What 40 Years has Taught us about the Dicksonia antarctica Growth Cycle

Ruth van den Berg
Jun 15
3 min read

Four Decades of Watching Tree Ferns Grow

After more than 40 years working with Dicksonia antarctica, one thing has become very clear: not all tree ferns grow the same way.

Rows of healthy Dicksonia antarctica growing under controlled netted enclosures at Fernmania, demonstrating ideal conditions for rapid tree fern growth.

We've seen these remarkable plants growing deep in Tasmania's rainforests, rescued them from approved forestry operations, relocated them to new environments, and cultivated thousands of them under carefully managed conditions at Fernmania.

What we've observed over the decades is that environment appears to have a significant influence on how a tree fern develops, not just how quickly it grows, but how its trunk forms and matures over time.

Dicksonia antarctica in the Wild

In Tasmania's native forests, Dicksonia antarctica often grows beneath a dense canopy where light levels are lower and conditions can vary throughout the year.

Many of the mature specimens we encounter in the wild have incredibly dense trunks, often with tightly packed fern stem scars and a heavily compacted appearance. Some of the largest specimens we have rescued have exceeded one metre in trunk diameter, demonstrating just how substantial these plants can become over long periods of time.

These rainforest giants often give the impression of extremely slow, steady growth over many decades.

Controlled Growing Conditions Tell a Different Story

At Fernmania, we maintain more than 25 netted growing enclosures, the majority dedicated only to Dicksonia antarctica.

When provided with consistent moisture, protection from harsh conditions, suitable light levels and reduced competition from surrounding vegetation, we have observed that tree ferns can grow surprisingly quickly.

One of the most interesting differences appears in the trunk itself.

Ferns that have experienced rapid growth often display more elongated diamond-shaped leaf scars and a richer brown trunk colour. By comparison, older rainforest specimens frequently show more compressed and tightly packed trunk structures.

While every plant is different, our long-term observations suggest that tree ferns grown under ideal conditions may prioritise upward growth, resulting in a taller, more slender trunk compared to specimens that have spent decades growing slowly in the wild.

The Young Seedling Effect

One way we often describe it is that rapidly growing tree ferns seem to retain some of the characteristics of a young seedling.

A seedling's primary objective is simple: grow.

Under ideal conditions, mature Dicksonia antarctica can appear to continue that same growth strategy, putting energy into producing height and new fronds at a faster rate than we typically observe in natural rainforest conditions.

This is one of the reasons why cultivated tree ferns can sometimes look noticeably different from ancient wild specimens, even when they are healthy and thriving.

It's Okay to Be Alarmed, But It's Also Important to Be Informed

From time to time, people see a significant sized Dicksonia antarctica and assume that it has been around for decades.

Our experience suggests otherwise.

Different growing conditions often produce different growth characteristics. A tree fern growing in a carefully managed environment with abundant moisture and ideal conditions may naturally develop differently from one growing slowly beneath a rainforest canopy.

Neither is necessarily better or worse. They are simply responding to the environments in which they have spent their lives.