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My Ongoing Orchid Trial with New Zealand Tree Fern

By Allan Watson, August 19, 2024

As an avid orchid hobbyist, I’m always interested in improving my growing techniques to improve the health, yield and size of blooms. With over 1,000 plants in my collection, I have plenty of opportunity to experiment and compare. My particular interest is in Miltoniopsis and having enough plants (including awarded ones) to reference against I feel like I have a pretty good baseline on what works and what doesn’t. If I may take a moment – be it a humble one – to brag a bit, I grew the only 2 Miltoniopsis to receive awards from the Orchid Council of New Zealand in 2018 and 2019.

Miltoniopsis Breathless ‘From Love’HCC/NZOC

Miltoniopsis Taranaki PrideAM/NZOC

Lucky for me I live in New Zealand, home to arguably the best quality tree fern on the planet. How do I know? Just 9 months into my planned 2 year growing trial I’m already seeing amazing results – but more on that in a bit. My good friends at Fernwood NZ, Ltd have been harvesting and processing tree fern for over 3 decades. I’ve historically grown in a bark-pumice mix – and like I said, achieved what I consider to be good results. One day we got to talking about the successes other growers were reporting. I’m not sure whose idea it was but we ended up agreeing that a semi-scientific trial would be both fun and educational. One thing about all the orchid hobbyists I’ve met over the years – our number one goal is to help each other be better growers. By bringing a bit of rigor to the comparison of growing mediums, I figured my experiences would be beneficial to the broader orchid community.

So I set off on my journey to compare growing in Fernwood tree fern fiber to growing in a bark-pumice mix. I committed myself to a two-year trial starting with 15 Miltoniopsis growing in my standard bark-pumice mix next to 15 of the same cross growing in tree fern fiber. To make the results as closely comparable as possible, both sets of plants were grown side-by-side under the same conditions with the same watering frequency and fertilizing regimen.

Miltoniopsis Rene Komoda ‘Pacific Cloud’

First Checkpoint – 4 months

Both plants potted on the same day. At four months there was already a noticeable difference between plants in Fernwood tree fern fiber and those in the bark-pumice mix. The plant on the left is in a 3-part bark, 1-part pumice mix. The plant on the right is potted in 100% Fernwood tree fern fiber. The plant in tree fern appeared to be darker and healthier. The plant was better developed having more growths and denser foliage. This was consistent across all 15 pairs.

Miltoniopsis Rene Komoda ‘Pacific Cloud’

Second Checkpoint – 6 months

At six months the advanced development of the plants grown in Fernwood tree fern fiber encouraged me to remove one pair from their pots to compare root structure. The plant on the right was grown in tree fern and exhibits a significantly denser, larger root mass – not unexpected considering the differences in overall growth.

Miltoniopsis Robert Jackson ‘Wild Thing’

Third Checkpoint – 6 months

My third checkpoint afforded the opportunity to compare flowers as many of my trial pairs were in full spike. Flowers of plants grown in Fernwood tree fern fiber are consistently larger with a higher number of inflorescences. The flower on the left is from the plant in tree fern and the one on the right is from the plant in bark-pumice mix. The difference is just over 10% increase in size.

As my trial has progressed, I’ve been compelled to move more of my Miltoniopsis collection to tree fern beyond those pairs dedicated to the trial. Many of those are in bloom as well with similar results. Whereas my past experience has observed flowers averaging 2-1/2” across, plants growing in Fernwood tree fern fiber as in the photos below have been delivering flowers as large as 4” across.

Mps Benito ‘Eternity’

Mps Drake Will ‘Ruby Falls’

Mps Mary Saunders ‘Annie’

Mps Yoshiko Tempo

As my Miltoniopsis trial continues, I have expanded my use of tree fern fiber across my collection. Specifically I now have Odontoglossum, Dendrobium, Promenaea and Cattleya all growing in the substrate. Not surprisingly, early results have been encouraging and I hope to be able to report on those in the not too distant future.

While I have obviously been very pleased with my results and have expanded my adoption of tree fern as the growing substrate for much of my orchid collection it is worthwhile to remember that everyone’s growing conditions are different. Coupled with individual tendencies around watering and fertilizing, results can vary from grower to grower. If your current regimen is working – by all means continue what you are doing. Hopefully my experiences will encourage you to experiment. I’m certainly glad I did. And if your current approach isn’t yielding the results you’d like to see, you may find tree fern fiber an exciting alternative.