Mature size & growth rate

How big does Hammock Fern (Blechnum occidentale) get?

Also called Hammock Fern, Tropical Hard Fern, Western Blechnum.

More about hammock fern

About Hammock Fern

Blechnum occidentale · also called Hammock Fern, Tropical Hard Fern · houseplant

Blechnum occidentale is a vigorous, terrestrial fern native to tropical and subtropical Americas, commonly found in humid hammocks and shaded forest floors. Its ladder-like, once-pinnate fronds emerge with a reddish-bronze flush and mature to glossy dark green. It is tough, fast-growing, and tolerates lower light better than many ferns.

Mature size: 40–70 cm tall, 50–80 cm wide

Indoor size vs how big it gets in the wild

Hammock 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 40–70 cm tall, 50–80 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.

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

Hammock Fern is a fast grower. Realistically, expect one to three growing seasons — fast vines can add a metre or more of stem in a single good summer. Its feeding profile backs this up: feed with a balanced liquid fertiliser at half strength every 4 weeks throughout the growing season (spring to early autumn). excess feeding is more harmful than under-feeding; high salt concentrations cause frond tip necrosis. skip feeding entirely in winter.

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

How to keep hammock fern smaller

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

Trim the longest vines back to the length you want — hammock 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.
Expect to tidy it every few weeks in summer — this is a fast vine that will sprawl if left.

The keep-it-smaller method, step by step

Decide the length you want. Pick the point each vine of hammock 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 hammock fern bigger or faster

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

When hammock fern outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for hammock 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 hammock fern repotting guide. If you want more of this plant instead of a bigger one, the hammock fern propagation guide turns prunings into new plants.

Hammock Fern size — frequently asked questions

How big does hammock fern get?

Hammock Fern reaches 40–70 cm tall, 50–80 cm 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 hammock fern slow or fast growing?

Hammock Fern is a fast grower. Expect one to three growing seasons — fast vines can add a metre or more of stem in a single good summer. Hammock 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 hammock fern take to reach full size?

Roughly one to three growing seasons — fast vines can add a metre or more of stem in a single good summer. Light, pot size and feeding move that timeline more than anything else.

How do I keep hammock fern smaller?

Trim the longest vines back to the length you want — hammock 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. Expect to tidy it every few weeks in summer — this is a fast vine that will sprawl if left.

How can I make hammock 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.