We’ve struggled for years to grow some of the exceptional forms of Hart’s Tongue fern, Asplenium scolopendrium in our hot, humid climate. One cultivar that we’d long been enamored with is Asplenium ‘Keratoides’. After killing nearly everything we had, we stuck one in the crevice garden, where, to our amazement, it has performed marvelously. It seems that this species needs to grow near rocks to thrive, and the alkaline nature of our crevice garden is obviously to its liking.
We’ve been fortunate to grow a huge number of hardy garden ferns through the years, but it’s hard for any to top the amazing Pleopeltis lepidopteris, to which, we’ve given the common name, Brazilian hairy sword fern.
Below is a patch at JLBG, composed of three individual clumps, looking great, despite the ravages of summer. This sun-loving lithophytic (rock grower) also grows fine in well-drained soils. In habitat, it hails from the sandy, acidic coastal (restinga) habitats in southern Brazil (Rio Grande du Sul). Our plants came from our friends at the former Yucca Do Nursery, who made a beach front collection in Brazil in 2012. It doesn’t appear that fern had been in cultivation prior to that time.
The 18″ tall x 2″ wide, rigidly upright fronds emerge covered in thick silver hair, to which I can now relate. As the fronds age, the hair thins and the green leaf surface becomes more visible. Pleopeltis lepidopteris spreads slowly from surface rhizomes. We’ve grown this evergreen Pleopeltis in our rock garden since 2012, where it has thrived even through winter temperatures of 7 degrees F. Hardiness Zone: 7b to 9b, at least.
Back in the 1970s, when I was specializing in house plants, one of my favorites was the epiphytic fern genus, Aglamorpha. These staghorn relatives made delightful hanging baskets, despite being far outside the bell curve in regards to recognizability to most gardeners.
Over the years, as I migrated more to hardy perennials, I gave up most of my house plants, but not before trying most of them in the ground. As you can imagine, aglmorphas were a failure, but I never gave up on the idea of finding a winter hardy one.
Fast forward some 40+ years later, I spotted an aglamorpha-like fern in the crowded cold frame at England’s Pan Global Plants. Examining the tag, which read, Drynaria sinica, led me down another rabbit hole, where I discovered that the genus Aglamorpha and Drynaria had recently been joined due to a botanical merger.
In the new group of 30+ species, one, Drynaria sinica, came from an elevation of over 12,000’…a certain sign of potential hardiness. My purchase made it through both the inspection and shipping process, and now thrives in our rock garden, where it sailed though 11 degrees F this winter. Despite a recent name change to Drynaria baronii, we are very excited about this hardy epiphytic fern, and look forward to eventually having some to share.
If you’re a nursery, and you’d like to offer ferns, the plants at your disposal are somewhat limited. A large majority of ferns sold in America are still sadly dug from the wild. When you see a catalog listing primarily these ferns together…usually an very inexpensive prices, you can be pretty much assured they were dug from the wild: Osmunda regalis (royal fern), Osmunda cinnamomea (Cinnamon Fern), Polystichum acrostichoides (Christmas Fern), Matteuccia Matteuccia struthiopteris (Ostrich fern), Adiantum pedatum (Maidenhair fern), Athyrium filix-femina (lady fern), and Onoclea sensibilis (Sensitive Fern). These ferns are often sold bareroot, to save the nursery the expense of having to pot the collected plants, many of which are so large, they won’t fit in small containers.
The other majority of ferns in the market are produced by tissue culture, either by a couple of labs in Florida, one in Texas, and one in Holland. Without the amazing work of these labs, the fern selections available to homeowners would be limited to the wild collections. Even with their amazing work, these labs must focus on well-known ferns that sell in very large numbers.
While we make use of the lab offerings, we also made a commitment over 30 years ago to grow many of our own ferns from spores. Outside of a few small fern specialists, there are few nurseries who grow their own ferns from spores, since this is the most costly and time consuming option. The reason we do this is so that we can offer fern species and selected forms that are otherwise unavailable.
Below is a quick summary of how the process works. Fern spores (fern equivalents of seed) are collected through the summer, and are dried in paper envelopes until they separate from the foliage. They are then sown in pots with potting soil that is sterilized here, and then sealed in ziploc bags. The spore takes from 1 month to 6 months to germinate. Once the spores germinate, they are ready to have sex…a process that is reversed from more modern evolved flowering plants.
To assist the ferns have sex, we gently add water to the newly germinated sporelings, since ferns (other than desert ferns) only have sex while they are swimming. The water is swirled around to mimic the feel of a whirlpool, then the bags are then resealed, and put in the dark where they are subjected to a near constant montage of Barry White music.
Within a few weeks, tiny fern fronds begin to emerge. At this point, the ziploc bags are opened to allow the humidity to equalize with the ambient air. After another couple of weeks the pots are removed from the ziploc bags. If the spore were viable and cleaned well without contamination, and if germination was good, there will be up to several hundred plants per pot.
After a few weeks, the sporelings are transplanted into a cell pack flat. Here they grow out for another few months until they are ready to be planted into our 1 qt. pots, in which they will be sold. In all, it’s about an 18 month process, and a good bit of labor. We’re really quite passionate about our fern collection at JLBG, which the visiting British Fern Society declared one of the largest/most diverse in the world. We hope you find the results worthwhile.
Since ferns are one of the groups on which we focus our ex-situ conservation efforts, we have collected a huge number of species and selections from around the world. One that has continually frustrated us is the miniature rock fern, Asplenium trichomanes. Although this small gem is native to every continent except Antartica, we have struggled to keep it alive.
In our travels, we have collected it from Europe to Africa, but have also managed to kill all of those collections in the garden. Since our first attempt in 2004, we have now killed Asplenium trichomanes 16 times. We believe, however, in the late JC Raulston’s mantra, “Unless you are killing plants, you aren’t growing as a gardener.” The key is how many times do you continue to try before giving up?
We’re pretty stubborn as long as we feel we keep learning from each failure. Our latest accession of this species, which came as spores from Russia’s south coast, is actually thriving in our crevice garden, where the pH is north of 8.0. It seems that the crevice habitat is the answer.
One of our favorite of the US native (Central Texas) desert ferns is Pellaea ovata. Here is our clump in the crevice garden looking quite nice this week. This is scheduled to return to the Plant Delights catalog in January. Hardiness should be at least Zone 7b and south.
