Mature size & growth rate

How big does Wall-rue Spleenwort (Asplenium ruta-muraria) get?

Also called Wall-rue Spleenwort, Wall Rue, Wall-rue.

More about wall-rue spleenwort

About Wall-rue Spleenwort

Asplenium ruta-muraria · also called Wall-rue Spleenwort, Wall Rue · houseplant

Asplenium ruta-muraria is a diminutive, evergreen, slow-growing fern native throughout the British Isles, Europe, Asia, and parts of North America, where it colonises the mortar joints of old limestone walls and natural rock crevices. Its tiny, branched fronds — resembling the herb rue in outline — grow to just 4–17 cm and form tight tufts in alkaline, well-drained conditions that would defeat most ferns. The single most important care note is that it requires an alkaline substrate and excellent drainage; it will quickly decline in acidic, waterlogged soil. It is generally considered non-toxic to pets, though it is not individually listed by ASPCA.

Mature size: Up to 10 cm tall and 20 cm wide.

Indoor size vs how big it gets in the wild

Wall-rue Spleenwort is a naturally small plant — it stays shelf- and desk-sized for its whole life, so it never becomes a space problem. Indoors and in a pot, expect up to 10 cm tall and 20 cm wide.. A pot, your light levels and a little pruning are what set the final size in a home, far more than the plant's theoretical potential.

It grows mostly by adding leaves, offsets or a slightly wider rosette rather than gaining height — the footprint barely changes year to year.

Growth rate and years to mature

Wall-rue Spleenwort is a slow grower. Realistically, expect many years — it gains very little each season, so it can hold the same shelf-sized footprint for 5-10+ years. Its feeding profile backs this up: no regular fertilising needed; excess nutrients produce lush, atypical growth that is more susceptible to pests and disease in this naturally lean-soil species.

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

How to keep wall-rue spleenwort smaller

Good news — wall-rue spleenwort barely needs managing. If you do want to keep it tidy:

You rarely need to do anything: wall-rue spleenwort is so slow that it can sit in the same small pot for years.
Keeping it slightly pot-bound and easing back on feed naturally caps the size.
Pinch or remove the oldest, tiredest leaves so energy goes into a compact, fresh-looking plant.

How to grow wall-rue spleenwort bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for wall-rue spleenwort the accelerators are:

Move it to brighter (but not scorching) light — that is the single biggest growth lever for a small plant.
A small step up in pot size every couple of years gives the roots a little more room without triggering a size jump.
Feed lightly through the growing season; this plant simply will not race however hard you push it.

Light is almost always the ceiling. The wall-rue spleenwort light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When wall-rue spleenwort outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for wall-rue spleenwort:

Roots circling the bottom or pushing out of the drainage hole — it wants a pot one size up, not a bigger room.
Offsets crowding the surface so the original plant looks squashed.
Honestly, wall-rue spleenwort rarely outgrows a room — outgrowing its pot is the only realistic limit.

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

Wall-rue Spleenwort size — frequently asked questions

How big does wall-rue spleenwort get?

Wall-rue Spleenwort reaches up to 10 cm tall and 20 cm wide. when grown indoors. It grows mostly by adding leaves, offsets or a slightly wider rosette rather than gaining height — the footprint barely changes year to year.

Is wall-rue spleenwort slow or fast growing?

Wall-rue Spleenwort is a slow grower. Expect many years — it gains very little each season, so it can hold the same shelf-sized footprint for 5-10+ years. Wall-rue Spleenwort is a naturally small plant — it stays shelf- and desk-sized for its whole life, so it never becomes a space problem.

How long does wall-rue spleenwort take to reach full size?

Roughly many years — it gains very little each season, so it can hold the same shelf-sized footprint for 5-10+ years. Light, pot size and feeding move that timeline more than anything else.

How do I keep wall-rue spleenwort smaller?

You rarely need to do anything: wall-rue spleenwort is so slow that it can sit in the same small pot for years. Keeping it slightly pot-bound and easing back on feed naturally caps the size. Pinch or remove the oldest, tiredest leaves so energy goes into a compact, fresh-looking plant.

How can I make wall-rue spleenwort grow bigger or faster?

Move it to brighter (but not scorching) light — that is the single biggest growth lever for a small plant. A small step up in pot size every couple of years gives the roots a little more room without triggering a size jump. Feed lightly through the growing season; this plant simply will not race however hard you push it.