How to Grow Lewis Flax Flowers in Your Garden

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, I’ll take you through everything you need to know about growing and caring for Linum Lewisii, including planting, soil considerations, light preferences, feeding, pruning, and over-winter care.

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

Linum Lewisii Plant Care Basics

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:It thrives in temperatures ranging from 65 to 70 degrees Fahrenheit. However, it 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.

How to Grow Lewis Flax

A collection of thriving Linum Lewisii (Lewis Flax) plants in bloom showcase bright and vibrant blue flowers against green foliage and grass in the background

Best Locations to Plant

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. 

Best Times of Year to Plant

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 

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

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 must ensure the spot you choose gets plenty of full sun throughout the day. Ensure you have enough room to plant your seeds between four and six inches apart. 

Next, you’ll want to collect the essential 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. 

Best Soil Types

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

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 

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 various humidity levels and is tolerant of drought conditions. 

How to Care for Linum Lewisii (Lewis Flax)

A close shot of a blooming Linum Lewisii (Lewis Flax) plant with pale violet colored flowers and green foliage


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. 


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

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. 


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 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 Problems and How to Treat Them

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 must carefully remove the affected area and fill the area with fresh, clean soil. 

Lewis flax will bloom best when planted in full sun. To prevent stunted growth or poorly performing blooms, plant your flax seeds in a spot with 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

Regarding pests, you will usually want to start by removing as many as you can by hand. Depending on the pest, you can use diatomaceous earth or an insecticide solution.

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

Essential Tools to Have Around

A collection of garden tools

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

Growing Linum Lewisii (Lewis Flax) FAQs:

Are Linum lewisii (Lewis Flax) hardy?

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

How big do Linum lewisii get?

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

What do you do with Linum lewisii over winter?

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

Is Linum lewisii invasive?

No, Linum lewisii is not considered an invasive species.

Is Linum lewisii a perennial?

Yes, Linum lewisii is a perennial herbaceous plant.

Will Linum lewisii grow in shade?

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

Is Linum lewisii poisonous to humans?

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.

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.

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