Lungwort is best planted in late summer to fall from potted nursery plants, though spring planting is also generally successful. It has a moderate growth rate and the rhizomatous roots will spread gradually to colonize a shady area. Overall, caring for these plants is fairly straightforward. Make sure they have adequate water and shade, and feed them annually.
Light
Lungwort is typically grown in partial sun to full shade. But it can tolerate quite a bit of bright light in the early spring, which is helpful because not as many trees have leafed out at that point to diffuse sunlight hitting the lungwort. Harsh direct sun in hot weather can wilt the plant and scorch its leaves. But too much shade can minimize the plant’s blooms.
Soil
Lungwort plants prefer to grow in organically rich, humusy soil that remains moist. Dry soil can cause the plants to decline and go into dormancy, but soggy soil can encourage root rot. Lungwort is highly sensitive to soil pH, and the plants will perform poorly when soil pH strays outside the 7.0 to 8.0 range. The shift in flower color from pink to blue is because the plants pH levels shift as the growing season progresses. In one study, 7.5 was determined to be the ideal soil pH level.
Water
These plants need a moderate amount of moisture and struggle in soil that is too dry or too wet. Water whenever the soil begins to dry out due to a lack of rainfall and/or particularly hot weather. But don’t overwater to the point that the plant is sitting in soggy soil for a prolonged period.
Temperature and Humidity
Lungwort plants thrive in mild temperatures and tend to struggle in hot climates. They start growing as soon as the danger of frost has passed in the spring. Hot summer weather might cause them to wilt; however, they should perk up again once the cooler temperatures of fall arrive.
Fertilizer
Lungworts don’t require frequent or heavy fertilization, which can actually reduce flowering. In the early spring, sprinkle a small amount of all-purpose garden fertilizer around the plant. Mixing compost into the soil also can help to promote healthy growth.
Types of Lungwort
Most lungwort varieties sold for garden use are cultivars of hybrids created by cross-breeding key species, especially P. saccharata, P. angustifolia[, and P. longifolia. The exact parentage is often unclear, and these cultivars are often simply labeled Pulmonaria. New cultivars appear regularly, but some current favorites include:
‘Blue Ensign’:This is a very early bloomer with cobalt-blue flowers and solid dark green leaves. ‘Raspberry Splash’: This variety shows dramatic clusters of raspberry pink, and soft lavender flowers, with dark green leaves speckled with silver. ‘Shrimps on the Barbie’: This variety has pink flowers and long green leaves speckled with silver. ‘Trevi Fountain’: This version has unusually large cobalt flowers and longish medium-green leaves with silver spots. ‘Majeste’: This cultivar has pinkish flowers that gradually turn blue-violet. The leaves are long and lance-shaped, silver-gray with green margins. ‘Excalibur’: A clump former with silver leaves and long-lasting violet-blue flowers. ‘Spilled Milk’: This hybrid has the familiar pink-transitioning-to-blue flowers. Young leaves are tinged purple, changing to white as they age. ‘Roy Davidson’: This plant has dark green leaves with silver-white spots; the flowers are pale blue. ‘Smokey Blue’: This plant has silvery spotted foliage with pink flowers that turn blue. Pulmonaria officinalis ‘Sissinghurst White’: This plant has long, speckled leaves with pale pink buds that open to pure white blooms.
Pruning
Remove flower stems as they finish blooming. After lungwort is finished flowering, the flower stalks turn brown and flop over, and the older leaves also begin to look tattered. Removing the entire flower stalk and the degraded leaves will encourage the plant to rejuvenate with fresh growth. You also can prune off leaves that degrade from especially hot or dry weather, as needed. Some gardeners choose to simply mow off the tops of the plants as they go dormant during the dry hot, mid-summer period. If kept well-watered, the plants will rejuvenate as the weather cools.
Propagating Lungwort
Because most modern Pulmonaria varieties are hybrids, they are not generally propagated from seeds collected from the plants. Seeds produced by hybrids usually do not “come true” to the parent plant. Instead, propagation is best accomplished by root division. Here’s how to do it:
How to Grow Lungwort from Seed
Because most garden varieties of lungwort are hybrids, plants started from collected seeds generally do not “come true” to the parent plant. Thus, propagating by seed is not usually recommended. The plants will readily self-seed, and while it is possible to transplant the volunteers into new locations, it is typical for these offspring plants to have much different color than the parent plants.
Potting and Repotting Lungwort
It is theoretically possible to grow lungwort in containers filled with potting mix, but in practice it is not often done, as the plants will require a lot of maintenance. Lungwort plants will require frequent water, and because most potting mixes are peat-based and therefore naturally acidic, you will likely need to amend the potting mix with agricultural lime to raise the pH. Overall, container culture for lungwort is not worth the trouble, as the plants will not perform nearly as well as when they are grown in a good moist, shady garden location.
Common Pests & Plant Diseases
Lungworts don’t have any notable pest or disease problems. But they can be prone to powdery mildew, and slug damage, which results in abnormal and damaged foliage. Powdery mildew is not generally fatal, but it can be treated with spray fungicide.
Overwintering
Lungwort is best covered with mulch after the ground freezes in the winter. This will moderate freeze-thaw cycles and ensure that roots survive the winter. This is especially necessary in zones 3 and 4, where winters can be quite bitter with rapid cycles between temperature extremes.
How to Get Lungwort to Bloom
Though often grown primarily for its foliage, the flowers on lungwort can be quite attractive. Good flowering is dependent on just the right conditions: some sun in the morning but shade in the afternoon; consistently moist but not soggy soil; a soil pH that remains in a narrow range from neutral to slightly alkaline; minimal fertilizing. Getting good blooms is usually a matter of adjusting these variables to give these plants the conditions they prefer.
Common Problems With Lungwort
Lungwort needs fairly precise conditions to flourish, but if those are provided, they are easy to grow and will give you few problems. However, gardeners who are new to this plant are sometimes troubled by the way they die back when the weather turns hot and dry in midsummer. But this is fairly natural with this plant and not a cause for concern. Cutting back the plants and keeping them moist (but not soggy) usually encourages them to return as hot summer weather begins to cool in the fall.
