Mature size & growth rate

How big does Peacock fern (Selaginella uncinata) get?

Also called peacock spikemoss, blue spikemoss, rainbow moss, spring blue spikemoss.

More about peacock fern

About Peacock fern

Selaginella uncinata · also called peacock spikemoss, blue spikemoss · houseplant

Peacock fern is a low, creeping spikemoss from southern China grown for its iridescent blue-green foliage — not a true fern. It demands constant moisture, high humidity and shade, so it thrives in terrariums. ASPCA lists its close relative Selaginella kraussiana as non-toxic, so it is treated as pet-safe; confirm with your vet.

Mature size: Around 8-15 cm (3-6 in) tall, spreading 30-45 cm (12-18 in) wide

Watch for — Leggy, sparse, thinning growth: Light too dim even for a shade plant, or humidity too low to support dense growth.

Indoor size vs how big it gets in the wild

Peacock fern does not get tall — it gets long. Size here is about stem length and how you train or cut it, not how much floor it claims. Indoors and in a pot, expect around 8-15 cm (3-6 in) tall, spreading 30-45 cm (12-18 in) 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.

Growth shows up as lengthening stems that trail down or climb up a support; the plant can be kept tiny or grown metres long from the exact same root system.

Growth rate and years to mature

Peacock fern 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: light feeder: a balanced liquid houseplant fertiliser diluted to quarter- or half-strength, applied monthly during spring and summer growth. skip feeding in autumn and winter, and avoid full-strength doses — excess fertiliser scorches the fine foliage.

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

How to keep peacock fern smaller

You are not stuck with the maximum size. For peacock fern specifically, these are the levers, in order of impact:

Trim the longest vines back to the length you want — peacock fern takes hard cutting well and bushes out from the cut.
Cut just above a leaf node; each trimmed stem usually branches into two, so pruning makes it fuller, not sparser.
The cuttings root easily in water or mix, so "keeping it smaller" doubles as free new plants.
A trim once or twice a season is usually enough to hold its length.

The keep-it-smaller method, step by step

Decide the length you want. Pick the point each vine of peacock fern should stop — you can be aggressive; it regrows readily.
Cut just above a node. Snip about 0.5 cm above a leaf node so the stem branches there instead of dying back.
Root the cuttings. Drop the trimmed pieces in water or mix — they root in 2-4 weeks and can fill the same pot for a bushier look.
Repeat as it runs. Re-trim whenever it overshoots; regular light pruning keeps it both smaller and fuller.

How to grow peacock fern bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for peacock fern the accelerators are:

More (indirect) light dramatically lengthens the vines and enlarges the leaves.
Give it something to climb — many vines grow far faster and bigger up a support than trailing.
Feed through spring and summer and keep it consistently watered while it is actively running.

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

When peacock fern outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for peacock fern:

Vines pooling on the floor or wrapping past where you want them — purely a trimming cue, not a repot one.
Bare, leggy stems with leaves only at the tips (usually a light problem, not a size one).
A tangled mass that has outrun its support and needs cutting back and re-training.

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

Peacock fern size — frequently asked questions

How big does peacock fern get?

Peacock fern reaches around 8-15 cm (3-6 in) tall, spreading 30-45 cm (12-18 in) wide when grown indoors. Growth shows up as lengthening stems that trail down or climb up a support; the plant can be kept tiny or grown metres long from the exact same root system.

Is peacock fern slow or fast growing?

Peacock fern is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Peacock fern does not get tall — it gets long. Size here is about stem length and how you train or cut it, not how much floor it claims.

How long does peacock fern 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 peacock fern smaller?

Trim the longest vines back to the length you want — peacock fern takes hard cutting well and bushes out from the cut. Cut just above a leaf node; each trimmed stem usually branches into two, so pruning makes it fuller, not sparser. The cuttings root easily in water or mix, so "keeping it smaller" doubles as free new plants. A trim once or twice a season is usually enough to hold its length.

How can I make peacock fern grow bigger or faster?

More (indirect) light dramatically lengthens the vines and enlarges the leaves. Give it something to climb — many vines grow far faster and bigger up a support than trailing. Feed through spring and summer and keep it consistently watered while it is actively running.