogen anagyrine causes crooked calf disease, and no part of the plant is safe for people to eat off the stem.
Toxic to
Cats · Dogs · Horses · Rabbits · Livestock · Birds · People
Cats Toxic
Set the border where a roaming cat cannot browse it, since the quinolizidine alkaloids unsettle a cat's stomach and bring vomiting and diarrhea. A larger taste, the seeds most of all, can carry on to drooling and tremors.
Dogs Toxic
A dog that samples lupine usually meets vomiting and diarrhea first. Because the seeds hold the heaviest alkaloid load, a larger mouthful can leave a dog agitated, trembling, and unsteady on its feet.
Horses Severe
Horses fare badly on the alkaloids, which bring muscle weakness, a wavering stagger, and other nervous signs. The seeds and pods are the most dangerous parts and belong nowhere near their feed or grazing.
Rabbits Severe
Lupine is no safe forage for rabbits. The same quinolizidine alkaloids that fell larger grazers reach a rabbit's small frame as well, so keep the leaves, seeds, and pods far from them.
Livestock Severe
In cattle, sheep, and goats the alkaloids bring muscular weakness, ataxia, and nervous signs. The gravest danger falls on pregnant cattle grazing lupine across gestation days 40 to 100, when the teratogen anagyrine causes crooked calf disease, with skeletal contracture deformities and the occasional cleft palate.
Birds Severe
The alkaloid-laden seeds and pods poison birds, and the rest of the plant offers no safer bite. Keep poultry and pet birds clear of lupine altogether.
People Caution
No part of garden lupine belongs on the table without care. The bitter seeds brim with alkaloids and turn edible only after a long soaking and debittering, so treat the whole plant as ornamental and keep children from tasting the pods.
Keep grazing animals, especially pregnant cattle, away from lupines; seeds and seed pods are the most alkaloid-rich parts.
Helpline numbers
United States
ASPCA Animal Poison Control: (888) 426-4435 (fee applies)
Poison Control: (800) 222-1222
Canada
Poison Centres: 1-844-764-7669
Varieties
Most garden lupines come from a handful of well-loved strains and selections. These are the ones that turn up most often in a planting plan.
Russell Hybrids
George Russell's classic strain crowns the border with tall, densely filled spikes in both bicolors and solid tones, though seed saved at home will not return the same plant.
The Governor
This bushy Russell-type selection earns its place with crisp blue-and-white bicolor spikes.
Manhattan Lights
A compact hybrid that lifts purple-and-yellow bicolor spikes on trim, upright stems well suited to smaller schemes.
How to propagate
Lupine is grown almost entirely from seed, though the hard coat wants a little help before it will break into growth.
SeedModerate
Sow in fall, or start indoors 6 to 8 weeks before last spring frost · Blooms the first or second year from seed depending on sowing time
Lupine rises willingly from seed once the hard coat is coaxed open. Nick or scarify each seed and give it a soak before sowing, then dust the roots with legume inoculant to ease the young plants into their place. Sow in fall or start indoors 6 to 8 weeks before the last frost, and look for the first spires the first or second year according to when you sow. Keep in mind that hybrids will not return true from seed saved in the garden.
Myths
Lupines are deadly to dogs and cats, so any contact is an emergency.
For a household dog or cat, a nibble of lupine tends to end at vomiting or diarrhea and little more. The grave danger sits with grazing livestock, above all pregnant cattle, where the alkaloids cause poisoning and the teratogen anagyrine triggers crooked calf disease.
You can save seed from Russell hybrid lupines and get identical plants.
Seed gathered from a hybrid scatters into a mix of unpredictable seedlings rather than copies of the parent you admired. Only purchased seed or vegetative propagation reliably returns a named strain to the border.