Mature size & growth rate

How big does Lungwort 'Mrs Moon' (Pulmonaria saccharata) get?

Also called Mrs Moon Lungwort, Bethlehem Sage, Jerusalem Cowslip.

More about lungwort 'mrs moon'

About Lungwort 'Mrs Moon'

Pulmonaria saccharata · also called Mrs Moon Lungwort, Bethlehem Sage · flowering

Lungwort 'Mrs Moon' is a classic spring-flowering shade perennial with heavily silver-spotted, semi-evergreen leaves and funnel-shaped flowers that open pink and age to blue-violet. An excellent ground cover for shaded and woodland borders. Prefers moist, humus-rich soil. Pet-safe according to ASPCA.

Mature size: 25-35 cm tall; 40-60 cm wide

Watch for — Powdery mildew: The most common problem, especially in dry or warm summers; cut back affected foliage hard after flowering and water well to encourage fresh growth.

Indoor size vs how big it gets in the wild

Lungwort 'Mrs Moon' stays fairly low but widens over time — it spreads into a bigger clump by offsets, runners or rhizomes rather than shooting upward. Indoors and in a pot, expect 25-35 cm tall. In the ground with no restriction it is a completely different plant — 40-60 cm wide — which is why the pot, the light and the pruning matter so much for the size you actually end up with.

Size here is about width, not height: the plant builds an ever-wider clump or sends out plantlets and runners while staying relatively short.

Growth rate and years to mature

Lungwort 'Mrs Moon' is a moderate grower. Realistically, expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Its feeding profile backs this up: a spring top-dressing of balanced fertiliser or well-rotted compost is usually sufficient. pulmonaria is not a heavy feeder; avoid nitrogen-rich feeds that promote soft, disease-prone growth at the expense of the distinctive spotted foliage.

Want this turned into the right next pot at the right moment? The pot size calculator and the lungwort 'mrs moon' repotting guide cover when and how much to size up — pot size is one of the biggest levers on how fast lungwort 'mrs moon' grows.

How to keep lungwort 'mrs moon' smaller

You are not stuck with the maximum size. For lungwort 'mrs moon' specifically, these are the levers, in order of impact:

Divide the clump every year or two — splitting lungwort 'mrs moon' is the main way to control its spread and refresh it.
Remove runners, plantlets or offsets as they appear if you want it to stay a single tight clump.
Keep it slightly pot-bound; a snug pot naturally limits how wide the clump can get.

The keep-it-smaller method, step by step

Lift the whole plant. Slide lungwort 'mrs moon' out of its pot in spring when the clump has filled it.
Split the clump. Tease or cut the rootball into two or more sections, each with healthy roots and growth.
Repot one division. Put a single division back in the original pot to reset it to a smaller size; pot or give away the rest.
Remove offsets as they form. Through the year, detach new runners or pups to stop it spreading again.

How to grow lungwort 'mrs moon' bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for lungwort 'mrs moon' the accelerators are:

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger.
Brighter light speeds up clump and offset production noticeably.
Leave plantlets and offsets attached and feed through the growing season for the fastest spread.

Light is almost always the ceiling. The lungwort 'mrs moon' light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When lungwort 'mrs moon' outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for lungwort 'mrs moon':

The clump bulging over the pot rim or splitting the pot — the cue to divide, not to find a bigger room.
A dense centre that goes bare or tired while the edges keep spreading.
Runners or offsets escaping across the shelf or into neighbouring pots.

If it is the pot rather than the room, it is a repotting job, not a goodbye — see the lungwort 'mrs moon' repotting guide. If you want more of this plant instead of a bigger one, the lungwort 'mrs moon' propagation guide turns prunings into new plants.

Lungwort 'Mrs Moon' size — frequently asked questions

How big does lungwort 'mrs moon' get?

Lungwort 'Mrs Moon' reaches 25-35 cm tall when grown indoors, and far larger where it grows unrestricted (40-60 cm wide). Size here is about width, not height: the plant builds an ever-wider clump or sends out plantlets and runners while staying relatively short.

Is lungwort 'mrs moon' slow or fast growing?

Lungwort 'Mrs Moon' is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Lungwort 'Mrs Moon' stays fairly low but widens over time — it spreads into a bigger clump by offsets, runners or rhizomes rather than shooting upward.

How long does lungwort 'mrs moon' take to reach full size?

Roughly three to six years to reach mature indoor size, gaining a steady amount each growing season. Light, pot size and feeding move that timeline more than anything else.

How do I keep lungwort 'mrs moon' smaller?

Divide the clump every year or two — splitting lungwort 'mrs moon' is the main way to control its spread and refresh it. Remove runners, plantlets or offsets as they appear if you want it to stay a single tight clump. Keep it slightly pot-bound; a snug pot naturally limits how wide the clump can get.

How can I make lungwort 'mrs moon' grow bigger or faster?

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger. Brighter light speeds up clump and offset production noticeably. Leave plantlets and offsets attached and feed through the growing season for the fastest spread.