We’ve long loved the fern genus, Pteris (pronounced terrace), but struggled for years to find any that were winter hardy here in Zone 7b. That changed with our 1996 Chinese expedition to Yunnan Province, and later a subsequent expedition by gardening friends to Sichuan Province. On both trips, high elevation collections of Pteris vittata were made that were much more cold hardy than anything from previous introductions. Both introductions have thrive here since the late 1990s. What we also love is that these ferns thrive in full, baking sun. Even now, in mid-July, these ferns look absolutely amazing in the gardens. Plant Delights currently has one of these amazing selections for sale. Hardiness is Zone 7b-10b.
Here’s a recent image from JLBG, giving an idea of what’s possible when being thoughtful of textures and colors when planting. Plants include Iris x hollandica ‘Red Ember’, Heuchera ‘Silver Scrolls’, Carex ‘Bonnie and Clyde’, Thelypteris kunthii, and Juniperus chinensis ‘Parsonii’.
Looking good in the garden this week is the amazing fern, Dryopteris x australis. This rare fern is a US native…despite the confusing name, hailing from only a few scattered locations from Virginia west to Arkansas. In reality, the name “australis” means from the south. This splendid specimen grows in both sun and shade, and tolerates both wet and dry soils. Hardiness is Zone 5a-9b.
We often talk about the amazing group of hardy asparagus ferns, so here we go again with a few that are looking particularly great now.
The first image is our dwarf selection of Asparagus cochinchinensis ‘So Fine’. This is our new dwarf selection from our original collection from Korea’s Mt. Chuwang. Hardiness is Zone 4b-8b, at least.
Asparagus tenuifolius ‘Vodice’ has proven to be an amazing garden specimen with a tight compact habit. This is our collection from Vodice, Croatia. It’s amazing that this incredible species is completely absent from gardens. We have no idea about winter hardiness, but would expect Zone 5/6 at least.
The amazing Asparagus sprengeri ‘Graham’s Cracker’ just continues to amaze us. This dwarf selection of the hanging basket asparagus fern from NC plantsman Graham Ray, has been reliable for years in Zone 5b, without the benefit of mulch or any other protection. We find it a superb textural contrast for bolder foliaged perennials.
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.
We love the tardily deciduous Ctenitis subglandulosa ‘Hoshizaki’, which remains looking great in the garden as we pass the winter solstice. This truly elegant fern came to us from fern guru, Judith Jones, who got it from California fern guru, Barbara Jo Hoshizaki. The airy texture and ease of growth make this a fern we wouldn’t garden without. Sadly, we offered this Asian native (Bhutan through China) once through Plant Delights and very few people purchased one, so we had to discard the remaining crop…ouch! So very sorry you missed a true gem. Hardiness is Zone 7a-8b (guessing).
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.
Looking superb this week is our great native fern, Thelypteris kunthii (southern shield fern) So what is a kunth? In fact, this fern gets its name from German taxonomist, Carl Sigismund Kunth (1788 – 1850). Kunth was one of the first people to categorize North American plants, mostly from the collections of German botanists, Humboldt and Bonpland. Thelypteris kunthii was named in his honor in 1967, long after Kunth’s death, by American botanist Conrad Morton (1905-1972). In our gardens, it thrives in both light shade and full sun…an amazing plant.
One of the fabulous ferns in our garden during the summer months is the sun-tolerant Dennstaedtia hirsuta ‘Sohuksan’. This fabulous specimen came to the US from a 1985 collection from Sohuksan Island, South Korea, where it was discovered by a team of intrepid plant explorers that included horticultural legends as Barry Yinger, the late Ted Dudley, the late J.C. Raulston, the late Peter Wharton, Young-june Chang and Kun-so Kim. The group had left the mainland for the several day ferry ride to this remote island, landing just ahead of a typhoon, which resulted in severe injuries disembarking from the ferry. After riding out the typhoon in minimal shelters, they awoke to a treasure trove of amazing plants. We are so glad to keep the memory of this amazing trip alive in gardens with some of their great plant introductions.