Mature size & growth rate

How big does Brazilian Tree Fern (Blechnum brasiliense) get?

Also called Brazilian Tree Fern, Brazil Tree Fern, Red-leaf Blechnum.

More about brazilian tree fern

About Brazilian Tree Fern

Blechnum brasiliense · also called Brazilian Tree Fern, Brazil Tree Fern · tropical

Blechnum brasiliense is a dramatic tree fern from South America that unfurls striking bronze-red new fronds that mature to deep green. It thrives in high humidity and consistently moist soil, making it ideal for warm conservatories or sheltered tropical gardens. Avoid direct sun and cold draughts to keep fronds lush.

Mature size: Up to 90 cm tall and 90 cm wide in containers; up to 150 cm tall in warm outdoor conditions

Indoor size vs how big it gets in the wild

Brazilian Tree Fern is a tree at heart. Indoors a pot and your ceiling keep it to up to 90 cm tall and 90 cm wide in containers, but in the ground it is a different scale of plant entirely (up to 150 cm tall in warm outdoor conditions). Indoors and in a pot, expect up to 90 cm tall and 90 cm wide in containers. In the ground with no restriction it is a completely different plant — up to 150 cm tall in warm outdoor conditions — which is why the pot, the light and the pruning matter so much for the size you actually end up with.

It gains real height on a trunk or main stem, adding a tier of leaves a year and eventually reaching for the ceiling — this is a plant you grow up, not out.

Growth rate and years to mature

Brazilian Tree Fern is a slow grower. Realistically, expect a decade or more — slow growers like this add only a few centimetres a year, so expect 8-15+ years to reach their indoor ceiling. Its feeding profile backs this up: feed monthly with a balanced liquid fertiliser diluted to half strength during the growing season (spring through early autumn). avoid high-phosphorus formulas; excess fertiliser salts burn sensitive fern roots. do not feed in winter.

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

How to keep brazilian tree fern smaller

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

The decisive tool is the secateurs: brazilian tree fern can be topped (cut the main growing tip) to cap its height and force a bushier, shorter shape.
Keeping it deliberately pot-bound in a snug container slows the whole plant and limits ultimate size.
Prune in spring so it heals fast; remove the tallest leader back to a node to reset the height.
Good news: slow growth means topping it once buys you years before it needs doing again.

The keep-it-smaller method, step by step

Pick the new height. Decide how tall you want brazilian tree fern and find a leaf node or branch point just below that.
Top the main stem. Cut the main growing tip cleanly just above that node in spring; this permanently caps the height and forces side branches.
Keep the pot snug. Avoid jumping to a much bigger pot — a slightly restricted rootball keeps the whole plant smaller.
Maintain the shape. Prune back the tallest new leaders each spring to hold it at the height you chose.

How to grow brazilian tree fern bigger or faster

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

The biggest lever is light — a tree-type plant in dim light barely gains height; move it brighter.
Pot up a size every year or two while young; restricted roots are the main thing holding height back.
Feed regularly through the growing season and keep it warm — height comes from sustained good conditions.

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

When brazilian tree fern outgrows the room (or the pot)

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

The top leaves pressing against or bent by the ceiling — the classic "this is now too tall indoors" sign.
It has to be moved away from a light source it has literally outgrown.
Roots filling the largest pot you can reasonably keep indoors — at that point it is top-or-prune or move it outside (if hardy).

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

Brazilian Tree Fern size — frequently asked questions

How big does brazilian tree fern get?

Brazilian Tree Fern reaches up to 90 cm tall and 90 cm wide in containers when grown indoors, and far larger where it grows unrestricted (up to 150 cm tall in warm outdoor conditions). It gains real height on a trunk or main stem, adding a tier of leaves a year and eventually reaching for the ceiling — this is a plant you grow up, not out.

Is brazilian tree fern slow or fast growing?

Brazilian Tree Fern is a slow grower. Expect a decade or more — slow growers like this add only a few centimetres a year, so expect 8-15+ years to reach their indoor ceiling. Brazilian Tree Fern is a tree at heart. Indoors a pot and your ceiling keep it to up to 90 cm tall and 90 cm wide in containers, but in the ground it is a different scale of plant entirely (up to 150 cm tall in warm outdoor conditions).

How long does brazilian tree fern take to reach full size?

Roughly a decade or more — slow growers like this add only a few centimetres a year, so expect 8-15+ years to reach their indoor ceiling. Light, pot size and feeding move that timeline more than anything else.

How do I keep brazilian tree fern smaller?

The decisive tool is the secateurs: brazilian tree fern can be topped (cut the main growing tip) to cap its height and force a bushier, shorter shape. Keeping it deliberately pot-bound in a snug container slows the whole plant and limits ultimate size. Prune in spring so it heals fast; remove the tallest leader back to a node to reset the height. Good news: slow growth means topping it once buys you years before it needs doing again.

How can I make brazilian tree fern grow bigger or faster?

The biggest lever is light — a tree-type plant in dim light barely gains height; move it brighter. Pot up a size every year or two while young; restricted roots are the main thing holding height back. Feed regularly through the growing season and keep it warm — height comes from sustained good conditions.