Japanese painted ferns, Athyrium niponicum, are beautiful hardy ferns often grown in gardens for visual appeal in a shady spot. Growing these ferns indoors in pots is more challenging. But with the right placement and care it is possible to do so.
What is Japanese Painted Fern?
The Japanese painted fern, also known as the painted lady fern is an east-Asian, rhizomatous fern species with attractive foliage.
It is a more colorful alternative to green ferns like Boston ferns or ostrich ferns that you might grow. The fronds are silvery, with grayish green on them, and purplish midribs. This variegated look gives them great visual interest indoors or outside in a garden.
Where to Grow Japanese Painted Fern
Whether you want to grow Japanese painted ferns in your home or in your garden (they can be grown outside year-round in USDA zones 3 through 8), you need to determine the conditions they require to place them correctly.
Light Requirements
Japanese painted ferns are extremely tolerant of low-light conditions. Outdoors they can be grown either in full shade or partial shade. Indoors, it is best to place them in a reasonably bright location, but certainly to keep them away from direct light.
Temperature & Humidity Requirements
Temperatures for Japanese painted ferns should ideally be kept at all times between around 12 and 26 degrees Celsius. But it can cope with much lower temperatures when growing outdoors and is hardy to far below freezing.
These ferns do like a reasonably humid location, but not one that is quite as humid as that enjoyed by other ferns such as maidenhair ferns, for example. The ideal humidity for these ferns is actually between 50 and 60 percent.
Soil/ Growing Medium
The key thing to remember when choosing a growing medium for painted ferns is that they need a substrate that is rich in organic matter, which mimics the humus-rich woodland soil of their natural environment. A peat-free potting soil with added homemade compost or leaf mold might be ideal.
The medium must also be moist yet free draining. Free draining conditions are essential so that waterlogging and root rot do not occur. Overly soggy conditions can also cause several other fungal issues to arise with these ferns.
Planting Japanese Painted Fern
Japanese painted ferns can be purchased as potted plants. There are several different cultivars to choose from including ‘Pictum’, ‘Burgundy Lace’, and ‘Wildwood Twist’ to name a few examples. It is also possible to propagate an existing fern of this kind through rhizome division in spring.
When potting up a Japanese painted fern into a new container, make sure that you choose one just a little larger than the present pot, and large enough to accommodate the current root system with just a little space around. Ensure the plant sits at the same level that it was at in its previous location.
Caring for Japanese Painted Fern
Japanese Painted ferns are extremely low-maintenance plants outside. Indoors in pots, they will need more care. The main jobs to think about when growing these ferns are watering and feeding, though there are a few other elements of care to consider.
Watering
Watering is very important for most plants grown indoors and these ferns are no exception. Make sure that you water regularly. When the top few centimeters of the growing medium seem dry to the touch it is time to water again. Water deeply but make sure excess water can drain away freely.
Try to water the growing medium where the water is required by the roots, and aim to avoid getting water on the fronds wherever possible.
Feeding
Feeding is not typically required when Japanese painted ferns are grown in fertile and humus-rich soil in the ground in a garden. An organic mulch replenished each spring is usually sufficient. Indoors, however, feeding is often required to keep ferns happy and healthy.
Feed these ferns with compost tea or another organic liquid plant feed every month or so throughout the spring and summer. But take care not to over-fertilize as this can do more harm than good.
Winter Care
This is a deciduous fern and the fronds will naturally die back for the winter. The plant will enter a period of dormancy through the coldest part of the year and then develop new growth each spring.
It is best to allow the plant to die back naturally and then trim off dead foliage in the early spring, taking care not to damage the new fronds emerging at this time.
Remember to cut back on watering and stop feeding during the winter months when these ferns are in their dormant phase, before resuming these things in the spring when growth resumes once more.
Common Problems
Japanese painted ferns are not particularly prone to pest problems. When problems arise, these are more likely to be due to deficiencies in the placement or care of the plants.
Browning of fronds is sometimes natural, for example, but can sometimes be due to a watering problem, or too much sun. Fungal issues or root rot can arise due to over-watering or poor drainage.
Repotting
Japanese ferns can be potted up to slightly larger containers when they become root bound in their present containers and you can see roots escaping from the holes at the base of the pot. These are fairly slow-growing ferns and so this is not a job you will have to do too frequently.
These ferns should reach around 18 inches or so tall, and in diameter, at maturity. If you wish to keep them smaller, you can divide the plants and separate the divisions into their own individual pots.
