The Autumn fern, Dryopteris erythrosora, is a fairly compact fern grown outdoors in USDA hardiness zones 5-9.
Due to its size and growing requirements, it can be grown indoors. Though it also does well outdoors in a suitable spot in many regions outside its native area in Asia.
If growing indoors, it is important to think about the conditions this fern requires, so you choose the right place to locate it and give it the right care.
What is Autumn Fern?
Autumn fern is a herbaceous perennial that will grow to around 18-24 inches in height and spread. It has a dainty look with its filigree foliage and yet is much tougher and less fussy than it looks.
This fern is also known as copper shield fern and Japanese shield fern. It is prized for its attractive foliage and the fronds are a coppery pink when they are young before they mature to a mid-green hue. New young fronds with their vibrant hue can grow throughout the spring and summer growing season.
The coppery tone to the foliage, like the foliage on fall trees, is what gives this fern its common name of autumn fern. There are some named cultivars with even more coppery-red tones – like one called ‘Brilliance’ for example.
These plants will die back in winter in cooler climates though tend to be semi-evergreen in such locations. They can be fully evergreen in warmer climes and sometimes indoors, though usually they will still lose at least some fronds in winter.
Where to Grow Autumn Fern
Autumn fern can be grown indoors whether or not you live in an area where it can be grown outdoors successfully.
Its relatively compact size and unfussy nature mean that it is quite well suited to growing in pots indoors.
But you do need to consider environmental conditions like light, temperatures, and humidity when deciding where to place it in your home. You also need to remember that it often dies back over the winter months.
It is important when choosing where to place this fern within your home to choose a spot where the plant won’t be damaged by harsh, direct sun. A position where there is bright but filtered light, shaded during the afternoon, is ideal. So a north or east-facing windowsill can work well.
Temperature & Humidity Requirements
One of the good things about the autumn fern is that it is tolerant of a wide range of temperatures. It cannot only cope with cold in winter but also does well in warm temperatures too, as long as reasonably high humidity is maintained.
Autumn ferns do need a humid environment, so placing one in a steamy bathroom may be ideal. You might also grow this fern in a terrarium so that humidity can easily be maintained.
To raise humidity where this is required, you can group houseplants together, place a tray filled with pebbles and water below your pots, and/or mist your fern regularly when the air is dry.
Soil/ Growing Medium
As you choose a growing medium, be sure to consider where these ferns grow in the wild. They enjoy a woodland habitat in their Asian native range, so the growing medium should resemble as closely as possible the humus-rich woodland soil on those woodland floors.
Of course, it should be moist yet free draining. It should also be high in organic matter and ideally have an acidic pH.
Planting Autumn Fern
You can obtain an autumn fern by purchasing one in a pot, or by propagating an existing autumn fern through division or using its spores.
Choose a container large enough to accommodate the existing root system, with some room to spare. A clay or terracotta pot with large drainage holes at the base is ideal.
Caring for Autumn Fern
Autumn ferns require little care outdoors but indoors will need more of your attention – particularly when it comes to watering.
Regular watering is essential when growing autumn ferns in pots indoors. Remember that container plants often require more water than those growing in the ground.
You need to keep the growing medium moist throughout the growing season. But it should not be saturated, as waterlogging can also cause issues for this fern.
Autumn ferns growing in a garden will not typically need feeding at all, beyond the application of an organic mulch each spring.
But those growing in containers will need to be fed more often. Feed container autumn ferns once a month through the growing season with an organic, balanced liquid plant feed – a compost tea diluted to half strength can work well.
You may be tempted to remove the old dead fronds when these wither over the winter months. But you should not prune these off. Rather, you should leave these in place to protect the crown of the plant during the dormant period.
Leave the dead fronds in place, pop your plant in a cool location, then if you wish, remove the dead fronds carefully in the spring, taking care not to damage new growth emerging at this time.
Autumn ferns are not prone to pest or disease problems, so are often hassle-free. However, they can experience a range of issues related to improper growing conditions or care. So make sure everything is right in those areas to avoid common problems and pitfalls.
Mealybugs, scale insects, aphids, and other common houseplant pests may sometimes bother autumn ferns, but these will rarely become a serious issue.
Smaller fronds may be a sign that an autumn fern needs repotting. Look out also for roots appearing through the hole or holes at the base of a container.
Autumn ferns should be repotted when they become root bound and moved to a slightly larger container.
Though they are tolerant of being root bound to a degree, if their container is too restrictive then eventually issues with waterlogging or water shortage and fertility are likely to occur. So pot up autumn ferns before this becomes a problem.