When a passionate orchid grower discovers fern tree fibre

Selwyn Hatrick provides a summary of his findings while growing orchids in tree fern fibre: 

My first orchid was a green-flowered cymbidium that I bought from a local plant nursery over 40 years ago.  It never flowered for me again, so I decided to visit our local orchid society hoping that someone there could help me.  On arriving at their meeting, I saw on display an array of plants and flowers that I had never seen or imagined.  I was instantly hooked and forgot about my cymbidium.

Within weeks, I ordered and assembled a glasshouse and then started my collection of species (and a few hybrids) of diverse genera. Within a couple of years it dawned on me that a mixed genera collection was demanding, and in the meantime I started to acquire a taste for paphiopedilums.  Over the following two years I quit most of the mixed genera collection and replaced them with species paphs. Not long after that I met Barry Fraser who was in the early stages of starting his paphiopedilum commercial nursery, Papa Aroha Orchids.

After viewing my orchids, Barry asked me if I would be prepared to makes some hybrid crosses for him, mainly of a type that was slightly off mainstream.  Many were made over the years following that visit. When Barry closed his nursery most of his breeding stock was sold to nurseries in the USA.  Fortunately I was able to acquire divisions of many of these before they were lost from our country.

I continue to breed with these in a small way. During the 1990 World Orchid Conference (Auckland, New Zealand) I attended a lecture that had a profound influence on my growing. The speaker showed a picture of some oncidium seedlings, some of which were deflasked into bark, and the others into a mix of bark and fern fibre.  They had been out of flask for about 3 months.  The difference was mind-boggling! 

Those growing in the fern fibre/ bark mix were about 30% larger. It was also stated during this talk that some other genera benefited greatly when potted in fern fibre, and paphiopedilums was one of these. Immediately following the conference, I phoned the owner of the fern harvesting business asking to purchase a car trailer load of his fibre (Dicksonia squarosa).  He kindly offered for me to back up the trailer and load up for free from fibre that had fallen off his conveyer belt.

On arriving home I immediately observed that there was a lot of fine dust within the fibre, so I put it through an 1/8^th. inch mortar sieve.  By the time I had processed the whole load only 1/3^rd. of the volume remained. Fortunately no one down- wind complained about the dust.  The fibre was mixed with bark (3 parts bark to 1 part of fibre).  All of my paphs were promptly repotted into this mix.  In the months following the growth was astoundingly good, significantly superior to results obtained using pure bark.

Barry Fraser was in awe. Unfortunately all good things seem to come to an end.  After about two years the fern harvesting business was sold to overseas interests, and they had no interest in supplying me. So, it was back to using bark up until recent times when I met Alan and Rob of Fernwood.

I was overjoyed to meet them, because I, again, had access to fern fibre. They were very pleased to meet me, because they were initiating their involvement in supplying fern fibre as an orchid growing medium.  I was able to supply them with a lot of information from my prior experience, and I continue to advise them. The major part of my involvement with the Fernwood guys is growing trials.  They need to know what works and what doesn’t.

Most of my work involves paphiopedilums.  Here is a summary of my findings to this date (July 2018).  The fibre used is NZ native fern fibre straight from the bag.  It is a high quality product, far superior to (and a different species) the product that I had access to in the 1990’s.

1. A mix of 3 parts bark and 1 part fibre is significantly superior to bark alone
2. Undiluted fibre is significantly superior to a mix of 3 parts bark

The following observations should be noted:

1. Water applied to a pot containing Ponga/NZ native fern fibre remains evenly distributed through the mix between irrigations due to its capillary action.  In other words, the fibre at the base of the pot remains just as moist as the fibre at the top.  It dries evenly throughout.  You must understand this to fully appreciate the following points.
2. Ponga is a fine fibre that has a profusion of fine hairy processes.For this reason the surface area of fibre in contact with orchid roots is considerable, greatly assisting the uptake of fertilizer.
3. Judging watering is easy.You don’t have to lift a pot.  Simply judge the moisture content by looking at it.  If some of the fibers are showing brown you need to water, and probably should have done a day or so earlier.
4. Some plants dry quicker in the pot than others.It is not until repotting time that you discover that some plants have been continually over or under watered.  When potted in fibre you can spot it at a glance and take remedial action.  I spot water those that need irrigation earlier than others.
5. If you accidentally pot a paph. a little high in the pot you don’t lose roots if they emerge on top of the mix.The roots continue to grow and will eventually dive down into the mix.

If you try growing in fibre (and you should!), consider the following:

1. Ponga is exceptionally slow to decompose.  In forests fibrosa logs will lie pretty much intact for decades!  It will last longer than bark in the pot, but we don’t know how long yet.  I have paphs. growing great roots in fibre that has been almost 3 years in the pot.
2. Much of the nitrogen you introduce to your pots is consumed by bacteria that decompose your bark.Because fern fibre is so slow to decompose, I think it is fair to assume that that there are much fewer bacteria of this type present in the pot when using this potting medium.  I therefore fertilize at a low concentration. I water thoroughly overhead by hand, and immediately follow with fertilizer applied from a watering can.  I am using Dyna-Grow Grow 7-9-5 together with Pro-Tect 0-0-3, both at a dilution of 1:2500. This works very well for me.  Some time I will arrange for a leaf analysis to see if I need any fine tuning.
3. Because fibre absorbs and retains a lot of water (it also holds adequate air), you require less frequent watering.For example my paphs. in 3.5 x 3.5 x 4 inch pots my last two watering were 13 days apart during mid-July, which is our coldest month in New Zealand.  Do not over water.  It will cause you problems, just as it does in bark.  Do not over pot.  Hobby growers are so often guilty of both.
4. Particularly being new to the use of fibre, it is a great idea to check root health periodically.When you pull the root ball from the pot you will find that the root ball remains intact.  There is no bark to spill all over the place!
5. Although your fibre has been fumigated prior to import, it is possible that some spores of liver warts will survive and germinate after potting.After watering in your repotted orchid I suggest that you distribute some dolomite over the moistened fibre. During subsequent watering most of the surface dolomite will remain at the surface providing a slightly alkaline environment that prevents germinationof these weeds.  Perhaps an annual application of dolomite could be a good strategy.

What other orchids grow well in NZ fern fibre? Here is a list of what I have either grown or am growing in this material:  phalaenopsis, phragmipedium, dendrobium, odontoglossum, oncidium, stenoglottis.  I expect that most genera that enjoy moist conditions and don’t like to dry out too much will benefit from this medium.  I have tried, and have been unsuccessful with cattleyas, but I have heard of two growers who are very successful.

My suggestion is for you to give fibre a try.  Be both excited and cautious.  Always monitor your orchids closely with any significant change that you apply. I will NEVER return to using bark!!!  If you try fibre for growing any of the above recommended genera, if your conditions are satisfactory, and if you follow my guidelines, then I think your experience will be similar.

~ Many thanks to Selwyn Hatrick for providing this guest blog post