Mature size & growth rate

How big does Blechnum chilense (Blechnum chilense) get?

Also called Chilean Hard Fern, Palmilla.

More about blechnum chilense

About Blechnum chilense

Blechnum chilense · also called Chilean Hard Fern, Palmilla · flowering

Blechnum chilense, the Chilean hard fern, is a bold evergreen species from the temperate rainforests of Chile and Argentina. It produces large, leathery, ladder-like fronds and spreads by creeping rhizomes to form dramatic colonies. New fronds often flush bronze-red before maturing to deep green, giving an architectural, jungle-like effect in mild, moist shade gardens.

Mature size: 60-120 cm tall, spreading steadily by rhizome to 1 m or more wide over time.

Indoor size vs how big it gets in the wild

Blechnum chilense 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 60-120 cm tall, spreading steadily by rhizome to 1 m or more wide over time.. 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

Blechnum chilense 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: undemanding; an annual spring mulch of compost or leaf mould keeps it vigorous. container plants benefit from a monthly half-strength balanced liquid feed during the growing season.

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

How to keep blechnum chilense smaller

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

Trim the longest vines back to the length you want — blechnum chilense 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 blechnum chilense 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 blechnum chilense bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for blechnum chilense 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 blechnum chilense light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When blechnum chilense outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for blechnum chilense:

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 blechnum chilense repotting guide. If you want more of this plant instead of a bigger one, the blechnum chilense propagation guide turns prunings into new plants.

Blechnum chilense size — frequently asked questions

How big does blechnum chilense get?

Blechnum chilense reaches 60-120 cm tall, spreading steadily by rhizome to 1 m or more wide over time. 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 blechnum chilense slow or fast growing?

Blechnum chilense is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Blechnum chilense 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 blechnum chilense 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 blechnum chilense smaller?

Trim the longest vines back to the length you want — blechnum chilense 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 blechnum chilense 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.