Ferns-believer: Vitro Plus is now offering hardy ferns

Dryopteris championii.

A relative newcomer to hardy fern breeding, propagation and marketing has been founded on a company’s three-decade expertise in tissue culture reproduction of tropical ferns in the Netherlands. Vitro Plus co-owner John Bijl chose to diversify into perennial ferns because of the plant’s unrivalled beauty and fantastic variety, pent-up consumer demand, the product’s compelling narrative, and a desire to explore new territory.

Life is full of surprises when you least expect it. John Bijl (aged 62), the son of a grower, grew up at the family nursery in Dordrecht. There were always many gardening chores, some more bearable and enjoyable than others. He reminisces, “The one job I particularly disliked was the cleaning and weeding of ferns. I vividly remember how I hated ferns because keeping them tidy and healthy was tedious, dirty, and time-consuming. Looking back in hindsight, it is rather surprising how gradually I developed a passion for these plants.”

The upcoming science of plant tissue culture

Bijl studied biology at a young age, fuelling his desire to learn more about ornamental plant propagation. He recalls, “After college, I did microbiological research and worked as a lab assistant in a hospital, test tubes being my familiar pieces of equipment. Meanwhile, a newfangled way of plant propagation emerged called tissue culture, and the tech and science part of it really struck my fancy. By then, I worked as a biology teacher and decided to combine this job with a tissue culture laboratory in orchids and ferns. We opted for tropical ferns first because of the product’s significant and stable ranking and a desire at the grower’s level to multiply by tissue culture to reduce labour costs and achieve more reliable and healthy plants.”

With Kees Zevenbergen as co-founder, Vitro Plus started as a side project. Bijl recalls how he started the business without any outside financing, working from his home in Dordrecht at his kitchen table, then later in a Portakabin.

One of Vitro Plus’s first customers was the family business, where he had worked as a youngster. Bijl says, “The company was reproducing their ferns by division of rhizomes but wanted to replace this technique by tissue culture. Apparently, they relied on my study background, bringing ferns over and asking me if I could multiply them by this new technique.”

Initially, the idea was to set up a tissue culture lab to mass propagate popular orchids and ferns. Bijl explains, “However, this part of the operations was divested because our work in orchids wasn’t good enough and turned out to be too labour-intensive. And no, shifting tissue culture production to developing countries, where labour is cheaper, was not an option as I always want to have a sense of control of my work.”

Vitro Plus’s co-owner John Bijl in the company’s newly built Hardy Fern lab in Burgh–Haamstede.

Roadmap to success

Despite his background in (micro) biology and, apart from being intellectually curious and interested in tech, things were not easy in the beginning. Little did Mr Bijl know about fern propagation through tissue culture. There was no textbook, and the scarce knowledge that existed was protected and not free to use.

While he candidly admits that a fledgling Vitro Plus in 1990 put little care and thought into crafting a business model, the firm’s roadmap to success is clearly paved with patented innovations and the introduction of new breeding breakthroughs. The strategy mostly boils down to doing things differently and better about fine-tuning operations and enhancing crop quality, yields, and sustainability. In the 2000s, for example, Vitro Plus was an early adaptor of LED lighting in multi-tier growth chambers for the propagation of tropical ferns.

Thirteen years later, LEDs allow Vitro Plus to maximise the company’s production while saving energy costs and culture space. Vitro Plus also owns a patent protecting its growing system, of which a Vitro Plus tray, plug, and permeable foil are integral parts. The system is used to grow tissue culture and spore-raised fern plantlets in a sterile environment, a pre-requisite for shipping starting material to the USA, known as the world’s biggest fern market (see side panel). It gives the business a competitive advantage over others.

Vitro Plus also created quite a stir when it introduced Nephrolepis exaltata ‘Nevada’, aka the Nevada Fern. Since its discovery, the fern has continued revolutionising the global market with its dark green and vigorous foliage and in-built drought resistance.

Bever Innovations’s Leaf Carrier LED panels look somewhat like giant LED TV screens.

Entering the hardy fern market

The news of the moment is that the company is entering the adjacent market for hardy ferns. In 2020, Vitro Plus completed a two-story building adjacent but separated from their existing tropical fern lab in the medieval town of Burgh Haamstede (providing the Fern King with 5,000m² additional lab space, offices, and a canteen). Today, Vitro Plus’s total growth space spans 10,000m² with an annual output of 50 million plantlets.

The new Burgh-Haamstede facility (75km south of Rotterdam) offers a fully conditioned growing environment without natural daylight.
The fern propagator ensures that the new business complex minimises the company’s environmental footprint; solar panels provide electricity for the LED lighting, smart cultivation techniques save water, and pesticides are unnecessary thanks to the closed-loop system. They are meeting the increasing demand for ferns worldwide.

The new building allows Vitro Plus to double its annual production to meet the increasing demand for (less common) hardy ferns worldwide.

Inside Vitro Plus’ Victorian greenhouse. Pictured are Microsorum musifolium ‘Crocodyllus’ (crocodile fern) and a tree fern called Cyathea cooperi.

A new fern craze in the making?

Commenting on the current state of the global fern market, Mr Bijl says, “Stable trade volumes have marked the past two decades. At the same time, we can see a significant change in consumer behaviour with a growing demand for unusual ferns. In the old days, Nephrolepis dominated the market, but currently, consumers are keenly interested in ferns that don’t look like ferns.”

It would be somewhat far-fetched to suggest that the world is seized by a new fern craze as seen in the Victorian era (1850-1890), but Bijl thinks that houseplants haven’t quite reached their popularity peak. A more eco-conscious consumer intends to keep spending on products that enhance their health and well-being. Some ferns, such as the tiny Azolla, can capture CO₂ and nitrogen from the air and are piggybacking on a global eco-trend.

Athyrium niponicum ‘Pictum’ detail.

Obtaining new varieties

There are several ways to obtain new varieties. Spontaneous genetic variation is one of the motors of fern evolution, with Vitro Plus’s earlier mentioned Nevada Fern or Phlebodium aureum ‘Davana’ – a blue star type fern that stands out for its ruffled, bluish-green foliage – being shining mutation examples.

A second method is plant exploration. For this, Vitro Plus collaborates with modern plant explorers who ‘hunt’ ferns in woods, among rocks, in mountain ranges and waterfalls worldwide. Ultimately, the goal is to find species with significant commercial potential. But this is a delicate exercise as conserving biodiversity and respecting the principles of the Nagoya Protocol is also at stake.

A third possibility is to undertake high-precision cross-fertilisation of spores in the laboratory. Bijl notes, “We are testing the waters, but it is still too early to announce outcomes of our fern breeding programme. We sell a few crossing varieties, but until now, they have been found by third parties. Generally speaking, opportunities to expand our hardy fern portfolio are plentiful and exciting.”

Polystichum polyblepharum

Spore propagation

Ten years ago, Bijl started to read the first stories about the Victorian fern craze that turned him into a fervent hardy fern proponent. He explains, “I realised how compelling the product’s narrative is, how nearly all layers of British society back then were bitten by the fern bug, collecting, growing, and exchanging varieties. Then, I asked myself, if there are so many intriguing stories about hardy ferns, why not propagate them and use storytelling and a consumer brand as powerful communication tools.”

Bijl acknowledges that propagating hardy ferns has a specific set of challenges. “Because of our in-depth experience gained in meristem culture for tropical ferns, we first tried to reproduce the hardy specimens through tissue culture. This model proved unprofitable as it comes with competition against cheaper spore-raised hardy ferns. Interestingly, some species, such as Athyrium niponicum, aka the Japanese painted fern, are unstable when multiplied through spores, so we have recourse to tissue culture. These niche-type varieties are higher priced, compensating for the more expensive tissue culture. Spores can be yellow, green, brown, or black. Matteuccia features green spores, which complicate propagation. So, also for these ferns, we use tissue culture.”

There has long been a certain mystery surrounding the spore reproduction of hardy ferns. Until the refinement of optical equipment in the mid-19th century, it was unknown how ferns developed.

Then, research unveiled all the unknowns about these ancient plants that inhabited the Earth long before the dinosaurs. Ferns do not flower, are seedless and reproduce sexually from spores.

There are two distinct stages of the fern life cycle: the diploid generation, consisting of sporophytes, thus spore-bearing plants, and the haploid generation, represented by tiny heart-shaped plantlets, aka the prothallia or gametophytes. These contain the sperm and egg. When conditions are damp enough, the sperm swims to the ovum and fertilises, eventually resulting in a new sporophyte or spore-bearing fern.
Bijl explains, “Vitro Plus’s greenhouses in Zierikzee host mother stock plant for harvesting spores. For that, we cut the fronds, dry them, clean them, and collect the spores, which sometimes need help to fall off.

“There are so many spores on one leaf that quantity is not a problem, but quality sure is. So, we thoroughly test the spore quality under the microscope and sow test best batches to decide the germination rate.”

Compared to tissue culture, spore propagation is complex but significantly less labour-intensive. The key to successful spore propagation lies in a clean (in-house) sterilised substrate to stay away from fungi and insect eggs. Sterilising the growing media is a delicate balancing act as it must not be 100 per cent sterile because then spores won’t germinate.

Bijl continues, “Depending on the variety, there are fewer or more spores per cocopeat plug, which sits in a Vitro Plus tray. Subsequently, trays are watered, sealed with permeable Vitro Plus foil and put into the growth chambers under LED lights.”

The transformation from a spore to a gametophyte and subsequently into a sporophyte happens in the same sealed and sterile trays, which only open upon arrival at customers in the USA and Australia. This unique cultivation method is patented and allows the company to export their fern starter plants worldwide. Vitro Plus customers abroad, read growers, transplant the sporelings manually or with the help of robotic transplanters. The company offers hardened off-quality liners for Dutch and European customers.

Bijl notes, “The time from spore to gametophyte takes between 10-16 weeks, and another 10-15 weeks to obtain a sporophyte plant. Effective communication with our customers is vital so that they understand we cannot eliminate steps in the cultivation process to trim lead times. Therefore, we encourage them to pre-order at least six months upfront.”

Vitro Plus’s Micha van der Burgwal doublechecks plantlets before they are hardened off in a greenhouse.

New types of customers

Venturing into the hardy fern market, Bijl says, also comes with a new type of customer. “Buyers of hardy fern starting material are mostly perennial plant growers; their nurseries have a different layout and also tend to have a different customer base, selling directly to garden retailers.

Plus, perennial plant growers grow a wide plant range with many varieties produced in smaller quantities. Plants are frequently higher-priced, and the knowledge level of hardy fern growers is quite high.”

As hardy ferns were relatively new to Vitro Plus, the company decided to put additional time into studying and testing the features and benefits of the portfolio, which currently consists of around 70 varieties, with a hundred more being a work in progress.

The company’s hardy ferns are also planted out in a purpose-built show garden that bears the same name as the firm’s new consumer brand for hardy ferns: Cedar House Ferns (see side panel). Bijl explains, “Here we learn how our varieties perform in nature. Also, we dived into the tech part of spore propagation, which completely differs from tissue culture. We chose to grow all hardy fern plantlets in a lab using what I always call ‘our magic box’, an absolute first in hardy fern propagation.”

Traditional in vivo young plant growers increasingly use Vitro Plus’s magical multilayer climate chambers as an example of plant propagation 2.0.

And this is not without a reason. Under the EU’s Farm to Fork and Green Deal strategies, and with mandatory Integrated Pest Management (IPM) anchored in EU legislation, starter plant professionals see their pesticide cabinets empty rapidly. Bijl explains, “By growing your plantlets under controlled and sterile laboratory conditions, you can reduce the application of crop protection chemicals. Tissue culture also allows year-round and high-density production, rapid and controlled plant growth.”

Despite the many meristem merits, there are several reasons why Vitro Plus prefers to stick to its ferns instead of developing into a full-service supplier for contract plant propagation. He elaborates, “Propagating different crops and gaining in-depth knowledge of each of these crops is perhaps impossibly difficult. In such a scenario, we would merely be the go-to place for tech. But such quick wins will not build a great product and a long-term sustainable business.

“At Vitro Plus, it is not only about tech, but our unique selling points also include plant breeding and propagation expertise, fern variety and product and marketing knowledge.

“We want to tick all the boxes so that our ferns help our customers succeed.”

Tropical ferns versus hardy ferns

Even in the Dutch winter garden, this Polystichum munitum (western sword fern) performs well and continues to be visually appealing.

The terms tropical ferns, with which Vitro Plus earned strong brand recognition over the past 33 years, and hardy ferns can be used interchangeably as the hardiness of ferns depends on their native extent’s geographic location, longitude, latitude, and elevation. Mr Bijl explains,
“What in Europe is known as a fern for indoors can be suitable for growing outdoors in Florida. Some ferns you grow outside are also suitable for indoors and the other way around, but not always. It is a complex matter, but we try to make it easy for people to understand.”
The world’s hardiness zones help people decide which ferns they should plant with the best chances of survival. Mr Bijl notes, “In the face of climate change, these climate zones are shifting. Fern hardiness also depends on the species’ natural habitat and the altitude at which they grow. Fern hunters also explore, for example, the Ethiopian highlands (where they found Asplenium aethiopicum) or the Himalaya Mountain range. There are billions of spores moving around the world, and basically, you can find fern species where you would never have expected them.”

 

Vitro Plus launches consumer website in conjunction with new fern brand

In conjunction with its new Cedar House Ferns brand, Vitro Plus announces the launch of a new website,
www.cedarhouseferns.com.

Many types of hardy ferns are also popular plants for the garden, but they have long played a kind of subdued role, often considered as a side crop at perennial plant nurseries and in garden retail.

Selling hardy ferns is not always easy. The deciduous types lose their leaves in winter, and empty-looking pots do not quickly fly off the garden centre shelves.

With this in mind, Vitro Plus launched Cedar House Ferns, a new B2C fern brand to help ferns rise in prominence.

The Cedar House Fern logo illustrates a Victorian-style greenhouse featuring wooden frames and ornate decorative elements. In real life, the greenhouse is surrounded by a spectacular woodland garden in Burgh Haamstede that will eventually host more than 300 different fern species. It also includes a log-style guesthouse not far from Vitro Plus headquarters. The garden and greenhouse are open to the public, but visitors must book their visit in advance.

The Cedar House Fern brand did not happen overnight. Mr Bijl explains, “For a few years, we have participated in castle flower, and plant shows such as Kalmthout, Trompenburg and Beervelde. Here, we showcased our perennial fern range to determine what consumers like most.”

The next step is a Cedar House Ferns display at Groenrijk’s garden centre in Middelburg next spring. The fern area promises to be very different from standard retail displays, including wooden timber frames, wooden plant labels, biodegradable pots, and lots of compelling storytelling. Mr Bijl asserts, “The area will create a real wow factor. We will explain how the Victorian Fern Craze fuelled the arrival of many fern species in the UK and Europe and how, in modern times, we hunt for ferns in the Himalayas or Africa. We also highlight the fern’s air and soil-purifying capabilities. Research has found that some ferns efficiently remove inorganic and organic contaminants from the environment. For example, in 1996, NASA research referenced Nephrolepis as an ideal air-purifying plant.

This article was first published in the January 2024 issue of FloraCulture International.