Arrange your Asparagus

Asparagus virgatus is undoubtedly one of our favorite textural perennials. How many evergreens do you know that thrive in shade with such an amazing texture, and can be cut for flower arrangements. If you’ve ever worked with cut flowers, you’ll recognize this as “filler” that you purchase with your flowers to add 3-D texture to your arrangements. Few people, however realize that it’s an easy-to-grow garden perennial.

Although in the wild, it grows along streams, it has proven to be one of the most drought tolerant plants we grow. In terms of light, an hour or two of morning sun is fine, but this South African asparagus species much prefers light shade all day. Unless winter temperatures drop below 10 degrees F, the amazing foliage stays evergreen. Hardiness is at least Zone 7b and warmer.

Asparagus virgatus

Christmas in June

While doing some local botanizing recently, we ran across this fascinating form of our native Christmas fern, Polystichum acrostichoides. Not only was it more compact than any others in the area, with more “orderly” fronds, but it also showed none of the typical terminal spore production that would be expected this time of year. Since this was from a future development site, the plant was rescued, and is now at JLBG under evaluation. The second photo is more typical plant for the species for comparison, growing at JLBG.

Mama…where do fern babies come from?

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.

Finally, a ferner adapts

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.

Lithophytes, epiphytes, tigers, and bears…oh my

Just out in the garden in early January and wanted to share photos of a few of our favorite evergreen ferns that would rather not be growing in the ground. In our garden, these are all growing within a few feet of each other.

Each of these ferns are epiphytes, which grow attached to a tree, or lithophytes, which grow attached to a rock. None of these ferns actually need soil to grow, since they get their food and water from the atmosphere and accumulated organic debris. Epiphytes, however, don’t get nutrients from their host plant…only physical support.

All epiphytic ferns thrive in hanging baskets, especially the spaghnum-lined type, since this most closely mimics their natural preferences. In our case, we are a bit colder than their native haunts, so for us, we force these ferns to reside in the ground since that gives them a bit more protection during severe winter temperatures. The key for epiphytes to survive in the ground is to have very loose, organic soils and always plant them on a steep slope.

Neolepisorus fortunei ‘Green Ribbons’ is our 2017 introduction of a Chinese native epiphytic fern.

Neolepisorus fortunei ‘Green Ribbons’

Pyrrosia lingua ‘Hiryu’ is also an epiphytic fern, native to Japan.

Pyrrosia lingua ‘Hiryu’

Lastly is Polypodium vulgare ‘Ulleung Island’. Instead of being an epiphyte, this evergreen fern is a lithophyte. Lithophytes are classified as either epilithic (growing across the rock surface) or endolithic (growing in cracks or crevices). Since we found this in the wild, growing across the surface of a giant rock, this fern is an epilithic lithophyte…say that three times fast. This is our 1997 collection from an island, far off the coast of South Korea.

We hope you’ll explore these unique ferns in your garden.

Polypodium vulgare ‘Ulleung Island’

Garden hookups

We always love it when unexpected garden hookups yield unexpected results, and such was the case recently when, under the cover of darkness, two of our holly ferns took a liking to each other. The result of this conjugal interlude is our first hybrid of Cyrtomium fortunei x Cyrtomium falcatum, that we’ve named Cyrtomium x fortatum Spornication. The habit of the hybrid is intermediate between both parents. Now, we’ve just got to figure out how to get it propagated in order to share.

Cyrtomium x fortatum Spornication

Mr. Butterfield’s Fern

We love the evergreen holly fern in all it’s species and forms. Cyrtomium falcatum ‘Butterfieldii’ is looking absolutely stupendous in the garden this month. This easy to grow shade lover glistens all winter with its glossy foliage with fancy serrated edges. Hardiness is Zone 7a-8b.

Mama Mia…that’s a lotta ferns

We love fall and winter, when Woodwardia orientalis ‘Mama Mia’ starts producing baby ferns on the old foliage. Mama Mia can be propagated from the plantlets, but in our cold winter climate, the babies rarely mature unless taken indoors for the winter. The evergreen foliage of Woodwardia orientalis will show damage at about 10 degrees F and Zone 7b is the northern-most range of its cold hardiness.

Leaping Lepisorus

We love ferns of all types, but especially the single-leaf types. Our clump of the Chinese Lepisorus macrosphaerus really stands out in the fall and winter garden. In the wild, most lepisorus grow on rocks or tree trunks, but most we’ve grown have adapted well to growing in the soil. They tend to thrive better when growing on slopes, and in well-drained soils.

Lepisorus macrosphaerus

Holy Giant Holly Fern

Cyrtomium macrophyllum is looking particularly fabulous this year. This is a little-grown holly fern with a wide range from India to Southeastern China that can be found at elevations from 2,500-8,000′. The bold textured fronds arch outward to make a 2′ tall x 2′ wide clump that is semi-evergreen in most winters. It seems as if we will get good spore set this year, which may mean another offering since the last time PDN had it to share in 2003.

Celebrate Plasticity

We live in an age where many plastic products are vilified, but every now and then, we find a reason to embrace the texture of plastic. Such was the case in 2008, when we visited The Missouri Botanic Garden. Walking through one of their greenhouse, I spotted an odd holly fern, planted in the middle of a large mass of Cyrtomium falcatum. The foliage appeared much thicker and more glossy than any of the other plants. The staff was kind enough to share a piece, which we subsequently named Cyrtomium ‘Plasticity’. We theorize it is probably a ploidy mutant with an extra set of chromosomes that would account for the extra thickness and glossiness. Here is a photo from the gardens this week, where it has become a favorite.

Upside down Spider Fern

Arachnioides standishii is one of our favorite garden ferns. This particular collection comes from Japan’s Mt. Daisen. The common name is Upside down fern since the leaves appear to be attached inverted. Production is always challenging since spore don’t ripen until after Christmas. The foliage remains evergreen until temps drop below 10 degrees F. Hardiness is Zone 4-8.

Dryopteris erythrosora ‘Brilliance’

Dryopteris erythrosora BrillianceHere’s a new photo of the evergreen Autumn fern, Dryopteris erythrosora ‘Brilliance‘ as it emerges in the woodland garden with its stunning new growth.