When you ask do you cut back Pulmonaria, the answer is yes, at least twice each year for the best display. Your first cut comes after spring bloom fades, and your second hits worn summer leaves in July or August. A light fall tidy rounds out your routine for healthy spring regrowth.
I sheared a tired clump down to 2 inches (5 cm) last August during a hot dry spell. In my experience, fresh silver leaves popped up within ten days of the cut. By September the plant looked brand new with no sign of summer stress at all.
Cutting back lungwort works so well because of how the plant grows from its core. The whole clump pushes out from a tight basal crown right at soil level. There are no woody stems to worry about like with shrubs or roses. New leaves come from buds tucked into the crown tissue.
Hard shearing does no harm to this kind of plant since the energy stores sit safe in the crown. The plant treats a hard cut like a fresh start signal. New growth springs up faster than you might expect, often within a week or two during warm soil months.
Your first cut of the year happens right after spring flowers fade in late April or May. This step is called deadheading, and it cuts down on self-seeding. Snip the flower stalks at their base where they meet the leaves. Use clean sharp shears for the job to avoid crushed stems.
The second cut hits in mid to late summer when leaves look tired, dusty, or bug-chewed. This is the big shear that renews the whole clump for fall. Cut all the foliage down to 2 inches (5 cm) above the crown. Toss the trimmed leaves in your compost bin if they look healthy.
For pruning pulmonaria in summer, pick a cool overcast day or work in the early morning hours. Hot sun on freshly cut crowns can stress the plant during recovery. Water deep right after the cut to spark fast new growth. A gallon of water per clump works well in dry weather.
Iowa State Extension and Garden Design both back the multi-cut approach for healthy plants. The combo of spring deadheading, summer shear, and fall tidy gives the strongest display. Skip any of these steps and the plant still lives, but the look suffers by August.
Fall trimming lungwort is much lighter than the summer shear in scope. Remove any browned or decayed leaves before winter sets in. Leave healthy semi-evergreen foliage in place to help shield the crown from cold. A quick pass with hand pruners takes just five minutes per clump.
Deadheading pulmonaria is the easiest cut of the three to learn and master. Spot the spent flower stalks once petals drop and turn brown. Trace each stalk down to where it meets the leaves at the base. Snip it off there with sharp shears in one clean cut.
Tool care matters more than most gardeners think for plant health. Wipe your shear blades with rubbing alcohol before and after each clump. This step blocks the spread of leaf spot fungus from one plant to the next. A clean cut also heals faster than a ragged one.
Compost healthy clippings right back into your garden cycle for free fertilizer. Toss any diseased leaves in the trash instead, since compost piles do not always kill fungal spores. Burn or bag heavily infected foliage to keep your bed clean for next year.
When I first grew lungwort, I left old leaves in place all summer thinking I might hurt the plant by cutting. The clumps looked sad and crispy by August every year. After I learned to shear hard each midsummer, my plants stayed fresh and silver right through frost.
Water deep after every major cut to help your plant rebound fast. A 5-gallon bucket of water poured slow at the crown soaks the root zone well. Top with fresh mulch if any soil shows around the base. Your reward is a clump that looks like new within two weeks of every shear.
Read the full article: Pulmonaria Plant: Complete Grower's Guide
