A little potted History

You know I love those little pieces of gardening history! This one came about whilst I was pondering the origins of glasshouses!

The Wardian case.

At first glance, it was simply a wooden box with glass sides – a miniature greenhouse designed to keep plants alive on long sea voyages.

But this rather unassuming little invention completely changed the movement of plants around the world. And, rather wonderfully, it came about almost by accident.

It started with a moth cocoon

In 1829, British doctor and enthusiastic amateur naturalist Dr Nathaniel Bagshaw Ward placed a moth cocoon into a sealed glass bottle containing a little moist soil and some fern material.

The observant Ward then noticed moisture condensed on the inside of the glass, ran back down into the soil and was taken up again by the plants. Sunlight could still pass through the glass, so inside the bottle a tiny, self-contained growing environment developed.

And the plants thrived.

In fact, Ward found that plants could survive inside this enclosed environment for remarkably long periods without being watered. It was essentially an early terrarium.

Ward realised that this little discovery might solve a much bigger problem.

Before the Wardian case, moving plants was incredibly difficult

During the great age of plant exploration, botanists were collecting extraordinary plants from all over the world.

But getting a living plant home was another matter altogether.

Imagine spending months at sea with plants exposed to salt spray, wind and extremes of temperature - while fresh water was far too precious to be used freely on them.

Many simply didn't survive.

Ward's answer was quite simple.

He developed a glazed wooden case that could sit on the deck of a ship where the plants received sunlight, but remained protected from saltwater and much of the outside contamination.

Inside, water circulated through evaporation and condensation.

So the plants effectively carried their own little climate with them.

In 1833, Ward sent two of his cases from London all the way to Sydney.

Inside were ferns, mosses and grasses.

After that enormous sea journey, the plants arrived alive.

That was quite a breakthrough.

Suddenly there was a reliable way of moving living plants thousands of kilometres across the world.

The Wardian case became, quite literally, a travelling miniature greenhouse.

Now for the New Zealand connection.

This is the part I thought was particularly interesting for us.

In the early 1840s, botanist Joseph Dalton Hooker used Wardian cases during his exploratory travels.

Hooker would later become Director of the Royal Botanic Gardens, Kew, following his father, William Hooker.

And among the plants Joseph Hooker sent back to Britain were plants collected here in New Zealand.

The shipment arrived at Kew in March 1843 and included species such as Kauri, Rimu, Southern Beech, Mountain Daisies, and an extensive collection of endemic ferns and mosses.

Imagine, living New Zealand plants had travelled halfway around the world by sailing ship, protected inside these little wooden and glass boxes.

By 1847, Kew was using Wardian cases regularly, often carrying around 28 plants in a single case.

A little box with a very big legacy

The design was gradually improved.

Wooden battens helped protect the glass and secure the plants. Ventilation holes covered with perforated zinc were introduced, and feet were added to lift the cases away from the wet deck.

But the basic principle remained wonderfully simple:

soil + moisture + sunlight + protection = a tiny self-sustaining growing environment.

Wardian cases continued to be used by Kew for nearly a century.

Eventually, air travel made transporting plants much faster, while increasingly important plant quarantine regulations restricted the movement of living plant material to prevent pests and diseases travelling with them.

Kew's last recorded use of a Wardian case was in 1962, when ornamental plants were sent from Fiji to Britain.

Today, only 19 original shipping Wardian cases are known to survive worldwide, eight of them at Kew.

It’s one of those little bits of gardening history we don’t hear much about, but without the Wardian case, the movement of plants around the world would have been a very different story.

And Joseph Hooker is a name you may already know without realising it. If you've walked the Hooker Valley near Aoraki/Mount Cook, crossed the Hooker River or looked towards the Hooker Glacier, you're seeing his name written into the New Zealand landscape. Ironically, Hooker never actually visited those places himself, but his botanical work in New Zealand was considered important enough for his name to be given to them. So the next time you're in that part of the country, there's another little gardening connection to tuck away.

Anyway, there’s a little bit of garden history for you this week.