Have you ever seen a prairie dotted with delicate, pale blue flowers? That may have been Blue Flax, or Linum lewisii. It’s a hardy yet beautiful plant to witness in nature, and luckily, you can grow it in your garden as well. Here we’ll take you through everything you need to know about growing and caring for Linum Lewisii (Lewis Flax) at home including planting, soil considerations, light preferences, feeding, pruning, and over-winter care.

How to Grow & Care for Linum Lewisii (Lewis Flax)

How to Grow Linum Lewisii (Lewis Flax) – The Essentials: 

Botanical Name:Linum lewisii
Also Known As:Lewis Flax, Blue Flax, Prairie Flax, Mountain Flax
Hardiness Zones:USDA growing zones 3 to 9
Flowering Months: Late spring through mid-summer
Growing Difficulty:Easy. Great for beginners.
Type of Plant: Perennial herbaceous plant
Light Requirements:Bright, direct sunlight. Will tolerate partial shade.
Temperature and Humidity:Thrives in temperatures ranging from 65 to 70 degrees. However, this plant is hardy in cold conditions up to -20 degrees Fahrenheit and can tolerate various humidity levels. 
Watering Needs:Blue Flax will likely often get the water it needs from precipitation. The plant may benefit from occasional watering if rainfall drops below one inch per week.
Soil Preferences:Well-drained, moderately moist soil that is either slightly acidic, neutral, or slightly alkaline.
Feeding:Additional fertilization is not necessary with this plant.
Growth Expectations:Will reach between one to three feet tall, depending on growing conditions.
Toxicity:Non-toxic to humans and pets. However, it is not advisable to eat raw Lewis Flax seeds as they contain traces of cyanide.

About Linum Lewisii (Lewis Flax)

About Linum Lewisii (Lewis Flax)

Scientific Facts

Lewis Flax is also known by the species name Linum lewisii. This plant is a member of the Linaceae family and belongs to the genus Linum

Origins and History

Blue Flax is native to North America. The region where it grows natively spans from Alaska to Southern California and toward the Mississippi River. 

Interestingly, Prairie Flax was named for Meriwether Lewis. He was a North American explorer who led the Lewis and Clark expedition with William Clark.

Botanical Characteristics

Botanical Characteristics

Lewis Flax is an herbaceous plant that grows branching stems, narrow foliage, and small, delicate flowers. Its blooms are typically a pale blue color. However, this flower can also be lavender or white with blue veining. 

Uses and Benefits

While it’s not recommended to eat Blue Flax seeds raw, Native Americans once cooked them to drink in tea. Some tribes also used fibers from this species to make cords and rope. 

Today, growers around the world cultivate Flax plants to make linen and linseed oil. People also grow Blue Flax to attract pollinators like bees. Birds and larger animals enjoy eating this plant as well.

Bloom Time and Flowering Season

Bloom Time and Flowering Season

Lewis Flax blooms in late spring and has a shorter bloom time than other Flax varieties. Usually, its flowering season will last until mid-summer. 

Growth Expectations

Your Blue Flax plant will grow to be between one and three feet tall when it reaches maturity. It has a moderate growth rate compared to other species. 

Best Companion Plants in the Garden 

Linum lewisii’s easygoing nature makes it a great companion for other plants in your garden. It looks great when paired with different types of Flax, or perennials and annuals that highlight its unique color. Here are a few companion plants to consider for Lewis Flax.

  • California Poppies
  • Evening Primrose
  • Red Flax
  • White Gaura
  • Lavender
  • Golden Yarrow

How to Grow Linum Lewisii (Lewis Flax)

How to Grow Linum Lewisii (Lewis Flax)

Best Locations to Plant Lewis Flax

Blue Flax will bring a charming cottage aesthetic to open fields and garden beds. It makes a beautiful border plant with vivid flowers that bloom year after year. As long as you keep this species in a spot with full sun, it will grow happily in any outdoor space. 

What Are the Best Times of Year to Plant Linum Lewisii? 

The best time of year to plant Prairie Flax will depend on your location. In most locations, it’s best to plant this species in the early spring. However, if you live in a warmer climate, you can plant seeds as late as early fall. 

Growing from Seed vs. Planting Young Nursery Plants 

Growing from Seed vs. Planting Young Nursery Plants

Typically, gardeners prefer sowing Blue Flax seeds directly into the garden. This process is easier than transferring young nursery plants. 

This is because this plant can be challenging to transplant due to its fragile roots. Luckily, sowing the plant’s seedlings in your garden is a simple and rewarding process. 

What to Do Before Planting 

It’s almost time to plant your Lewis Flax. But first, you need to make sure the spot you choose gets plenty of full sun throughout the day. Make sure you have enough room to plant your seeds between four and six inches apart. 

Next, you’ll want to collect the important tools and materials for growing this species, like a gardening hoe and low-fertility soil. You’ll find a complete list of items and materials for planting Blue Flax in the Essential Tools section below. 

What’s the Best Soil for Lewis Flax

What's the Best Soil for Lewis Flax

Lewis Flax prefers well-drained, moderately moist soil. The species can handle various pH levels, from slightly alkaline to slightly acidic, and grows best in low-fertility soil. 

How to Plant Lewis Flax

Finally, the time has come to plant your Prairie Flax seeds. It’s easy to plant this species directly in your garden. Here are a few steps to keep in mind to ensure beautiful blue blooms. 

  • Rake the top layer of soil and remove grass or weeds. A spade or hoe may help in loosening the top few inches of earth.
  • Place your seeds on top of the soil around six inches apart. Do not press or cover your flax seeds, as the sun will aid with germination.
  • Keep the soil moist for a few weeks with regular watering. You can reduce watering once seeds have started to germinate. 
  • If you’re transplanting these seedlings, it’s best to do so while they’re still small. This will help avoid any harm to their fragile root systems. 

Light Preferences 

Light Preferences

Now, your Lewis Flax plants will do best in a spot that receives full sun throughout the day. But, this plant can also handle partial shade. 

Temperature and Humidity Preferences 

Linum lewisii enjoys temperatures ranging from 65 to 70 degrees Fahrenheit. However, this plant is as cold-hardy as they come. It can endure temperatures up to -20 degrees Fahrenheit.

Lewis Flax grows well in a variety of humidity levels and is tolerant of drought conditions. 

How to Care for Linum Lewisii (Lewis Flax)

How to Care for Linum Lewisii (Lewis Flax)

Watering Lewis Flax

The great news is your Lewis Flax plant will likely receive all the moisture it needs from precipitation. However, if rainfall drops below an average of one inch per week in your area, you may want to supplement with occasional watering. 

How, When, and Why to Fertilize 

Surprisingly, Lewis Flax won’t bloom as well in nutrient-rich soil. So, it is best to avoid fertilization altogether in most cases. If your soil is of particularly poor quality, you may want to apply a small amount of diluted fertilizer.

Pruning and Cutting Back

Pruning and Cutting Back

You may want to prune your Lewis Flax plant once it stops blooming in the fall. Use clippers or scissors to trim away old foliage and make room for new growth in the spring. 


You can easily propagate your Lewis Flax plant by seed. Harvest seeds from your plant once they’re ready and plant them in your garden, just as you did with the original plant. 

Conveniently, this plant will also self-seed. So, if you’re hoping to expand the plant, it will do the work for you without causing a disturbance in your garden.



Prairie Flax is cold-hardy, so you won’t need to worry about overwintering in most cases. However, if you’re concerned about lower temperatures, you can apply a minimal amount of mulch to the top of the plant’s soil. 

When and How to Transplant Linum Lewisii

Linum lewisii grows best when planted in the ground. But, some gardeners may start this species in small containers before transplanting. Since the plant has a delicate root system, it’s best to transplant before its roots fully develop.

You can also use peat pots for starting Blue Flax seeds. That way, you can move them to the garden without causing any disturbance to the roots. You can take the steps in the How to Plant section above to ensure your Lewis Flax seedlings thrive. 

Deadheading Lewis Flax

Deadheading is not a requirement when it comes to Lewis Flax care. Still, you may want to cut back spent foliage at the end of its growing season. 

Common Lewis Flax Problems and How to Treat Them

Common Lewis Flax Problems and How to Treat Them

Signs of Watering Issues

Linum lewisii is a drought-tolerant flowering plant, but it may face root rot just like many other species. If you notice a fungal infection, you will need to carefully remove the affected area and fill the area with fresh, clean soil. 

Signs Lewis Flax is Getting Too Little Light

Lewis Flax will bloom at its best when you plant it in a location with full sun. The best way to prevent stunted growth or poorly performing blooms is to plant your Flax seeds in a spot that gets full sun throughout the day. 

Common Pests and Diseases 

Unfortunately, there are a few garden diseases and pests you’ll need to look out for when it comes to Linum lewisii care. Here are some of the most common problems you may face with this plant. 

  • Flax bollworm
  • Aphids
  • Cutworms
  • Powdery mildew
  • Rust
  • Root rot

When it comes to pests, you will usually want to start by removing as many as you can by hand. You can use diatomaceous earth or an insecticide solution, depending on the pest.

If your Lewis Flax plant has a fungal issue like rust, root rot, or powdery mildew, you will need to remove the affected plants and soil as soon as possible. If any plants are salvageable, make sure to replant them in fresh, clean soil.

Essential Tools to Have Around

Essential Tools to Have Around

Here is our complete list of recommended tools and materials to have on hand for growing Linum lewisii. 

  • Cutting scissors
  • Well-draining soil
  • Mulch, if needed
  • A hoe or gardening spade
  • Diluted fertilizer, if needed
  • Insecticide
  • Diatomaceous earth
  • Container for collected seeds

Wrapping Up 

Perhaps now you’re envisioning meadows filled with Blue Flax flowers. It’s a great choice whether grown in your garden beds or an open meadow area. 

With these tips and suggested materials on hand, you can bring your vision to life and enjoy this perennial’s blooms year after year.

Flax Flower Growing and Care Guides:

For more, see our comprehensive guide to growing Linum Grandiflorum (Red Flax) at home.

Growing Linum Lewisii (Lewis Flax) FAQs

Yes, Linum lewisii is a hardy plant that can stand up to cold temperatures and drought conditions.

Linum lewisii will reach from one to three feet tall, depending on the growing conditions in your area.

To prepare Linum lewisii for winter, you can either allow flowers to wither naturally or trim them back for a tidier appearance.

No, Linum lewisii is not considered an invasive species.

Yes, Linum lewisii is a perennial herbaceous plant.

Yes, Linum lewisii will grow in partial shade. However, this species prefers to grow in full sun.

Now, Linum lewisii is not considered poisonous to humans. However, it is not recommended to eat Lewis Flax seeds raw, as they contain trace amounts of cyanide.

Contributing Editor | Full Bio | + posts

Brandy Wells is an American copywriter and content writer living in Spain. From hiking in her hometown near the Smoky Mountains to digging in the dirt in rural Oregon, she has always put a love of nature at the heart of her endeavors. These days, you’ll catch her writing content, and of course, taking breaks to tend to her growing houseplant collection.

Author Brandy Wells

Brandy Wells is an American copywriter and content writer living in Spain. From hiking in her hometown near the Smoky Mountains to digging in the dirt in rural Oregon, she has always put a love of nature at the heart of her endeavors. These days, you’ll catch her writing content, and of course, taking breaks to tend to her growing houseplant collection.

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