Ferns are enjoying a surge in popularity these days. Using ferns as garden ornamentals is not a new concept. The UK fern craze of the Victorian times (coined ‘pteridomania') seemed to be the starting point with the discovery of hundreds of unique forms of native ferns. By the turn of the century, the craze subsided and ferns, while not falling completely out of fashion, did appear to lose their spark. Ferns became a plant of the specialist gardener. In the 1980s and '90s, ferns once more started to gain popularity. The discovery of new species in China, especially those with more colourful fronds with touches of grey, red and wine, suddenly upped the ante. The present day increase in fern popularity follows on the footsteps of the current Hosta craze. Hosta are perhaps the premier foliage plants grown by gardeners and with their tolerance to sun or shade (depending on the selection), they can be used in a myriad of garden situations. However, gardeners now needed some plants to contrast with their ever-growing Hosta collections. Ferns were the obvious choice. Today, ferns once more are becoming a mainstay in the garden scene.
Most gardeners associate ferns with shade. Certainly, the vast majority do grow in the shade of forests and rocky outcrops. For gardens with shade issues, ferns come highly recommended. But not all gardeners have to deal with shade and yet, they would like to incorporate ferns into the landscape design. Are there any ferns that can tolerate significant sun? The answer is yes! However, some soil amendments are required to have success.
The key to growing ferns in sun is maintaining adequate soil moisture. Many ferns grow in shade simply because the soil stays moister there than in full sun. If your have a growing area where the soil stays moist, then ferns in sun is a distinct possibility. Highly organic soil will help ensure better soil moisture. Maybe you have a naturally occurring moist pocket or a stream running through your property. Perhaps you have a sprinkler system that helps maintain evenly moist soil. Some gardeners even have man-made bog gardens. Any of these situation can allow for ferns to be grown under full sun situations, especially in more northern gardens. In southern gardens, the midday sun is probably still too intense, but as long as the ferns are shaded midday, they can tolerate morning and late afternoon sun. While many ferns can handle considerable sun if the soil remains evenly moist, some are better than others. Here are some of the most sun-tolerant species.
The genus Osmunda only contains three species; the cinnamon fern, O. cinnamomea, interrupted fern, O. claytoniana and the royal fern, O. regalis. All of these ferns prefer moist to wet sites. Royal ferns are known to actually grow into the flowing water of streams. Due to their high moisture requirement, these species will not tolerate any drought however they will tolerate full sun. In fact, in my local area, cinnamon ferns typically grow in full sun. They are also very wind tolerant and will grow quite close to the ocean. Royal ferns also tolerate full afternoon sun and have the advantage of bronze-coloured spring growth. Interrupted fern seem to appreciate shade from midday sun but will certainly tolerate full morning sun. All of these species are deciduous and turn lovely shaded of yellow, copper to bronze in the fall. These are not small ferns; most reach at least 3 feet, but they are not runners, rather they form large vase-like clumps. They are hardy to at least zone 3.
Details of the cinnamon fern
Above left is the royal fern while to the right is the interrupted fern
Among the genus Athyrium, the best species for sun is the lady fern, A. filix-femina. There are many named cultivars of this fern, many which date back to the fern craze of the Victorian era (this was the most popular fern at the time). In warmer climates, a little protection from the hottest midday sun will go a long way to prevent browning of the frond edges. Again, locally, this fern often grows on open, exposed headlands near the ocean as well as exposed mountain tops. This is a mid-sized, deciduous clumping fern reaching about 2 feet and is hardy to zone 4. Perhaps in warmer climates you would be better to grow the southern lady-fern, A. asplenioides as it is better able to cope with sun and heat (again assuming the soil stays moist).
Above is the typical lady fern while below are some of the more interesting cultivars 'Frizelliae' and 'Victoriae'
The common ostrich fern, Matteucia struthiopteris, is reputed to be very sun-tolerant. I grow mine in full sun but then I don't have the excessive heat of more inland areas of North America. I expect that a little shade from the hottest time of the day might be advised in warm areas. Few ferns are as architectural. The tall ( to 5 feet), narrow, vase-like habit and bright green color is superb. At times this fern will run and produce new plants at varying distances from the parent so has the potential to be a bit of a pest, but generally it is easy to control. This zone 3 ferns is deciduous.
Ostrich fern earlier and later in the season
Both the male fern, Dryopteris filix-mas, and the scaly (golden) male fern, D. affinis, are among the most sun-tolerant of the evergreen fern species. Both are clumpers and can achieve a considerable size with fronds reaching 4 to 5 feet. The fronds are quite leathery and deep green. There are many named selections of species. Like the lady fern, many of these selections date back to the Victorian times. Both species are hardy to zone 4.
Male fern (left), the cultivar 'Cristata' (middle) and scaly male fern (right)
In the south, an excellent fern for moist sun is the southern shield fern, Thelypteris kunthii. They not only tolerate sun but can easily cope with high heat and humidity. This slow to moderate running fern is deciduous, disappearing in winter. The fronds reach 2 to 4 feet. Over time, the spreading habit of this fern will lend itself to be a suitable groundcover. They are only hardy as far north as zone 7.
Another good sun-tolerant fern for southern climates is the southern wood fern or Florida shield fern, Dryopteris ludoviciana. This fern is semi-evergreen with fronds reaching to 4 feet. It slowly spreads to form a reasonable groundcover. It is a little hardier than the southern shield fern, being hardy to zone 6.
Southern wood fern (left) and southern shield fern (right)
Braken fern, Pteridium aquilinum, can certainly tolerate full sun and actually prefers sun to shade. It is with some reservation that I mention this species as it is very aggressive and rapid-spreading. From the rhizome arise large, individual, triangular-shaped fronds atop 2 to 5 feet stems. It is a deciduous species and can actually tolerate some drought. Use it in areas where its rambunctious nature will not out compete more timid neighbors. In fall, the fronds turn an attractive bronzy-brown. It is hardy through zone 3.
Details of the braken fern
There are a host of small semi-desert, evergreen ferns that are specifically adapted to sun and drought. These are the lip ferns, Cheilanthes spp. and cloak ferns, Notholaena spp. and Astrolepis spp. These are small tufted ferns with somewhat fuzzy, grey-green foliage. Cheilanthes have narrow fronds while Notholaena and Astrolepis are triangular in outline. All are generally under 30 cm. In the wild, Arizona is the place to see these ferns. In the garden, grow them in rock garden settings or xeriscapes. Most are hardy to zone 6 but require a rather dry climate (especially in winter) to thrive.
Examples of the semi-desert ferns include Cheilanthes tomentosa, C. lindheimeri and Astrolepis sinuata
As you can see, ferns are far more versatile than you would think. With their lovely foliage and forms, they can be used as a garden contrast in a wide variety of situations. Keep them moist and they will reward you in shade or sun.
I would like to thnak the following members for the use of their pictures: Cretaceous (Cheilanthes lindheimeri), Equilibrium (Osmunda claytoniana and Dryopteris filix-mas 'Cristata'), ericmg01 (Dryopteris filix-mas), gregr18 (Athyrium filix-femina 'Victoriae'), RonniePitman (Astrolepis sinuata), SecludedGardens (Matteuccia struthiopteris), weebles64 (Athyrium filix-femina 'Frizelliae'), wooffi (Dryopteris ludoviciana) and PurplePansies (closeup of Athyrium filix-femina).