Mertensia

( mur - TEN - see - uh )

At-A-Glance Information

This genus of flowering perennials commonly known as Bluebell, Oysterplant or Lungwort includes species which need partial to full shade and regular waterings for best performance in the landscape. Blooms pop early in the season, providing much-needed sustenance for hungry pollinators. Leaves are smooth and grey- or blue-green to true green. Flowers are bell-shaped and nodding, and their pink or lavender buds open to reveal blue flowers that are sometimes tinged with pink or purple. Mertensia are a great choice for woodland gardens, and do well in shady beds and borders. They can also be used as a spring groundcover or massed together, for erosion control, or simply as members of pollinator or wildlife gardens. Take care when planting these flowers in the landscape, as they are mildly toxic if ingested and have the potential to cause contact dermatitis in sensitive individuals.

Mertensia Species and Varietals

The genus Mertensia is a member of the plant family Boraginaceae and includes between 45 and 150 species. Plants in this genus are closely related to those in Myosotis (Forget-Me-Not), Pulmonaria (Lungwort), Symphytum (Comphrey) and Omphalodes (Navelwort). The Mertensia genus is named for German botanist Franz Carl Mertens. The best growing zones for Mertensia vary depending on the species. For more information, see the descriptions below. To find your zone, click here: Zone Map.

Mertensia bella (Beautiful Bluebells, Oregon Lungwort, Oregon Bluebells)
These plants are native to the northwestern United States, and prefers to grow in moist habitats. They produce clusters of bright blue bell-shaped flowers. Plants reach up to 20 inches tall when in bloom. Oregon Lungwort grows well in USDA hardiness zones 3-9.

Mertensia ciliata (Mountain Bluebell, Chiming Bells, Tall Fringed Bluebells, Streamside Bluebells, Ciliate Lungwort)
This species of Mertensia grows best in USDA hardiness zones 3-8 or Sunset growing zones 1-7 and 14-17 and is native to California, Nevada, Utah and Oregon. Plants reach three feet tall and about a foot wide. Flowers emerge blue and mature to pinkish-red. Blooms are fragrant.

Mertensia lanceolata (Prairie Bluebells, Lance-Leaved Bluebells, Lance-Leaved Lungwort, Narrow-Leaved Languid Ladies, Lance Leaf Chiming Bells)
This species is native to western North America and produces blue-green foliage. Flowering stalks are smooth and flower buds are pink-purple. Flowers are blue. In flower, plants reach between 4 and 18 inches tall. Lance-Leaved Bluebells grows well in USDA hardiness zones 3-8.

Mertensia longiflora (Small Bluebells, Long Bluebells, Long-Flowered Bluebells, Long-Flowered Lungwort, Trumpet Bluebells)
This species is native to western areas of North America, and forms a perennial herb with an erect blooming stem that reaches 8 inches tall. Flowers are tubular and hang from their attachments. Blooms are bright blue, but can also be lavender to pinkish or almost fully white. Small Bluebells grows well in USDA hardiness zones 3-7.

Mertensia maritima (Mertensia asiatica, Stenhammaria maritima, Mertensia simplicissima) (Oyster Leaf, Oyster Plant, Sea Bluebells, Gromwell, Sea Bugloss)
These plants are perennials that typically grow in coastal areas on gravelly beaches and are native to Britain and Northern Europe. They reach 20 inches tall when mature and in bloom, and produce clusters of reddish flowers that age to bright blue. Foliage is grey-green and smells like oysters when crushed, hence the plant's common name Oyster Plant. This species grows well in USDA hardiness zones 3-8.

Mertensia oblongifolia (Oblongleaf Bluebells, Sagebrush Bluebells)
This species is native to the western United States and prefers to grow in meadows and sagebrush. Leaves are lance-shaped and green, and flowers are purple-blue, opening from pink buds. The maximum height of these plants when in flower is 16 inches tall. This species is suited for USDA hardiness zones 3-8.

Mertensia paniculata (Tall Lungwort, Tall Bluebells, Northern Bluebells, Panicled Bluebells)
These herbs or dwarf shrubs produce drooping bright blue, bell-shaped flowers and is native to northwestern North America and the Great Lakes region. Plants form rhizomatous roots, which they rebloom from after harsh weather events. They flower between May and September in their native range. Tall Lungwort is suited for growing in USDA hardiness zones 3-9.

Mertensia sibiricia (Japanese Bluebells, Siberian Bluebells)
This species is native to Siberia and northern China. It forms a nectar-producing plant with blue-green foliage. Abundant flowers are bluish and bell-shaped. These plants are considered rare, and prefer to grow on grassy hillsides. Japanese Bluebell plants grow well in USDA hardiness zones 3-9.

Mertensia virginica (Pulmonaria virginica) (Mertensia pulmonarioides) (Virginia Bluebells, Virginia Cowslip, Lungwort Oysterleaf, Roanoke Bells, Blue and Pink Ladies, Smooth Lungwort, Virginia Spiderwort)
Best in USDA hardiness zones 3-9 or Sunset growing zones 1-9 and 14-21, this species is native to the eastern United States and produces a plant 1-2 feet tall and 1.5 feet wide. This is the most widely grown species of Mertensia. Flowers are sky blue (though they can be pink to white).

Caring for Mertensia

Take care when planting these flowers in the landscape, as they are mildly toxic if ingested and have the potential to cause contact dermatitis in sensitive individuals. Mertensia plants should be grown spaced between 12 and 18 inches apart in partial to full shade. They typically grow in woodland environments, and appreciate dappled sunlight or bright indirect sunlight. If grown in some sun, make sure plants receive at the very least some afternoon shade when temperatures are at their peak. They appreciate a substrate that is well-draining, moderately fertile, and that has a pH of between 6.8 and 7.2 (slightly acidic to neutral). If local soils are particularly poor in nutrients or do not drain well, make sure to amend the planting area with plenty of organic compost before installing. After planting, lay down a thick layer of organic mulching material to help suppress weed growth, maintain consistent soil temperatures, and increase soil moisture retention.

Fertilize yearly in early springtime with an application of 2 inches of compost around the base of plants. Pull mulch back before applying, work the compost gently into the soil a bit, water it in, and then replace mulch. These plants are not heavy feeders, and this should be sufficient to provide the necessary nutrients for the active growing and flowering seasons. Foliage will die back in the middle of summer when temperatures and humidity rises. After foliage fades, cut it back to just above the soil level. Flowers can be deadheaded throughout the growing season to discourage the spread of seeds. If you will be harvesting plants for seeds, make sure to leave some of the flowering stems on a few plants to be harvested later on. Mertensia spreads slowly via underground rhizome roots, and needs to be divided every few years if grown in a space-limited situation, such as in a raised bed or container. For instructions on how to successfully divide Mertensia, see the Propagation section below. These plants are considered herbaceous perennials and can survive in the landscape for 3 to 5 or more years before needing to be replaced. They will produce offsets that can be propagated indefinitely for new landscape plants.

Propagation

Mertensia, or Bluebells, can be propagated either by division or from seed. To ensure that your propagated plant will have the exact same qualities and characteristics as the parent plant, use the division method. If you would like to experiment and see what plant you can grow from seed, just keep in mind that it will not necessarily be the same as the parent plant. To propagate your Bluebells, follow the instructions below:

Propagating Mertensia by Seed

Keep in mind that the plant you get from seed will not necessarily mimic all of the characteristics of the parent plant. To propagate by seed, you will need a paper bag, a pot or tray filled with well-draining compost or other organic material, a spray bottle and a fork. The best potting medium for seed germination is a light blend of 1/3 pasteurized soil or compost, 1/3 sand, vermiculite or perlite, and 1/3 coconut coir or peat moss.
Harvest your seeds. The seed heads on plants are pretty easy to spot, they're left behind after flowers have faded. Once they have dried out and begun to split open, you can harvest the seeds inside. Cut them off of the plant, placing them in a paper bag. Harvest as many as you can, and place the paper bag in a dry, cool, dark area. They will continue to split open and release the seeds contained inside. Once they have been released, take them out of the bag and put them in a container so you can work with them.
For seeds to germinate, they will need to undergo a process called 'cold-stratification', which mimics the conditions in their native environments. To complete this treatment, place seeds in a sealable bag or other container filled with moistened sand or peat moss, and then place that container in the refrigerator or a similarly cool environment. Leave the container there for between 4 and 6 weeks, and then remove seeds and get ready to sow them.
In either late winter or early springtime, get your container prepared. Water your prepared seed tray or pot filled with soil, and ensure that good drainage is occurring. Place your seeds in your prepared pot or seed tray about a quarter inch to a half-inch under the soil surface. Cover them with soil and water with your spray bottle. Place your tray of seeds in a warm area that receives bright, indirect light. A greenhouse is the most ideal climate, but a planting tray inside a window will do as well. Germination usually takes 2-6 weeks from sowing. Once you begin to see seedlings sprout and they are able to be handled, transplant them to their own individual 3-inch pots, filled with the same potting medium as described in Step 1. Loosen the seedlings from the potting medium by digging down with the tines of your fork about an inch and a half, gently working the seedling up until it is out. Then, replant the seedling in its individual pot.
Keep the seedling's potting medium moist, but not wet, by spraying the soil with your spray bottle. Keep your new plant in an area with bright light (though not direct sunlight) and temperatures between 65 and 72 degrees Fahrenheit. Ensure that the soil stays moist, but not wet, until the next spring (after the danger of frost has passed), when you can transplant it to its new home.

Propagating Mertensia by Division
This type of propagation is relatively simple; you will need a clean shovel, mulch, fresh soil, compost and pots (only necessary if you will be saving divided plants for transporting elsewhere). Division is best done in very early spring (after the plant has entered dormancy, but before it has begun its new spring growth), and needs to be done every few years regardless of whether you have the goal of propagating the plants for best performance. To propagate by division, follow these steps:

Using a shovel, dig up your existing plant. Start from the outside and work your way in to avoid damaging the root(s). Once you have worked it up out of the ground, lay it out.
Start to tease apart the roots with your fingers. Once the roots are untangled, separate your plant into segments, ensuring that each one has at least one thick root section attached.
Prepare your pot(s) or new planting site(s) with amended, well-draining soil. You can either bring in new soil or simply amend your existing soil with compost to complete this task. Then, plant your divisions and water thoroughly.
Apply a thick layer of mulch over the new planting to protect it from cold weather as it acclimates to its new home. Then, enjoy watching it sprout in the next growing season.

Mertensia seed pods will dry out and turn brown when seeds are mature.

Mertensia seeds are typically dark brown to almost black in color and are pointed towards one end.

Problems and Pests

Mertensia plants are typically quite resilient in landscapes, though they can suffer from issues with the following pests and diseases from time to time: