How to Plant, Grow, and Care for Texas Bluebonnets (2024)

Stunning springtime displays of bluebonnets look like a blue blanket of blooms across Texas landscapes. This iconic state flower has vivid blue flower spikes of pea-shaped flowers with icy-white tops. From open pastures to native prairies to rolling roadsides, these wildflowers willingly grow almost anywhere in the Lone Star State, including your garden! Bluebonnets have a reputation for being tricky to establish, but with some patience and a little planning, you can grow a stand that will bloom for years to come.

This hardy lupine variety is drought-tolerant, low-maintenance, and leguminous. This means bluebonnets work symbiotically with soil bacteria to fix nitrogen, essentially creating their own fertilizer. Moreover, bluebonnets eagerly grow in poor, disturbed soils. They don’t mind clay, rocks, alkalinity, or long periods without water, and their seeds can lay dormant for years, waiting for the right conditions.

However, these robust mechanisms for survival also mean you need a bit of preparation to get the seeds to germinate. Let’s dig into the best tips and tricks for planting and growing a lush stand of Texas bluebonnets.

Bluebonnet Overview

Plant Type Annual wildflower Plant Family Fabaceae Plant Genus Lupinus Plant Species texensis Hardiness Zone 4-8 Planting Season Fall, early spring	Plant Maintenance Low Plant Height 12-24” Fertility Needs Low Temperature 55-70°F (13-21°C) during blooming, tolerate frost to 20°F(-7°C) Companion Plants Indian paintbrush, winecups, coneflower Soil Type Well-drained	Plant Spacing 12-18” Watering Needs Low Sun Exposure Full sun Lifespan Self-seeding annual Pests Aphids, grasshoppers Diseases Root rot (particularly in poorly drained soil)

History and Cultivation

Bluebonnets were named the Texas state flower in 1901. The state legislature specifically chose the species Lupinus subcarnosus (the sandyland bluebonnet), but citizens debated and campaigned for decades to name Lupinus texensis the official state flower. As of 1971, all six native species of bluebonnets that grow in the Lone Star State are often collectively considered the state flower.

During the 1930s, the Highway Department began a large-scale beautification program to extend the state flower’s range and plant the blue blooms along almost all major highways. You can now see the wildflowers bursting into bloom from March to April all across Texas.

Contrary to popular belief, you don’t have to live in Texas to grow bluebonnets. This lupine wildflower is widely adaptable throughout the southern U.S., including Oklahoma, Louisiana, and Florida. The plans are resilient in a variety of conditions, and many species of the Lupinus genus naturally cross together.

Why Are Bluebonnets Special in Texas?

The bluebonnet is the state flower of Texas because the wildflower naturally blankets open prairies, fields, and roadsides across the state’s diverse landscapes. This species is native to Texas, particularly limestone outcroppings and poor clay soils.

The rugged drought tolerance and low-maintenance resilience of this flower symbolize Texas’ independent spirit. The robust, gravel-like seeds are a testament of Texan toughness.

How Many Species of Bluebonnets are the Texas State Flower?

There are technically six species of Texas bluebonnets, all members of the Lupinus genus, with the signature blue-hued flower spikes and palmately compound silvery-green leaves. All of these wildflowers grow in different regions of Texas and prefer similar conditions.

Originally, only Lupinus subcarnosus was considered the state flower. But, after a public debacle with the state legislature in the 1970s, six native species of lupines were collectively designated the Texas state flower. They include:

• Lupinus texensis: This is the most iconic, vibrant bluebonnet commonly sold for landscaping and roadside plantings.
• L. subcarnosus: The sandyland bluebonnet grows mostly in deep sands of south-central Texas.
• L. havardii: Also known as Big Bend bluebonnet, this species is much taller, up to 1-3 feet.
• L. concinnus: The annual lupine is smaller (2-6 inches), sprawling, and has purplish-red flowers.
• L. plattensis: Sometimes called the dune bluebonnet, this species grows from northwest Texas up to Montana and Nebraska. It has a noticeable dark spot on each blue flower.
• L. perennis: The perennial bluebonnet is fairly rare but thrives in Big Thicket woodlands and states east of Texas.

This guide will mostly focus on L. texensis, but you can adapt the growing methods to any bluebonnet species.

Are Bluebonnets Related to Lupines?

All bluebonnets are lupines and members of the Lupinus genus. These nitrogen-fixing wildflowers belong to the plant family Fabaceae (the pea and bean family). They are relatives of garden green beans and chickpeas, as well as leguminous trees like mesquite and acacia.

Propagation

Bluebonnets are notoriously resilient, but they take time to form dense colonies of growth that bloom into blue blankets in spring. Many gardeners have difficulty germinating these finicky wildflower seeds because they aren’t in tune with the plants’ cycles in the wild. Here, we’ll demystify the secrets to successfully germinating bluebonnet seeds in any garden.

Seed

The best time to sow bluebonnet seeds is in early October or November. You can plant bluebonnets in spring, but you will be far more successful if you plant in fall. If you observe the lifecycle of these self-sowing annual plants in the wild, you can understand why it’s best to sow the seeds in autumn.

Wild lupine plants flower in spring, then produce pea-pod-shaped seed pods in summer. As the pods mature and dry, the seeds naturally fall to the ground in fall and germinate in the cool moist weather. This cool-climate annual grows steadily throughout the winter or goes dormant in areas with harder freezes. In spring, the new generation of bluebonnets flowers once there is enough water and warmth to stimulate blooms.

Then, the cycle repeats. The green seed pods turn yellow and then brown as they mature. They eventually burst open to release the tiny, hard seeds. The flattened seeds of a bluebonnet look like pea-gravel; and they truly are tough as rocks. The hard seed coat sometimes needs to be scarified.

Scarification

The extremely hard seed coating on lupine seeds is nature’s insurance policy to protect the seeds if there is a particularly dry year without enough water to germinate them. The hardened coat can allow the seeds to lay dormant in the soil until the following year. Over that time, weather and abrasive forces naturally wear down the seed coat so it can germinate the next time conditions are favorable.

This survival mechanism is amazing for ensuring the proliferation of wild plants, but it is the reason that many gardeners struggle to establish strong stands of bluebonnets in the first few years. To increase germination, you can try scarification. This is a fancy word for simply scraping or scratching the seed coats to mimic the weathering process that would happen in nature. Once you knick the seed coat, most seeds will germinate quickly if they have enough moisture.

All of these methods signal to the hardy seeds, “Wake up! It’s time to germinate!” But you must plant the seeds quickly after scarification and provide them plenty of moisture to ensure they sprout.

If you are planting in spring, scarification can speed up the process. But if you are planting in fall and you don’t plan to irrigate your bluebonnet patch, scarification isn’t necessary. It’s better to leave the seeds to awaken with nature once there is enough moisture.

Seeding Depth

Like most wildflowers, lupines are best sown close to the soil surface. Cover the seeds with no more than ⅛ to ¼ inch of soil. They should not be planted too deep, or they won’t germinate. However, you still want to check that the seeds have some seed-to-soil contact. If you only sprinkle them on top of the dirt, birds may eat them or the seeds will be blasted with sunlight.

For small plantings, simply press the seeds into the soil and lightly sprinkle with compost or vermiculite over top. For larger plantings, broadcast the seeds and rake into place. If you plant before a rain, this can help the seeds settle into the ground.

Planting

Texas bluebonnets have evolved to thrive in the Hill Country’s disturbed, rocky, poor soils with alkaline pH and frequent droughts. While it may be tempting to plant them in compost-rich beds, you can save your garden amendments for vegetables and other crops.

You don’t need to prepare a fancy seedbed. Instead, choose an open, sunny location with relatively poor soil and clear away any weeds. Broadcasting over the disturbed area is simple and straightforward. Be sure to rake the seeds in and water thoroughly after scattering.

If you want to establish bluebonnets on a grass lawn, first mow the lawn as low as possible and rake away excess thatch. Seed-to-soil contact is very important, so you must remove any debris that can inhibit the seeds from actually touching the dirt.

Spacing

Lupines naturally grow in dense colonies, so precise spacing is not necessary. If you want a more manicured flower bed, plant two to three seeds every 10-12 inches and thin to one strong plant per foot. When growing companion plants nearby, provide at least 12 inches of space between the neighboring plants.

Rhizobium Inoculation

Bluebonnet roots work symbiotically with root-dwelling bacteria called Rhizobium. The bacteria form nodules on their roots where they convert atmospheric nitrogen into plant-available nitrogen. This process is called nitrogen fixation and is the hallmark of the Fabaceae (legume) plant family. The symbiosis ensures strong plant growth and abundant flower production.

However, if the soil doesn’t have naturally occurring Rhizobium, you may need to inoculate it to improve the growth of your bluebonnets. If a stand is taking several years to establish, gently uproot a plant and investigate the roots. If you see small rounded lumps (nodules) attached to the roots, this likely means that the symbiotic bacteria is already growing and needs more time to establish.

But if your plants are lacking root nodules, you can apply a store bought inoculant to the soil or to new seeds before planting. Most inoculants come in powder form. Apply the bacteria to damp seeds and shake them together to ensure a strong coating. Then plant as usual.

Do Bluebonnets Transplant Well?

Bluebonnets are best grown from seed, but you can also find established seedlings at local nurseries. The transplants are a good option for anyone who is planting late or wants to quickly fill a bed.

However, you should not transplant bluebonnets when they are actively blooming or seeding. These hardy perennials need to be moved only when they are dormant, preferably in late winter or early spring. Growing from seed is a more reliable and affordable way to establish this wildflower.

How to Grow

Once established, bluebonnets don’t ask for much. They enjoy bad soil, lots of sun, and only occasional water. The only thing they despise is overcrowding and competition from nearby plants. If you get your Lone Star wildflower patch past the seedling stage and keep them weeded, you are already on the path to success! The blue blooms should get brighter and more abundant every year.

Light

Most wildflowers thrive in full sunlight, and lupines are no different. These early spring bloomers enjoy open prairies and fields where they can bask in six to eight hours (or more) of direct sunlight per day. If you grow them in the shade, you may not get to see the iconic blue flowers.

Water

The Lone Star State flower is ruggedly drought-tolerant. Supplemental watering is only important after planting. You must keep newly sown seeds moist for the first few weeks. The soil should be moist but never soggy. If it rains, the bluebonnets will naturally establish and you don’t have to worry about irrigation.

Soil

Unlike most garden plants, poor soil is important for these wildflowers! They truly enjoy rocky, lean soil and thrive where most plants won’t grow. They can tolerate sand, clay, or even decomposed granite. The rugged roots are willing to reach into nearly any soil surface, even if it is compacted.

However, if your soil is almost pure sand, consider seeking the native sandyland bluebonnet (L. subcarnosus) rather than L. texensis. As a general rule of thumb, most yards and roadsides with other types of poor soil can be sown with L. texensis.

Climate and Temperature

This iconic Texas flower does not mind the cold. It is hardy in zones 4-8. The seeds usually germinate in late fall and overwinter with a small rosette. Because they are annuals, lupines can withstand colder winters while their seeds or seedlings go dormant below 20°F (-7°C). They are adapted to cold snaps throughout Texan winters. Sometimes, you can find the pretty circular leaf clusters covered in ice crystals.

Fertilizing

Do not apply fertilizer to your wildflower patch! These lupines thrive in poor soil and do not need any supplemental nutrients. They have grown wild throughout the Texas countryside for hundreds or thousands of years without human assistance.

Bluebonnets have a symbiotic relationship with nitrogen-fixing bacteria that take care of their nutrient needs. The deep taproots are accustomed to finding any other nutrients and minerals they need in their native soils. In fact, they naturally enrich the soil for neighboring plants.

Maintenance

Weeding is the most important maintenance for your bluebonnet patch. These flowers take off growing in early spring and dislike competition. In the early years of establishing a patch, it’s important to keep other plants at a distance. You can hand-pull any weeds within 12-24” of lupine plants, and mow surrounding grass very low in late summer so the new seeds can scatter and germinate in the vicinity.

Another important aspect of growing bluebonnets is seed collection. This is a great practice for controlling the spread of your patch. If you don’t mind bluebonnets bullying plants around their initial area, there’s no need to do this. But if you’d like to keep them in one area, collect their pea-like seed pods at the end of their blooming season.

Varieties

You may notice that some bluebonnets are white, pink, or maroon. Mutations and hybridizations naturally happen in the wild, and genetics from other species of lupine can be crossed into your stand via the pollination powers of local bees and butterflies. While Lupinus texensis is the most common and iconic bluebonnet, the other five Texas native state flowers are worth noting:

Lupinus texensis

This iconic blue lupine is the most commonly sold wildflower seed for landscaping and roadside plantings. The Texas Department of Transportation buys over 30,000 pounds of this wildflower seed every year and sows it along major roadways throughout the state. Because the plants thrive in disturbed or degraded soils, they are perfect for recolonizing areas that were over-grazed or burned by wildfires.

These wildflowers are particularly important for native bees and butterflies. They are the larval host plants for the Hairstreak and Elfin butterflies. Blooms also attract beneficial insects.

Sandyland Bluebonnet (L. subcarnosus)

The sandyland bluebonnet grows mostly in deep sands of south central Texas. It is a smaller species with less showy flowers, but it was the first bluebonnet designated as the state flower in 1901. This species averages 6-16 inches with brighter blue flower spikes.

The white center of the flowers usually turns purple after pollination and aging. The palmate leaves have five leaflets. The sandyland lupine usually grows alongside paintbrushes in wildflower clusters along roadsides.

Big Bend Bluebonnet (L. havardii)

Also known as Big Bend lupine or Harvard bluebonnet, this species reaches up to 3 feet tall when flowering. The extra large flower spikes cover the top four to eight inches of the stems. This winter annual has extremely deep blue blooms with a blotch of yellow in between each individual blossom. The leaves are palmate with seven leaflets, often looking like little hands branching out from the bottom of the shrubby mass of growth.

Lupinus concinnus

Sometimes called Bajada lupine or Nipomo Mesa lupine, this annual bluebonnet is quite small, averaging two to six inches tall. It can be upright or sprawling and yields purplish-red pea-shaped flowers that have white spots in the center. The wild plants are concentrated in southwest Texas desert areas and into New Mexico, Arizona, Nevada, and Utah. They are best for sandy soils.

Dune Bluebonnet (L. plattensis)

Sometimes called the Nebraska lupine or dune bluebonnet, this species grows from northwest Texas up to Colorado, Montana, and Nebraska. The flowers are lighter blue with a dark spot or “eye” in the middle of each flower, giving them a shimmering effect from a distance. They bloom a bit later, in April through June.

Lupinus perennis

The perennial bluebonnet is fairly rare, but thrives in the Big Thicket woodlands and states east of Texas. The elongated flowers bloom on one to two foot stems. They can be blue, purple, pink, or white. The palmate leaves have 7-11 leaflets.

The genus name Lupinus comes from the Latin word lupus, meaning “wolf.” Botanists once believed that lupine plants devour or “wolf up” the mineral content of soils, leading to the proliferation of large colonies and depletion of other plants. Modern science has proved that the plants actually enrich the soil thanks to their symbiosis with root-dwelling nitrogen-fixing bacteria.

The perennial lupine is particularly adept at improving soil fertility. It also can tolerate more shade than other species, often growing in open woodlands. This bluebonnet has the largest native range, covering most of the United States east of the Mississippi River. It is very cold- tolerant and prefers better drained soil. It is the larval host for the Karner Blue butterfly and Frosted Elfin butterfly.

Garden Design

The plants that grow with bluebonnets on Texas roadsides are clearly their best companions in the garden. Choose native wildflowers that prefer full sun and tolerate poor soil.

Indian Paintbrush (Castilleja indivisa)

The Lone Star State flower’s most recognizable comrade is Indian paintbrush. This colorful red and yellow spiked flower is annual or biennial, growing 6-18 inches tall. It prefers the exact conditions as lupines and blooms from single, unbranched stems. The color contrast of red against blue blooms creates a patriotic and intriguing garden display that reliably returns every spring.

Winecup (Callirhoe involucrata)

The purple poppy mallow is sometimes called “winecup” because the flowers are shaped like little cabernet-colored cups. The stems are sprawling and form thick mats, growing to just 12” tall. They make a lovely ground cover or bedding plant near bluebonnet beds. Winecups are extra drought-tolerant and look very nice dangling over a retaining wall.

Coneflower (Echinacea purpurea)

This easily recognizable perennial wildflower is native to most of North America. It doesn’t mind the disturbed spots where lupines grow. The intriguing flower petals droop downward, revealing a spiny brown central flower disk.

Hummingbirds and bees love this plant. Echinacea will naturalize in your yard alongside bluebonnets. In a confined space, plant coneflowers farther back on the northern side so your lupines don’t get shaded.

Pests and Diseases

Lupines mostly fend for themselves, but they can get attacked by a few pests and diseases you should be aware of.

Aphids

You mostly find aphids (and occasionally spider mites) on bluebonnets that are under extreme drought stress. On the flip side, if you accidentally plant the flowers in overly fertilized soil, they may experience a burst of foliage growth that is more susceptible to pest infestation. The sugary trails left behind this sap-sucking pest can attract ants. A strong blast of water is usually enough to knock aphids off the leaves.

Caterpillars

Bluebonnets are the larval host plants for many species of native butterflies, so you may notice caterpillars munching away on the foliage. Do not mess with them or remove them! This is a natural ecological interaction. While it may seem like your flowers are being damaged, rest assured that the plants will regenerate and butterflies will eventually pupate.

Birds

Birds are a major pest of bluebonnet seeds and only pose issues when you are first sowing a new patch. This is easy to avoid by slightly burying the seeds beneath about ¼ inch of soil. However, be sure you don’t bury the seeds too deep, or they won’t germinate.

Root Rot

This wildflower is adapted to dry Texas soils, so waterlogging can cause some issues. While the plants don’t mind poor soil, they cannot handle excessively wet soil. If the ground is waterlogged for long periods of time, the roots may rot. Avoid over-watering or excessively irrigating the plants. If they show signs of wilting (in spite of wet soil), you may need to amend with sand or gravel, or replant in a better drained location.

Plant Uses

Bluebonnets are strictly ornamental and wildlife-friendly flowers. They cannot be eaten. All parts of the plant are toxic, especially the seeds and pods. Do not allow children, pets, or grazing animals like cows and horses to eat lupines. Fortunately, they usually avoid the plants on their own.

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