How to Plant, Grow and Care For Lupine Flowers

Beautiful, yet controversial. That seems to be the resounding thought around the thrilling–sometimes poisonous and invasive–lupine flower. Their blooms are exquisite–so much so that they’ve inspired festivals. Some gardeners have trouble keeping them as a perennial in their garden, while in other areas ornamental lupines have escaped and proliferated into the wild, to the point where they’re considered invasive.

Lupines (or lupins), also known as wild peas, blue peas, quaker bonnets, sundials, and bluebonnets (specifically in Texas), are members of the pea (or bean) family—Fabaceae. There are around 200 species in the genus Lupinus. These perennials flower in blue and purple, but you’ll also see yellow, red, white, and bicolors.

If you’re ready to take your garden to the next level, then lupines may be for you as they require a little bit more effort to get them going. Read on to learn all about lupine flowers and how to grow them in your very own garden!

Plant Description

Lupines are considered annual or herbaceous short-lived perennial plants. They grow from the crown of a taproot. Leaves are palmate (palm-shaped) with finger-like segments. Some leaves may be hairy or silky and have a silver or gray-green appearance.

They grow anywhere from 10 inches to 2 feet tall when mature. They bloom from June to August, typically. The flowers resemble pea flowers. These short lived perennials bloom in purple, blue, red, yellow, pink, and white. The flowers are often bi-colored. Flowers are arranged on an erect spike.

The flowers produce seed pods, similar to a pea pod. The pods are typically hairy and somewhat flattened. When they mature they turn grayish-brown. Each pod will contain approximately 12 seeds.

Because lupines are considered legumes, they have nodules on their roots that contain nitrogen-fixing bacteria. These bacteria form a symbiotic relationship with the plant.

In exchange for nutrients and a space to live, the bacteria take ammonia gas from the air and convert it into a form of nitrogen that can later be taken up by plants. For this reason, they have long been touted to improve soil fertility.

Propagation

Lupines can be propagated by seeds, basal cuttings, or division. Seeds propagation is the recommended option as it is the easiest and most common way to propagate lupines.

Propagating From Seed

Lupine seed requires a few extra steps in order to germinate. Seeds either need to be scarified and soaked in water for a short period of time, or seeds can be soaked only for a longer period of time.

To scarify seeds, this means you need to nick the hard seed coat to allow water to penetrate the seed. This simulates the freezing and thawing process that would regularly occur in nature. You can rub the seeds gently on a piece of sandpaper or nick the seeds with a knife to accomplish scarification.

After scarification, soak lupine seeds in water. Only soak the seeds for enough time that the seed begins to plump up.

If you choose to skip scarification, you may soak the seeds in water for 24 hours.

Seeds require darkness to germinate. Bury seeds at least ½  inch below the soil surface. Lupine seeds require soil temperatures between 55 and 60℉. They will germinate sporadically, anywhere from 2 weeks to 2 months after sowing.

Propagating via Cuttings

Lupine can be propagated by basal cuttings, too. Once new growth has emerged from the crown and has reached at least 6 inches long, you can take a cutting.

Cuttings are very prone to wilting, so cut off at least half of the leaf and place in a sterile, loose potting mixture. Keep temperatures between 60 and 65℉.

Lupine cuttings are extremely sensitive to fungal infections. Make sure all knives, clippers, pots, and trays used for cutting propagation are clean and sterilized before taking cuttings.

Propagating via Division

Propagating lupines by division is rarely performed, if at all. They hate any sort of root disturbance. In fact, some sources say you should avoid dividing them altogether.

According to The Plant Propagator’s Bible by Miranda Smith, if you choose to propagate via division, wait until after the plants have already bloomed to divide. Divide the fleshy crown so that you have at least 3 growth buds on each division. Use a sharp, sterile knife to divide.

Again, division is an absolute last resort for lupines.

When to Plant

Plant seeds in the early Spring about a month prior to your last estimated frost. In warmer climates, you may choose to sow in the Fall in an unheated greenhouse or tunnel.

Lupines do not like root disturbance! It is best to either direct sow into the garden or transplant before roots outgrow plugs or pots.

Space plants 2 to 3 feet apart for large varieties and 12 to 18 inches apart for smaller varieties.

How to Grow

Once you’ve decided to grow lupines in your garden, it’s best to ensure that you meet all their needs for healthy growing plants. You’ll want to make sure you place them in the right location, and plant them in the correct soil type. You’ll also need to ensure they have adequate sunlight, and water. Let’s dive in a little deeper and look at all aspects of their growth.

Location

These short lived perennials prefer to grow in full sun (at least 6 to 8 hours of direct sunlight per day) or part shade (4 to 6 hours direct sunlight). Choose a wide open location away from sun-blocking trees and shrubs if possible.

If you plan on planting quite a few of them together, make sure to allow enough room for them to spread out and grow to their fullest potential.

Soil

Lupines require well-drained, coarse soils to grow properly. Many wild lupines grow in sand prairies, sand savannas, and sandy lakeshores.

Choose an area of your garden that has a sandier texture or plant in raised beds to promote good drainage. They prefer soils that are slightly acidic.

Water

Lupines have moderate moisture requirements. Having adapted in sandy soils, they definitely cannot withstand waterlogged conditions. Let the soil dry out between waterings. Usually, you will only need to water if you are having an ongoing dry spell or drought.

Do not allow for waterlogged soil. This can be a breeding ground for disease. Even though lupine can tolerate even low quality soils, they should still be well draining to avoid problems.

Climate and Temperature

Many varieties are short-lived perennials in USDA Hardiness zones 4 through 8. Some that act as annual flowers will readily reseed and spread given the right circumstances.

Lupines like the cool temperatures of Spring, so they do not thrive in very warm climates. Treating them as a hardy annual instead of a perennial in warmer climates may be ideal. Hardy annuals are plants that can typically be sown in the Fall and overwintered.

Fertilizer

Lupines need little to no fertilizer to thrive. Wild lupines are known for colonizing areas with very poor soil fertility. Because they are leguminous plants, they “create” their own nitrogen via a symbiotic relationship with soil bacteria.

N₂ gas from the air is converted into plant-usable nitrogen in the nodules on lupine root systems which house the bacteria. Because of this characteristic, many have said that lupines are considered plants that build soil fertility.

Maintenance

If you’ve directly sown the seed outside (or allowed lupines to reseed), then thin seeds after true leaves appear on the seedlings for adequate spacing between plants.

If you don’t want your plants to reseed, cut off the faded blooms. When the plant starts to turn yellow and die back, lupines can be cut to the ground to overwinter.

Harvesting For Cut Flowers

Harvest lupines for cut flower arrangements when 80% of the flowers are open on the spike. Lynn Bcyzinski, author of The Flower Farmer: An Organic Grower’s Guide to Raising and Selling Cut Flowers, explains that putting lupines in cold water while also misting the flowers with cold water will help keep buds from shriveling after harvest.

She also mentions that some growers will prick the stem, flip the flower upside down, fill the stem with water, and plug the hole with a piece of cotton in order to extend vase life. What lengths you are willing to go to for this flower are up to you!

Collecting Seeds

After your lupines have bloomed, you’ll notice small green pods beginning to form where the blooms once were.

Once the pods turn from green to grayish-brown, you know it’s time to collect seeds. Pluck pods off the stalk and crack them open with your fingers. The seeds should readily fall out.

You’ll know you’ve harvested too early if the seeds are still green on the inside of the pod. Usually, the seeds will be black when mature. You’ll notice the stem will also be turning brown when seeds are mature, and the seeds will rattle in the pods if you shake the stem. 

Popular Varieties

There are many popular species and varieties of this plant. As mentioned earlier, blue and purple shades are the most common.

Wild lupine (L. perennis) is native to the U.S. from the east to Midwest. Many populations of wild lupine have declined, but there are still some areas where wild lupines can be found.

Russells’ Hybrids lupines (L. polyphyllus) are considered the best of ornamental varieties sold from seed. They are an interspecific cross developed by George Russell in the early 1900s. They are considered the longest-lived and most cost-effective, even compared to many modern patented varieties.

‘Woodfield Hybrids’ (L. polyphyllus) are known for their extra dense, tight, large-flowered spikes. The color mix comes with different color combinations as well as single colors of pure white, pink, red, yellow, orange, blue, and violet.

Texas bluebonnets (L. texensis) are considered some of the most famous lupines in the world. They are known for carpeting vast areas along roadside and hills in Texas every April. Festivals and special events celebrating these bluebonnets are common when the wild forms bloom.

Trademarked Varieties

Some popular patented or trademarked varieties are:

Staircase™ series, which comes in shades of red, orange, yellow, and blue. This series is considered half-hardy perennials, meaning they will not come back or will have severely reduced vigor after a few years.

Westcountry™ series, which comes in varieties of ‘Masterpiece’, ‘Red Rum’, ‘Blacksmith’, ‘Terracotta’. These varieties are all patented so they must be vegetatively propagated. You will not find seed for this series. Again, Westcountry™ lupines are considered half-hardy perennials.

Common Pests and Diseases

Lupines can be very susceptible to particular fungal diseases if propagated by cuttings. Always use clean, sterile equipment when taking cuttings.

Anthracnose

This is a disease which causes rotting of the root system and ultimately wilting and death of the plant. Young plants are most susceptible. Cool, moist conditions favor anthracnose and other soil pathogens.

Aphids

Aphids are very small insects with piercing, sucking mouthparts that transmit viruses and cause stunting, deformity, and overall yellowing and reduced vigor of the plant. Once you see a few there’s likely hundreds. They may be any shade of green to gray to black and can reproduce rapidly.

Spray any infected plants with a forceful stream of water to knock off aphids. If I have a severe aphid infestation on a particular plant, I will typically remove that entire plant from my garden.

You can also invest in beneficial insects like lady beetles or lacewings, but if you are growing outside rather than in a greenhouse or unheated tunnel, releasing these insects may not make a difference.

Powdery Mildew

is a fungal disease that causes a powdery, whitish film on the leaves of the plant. Severe infections will result in yellowing of leaves and leaf death. Increasing your air flow throughout your garden by increasing spacing between plants will help reduce powdery mildew incidence.

Also, do not use overhead watering to water your plants. Water at the base of your plants instead so that there is a limited amount of time that the water remains on the plant foliage.

Plant Uses

Lupines are mostly used as ornamental flowers in landscaping, as specimens in native planting, or as cut flowers. They also attract a large number of bees, and birds, especially game birds, which eat the seeds. Hummingbirds also love them.

Some lupines can be poisonous to cattle and should not be planted near where cattle will graze. Poisoning can cause blindness, convulsions, and heavy or labored breathing. Sheep are also mildly affected by lupine poisoning, but symptoms may be delayed by up to 24 hours.

In some pregnant animals, lupines can cause “crooked calf” disease if consumed between the 40th and 70th day of gestation. Crooked calf disease is characterized by deformities and twisted limbs in calves.

For this reason, in many places that lupine grows wild, like on the western grazing ranges of the U.S, lupines are considered a harmful weed.

However, extracts from lupine plants have been made to produce medicine that manages cardiac arrhythmias. Many low-alkaloid containing species have been grown over time as fodder for animals, green manures, and even human consumption in ancient times.

DO NOT expect that your ornamental lupine specimens can be eaten. In general, lupine is considered to be poisonous to humans.

Frequently Asked Questions