Button fern, Pellaea Rotundifolia, is an eye-catching fern from New Zealand. It can survive cold temperatures but cannot survive a frost, and can be a good candidate for growing indoors in cooler temperate climates.
If you have had trouble growing ferns indoors, then the unfussy button fern could be a good choice for you.
What is Button Fern?
Button fern is an evergreen fern also known as New Zealand cliff brake, round-leaved fern, or Tarawera. It is a compact plant that won’t take up a lot of space indoors.
It forms neat, flat rosettes of pinnate fronds that grow around 25cm long. Each of those fronds is made up of rounded leaflets with a dark green hue, borne on brown stems with pinkish scales.
This species has been given an award of garden merit (AGM) by the British Horticultural Society (RHS).
Do not confuse the button fern with the entirely unrelated plant known as the lemon button fern, Nephrolepsis cordifolia, which is a small relative of the Boston fern. These are both ferns, but have few similarities beyond that and look rather different from one another.
Where to Grow Button Fern
Button ferns can be grown outside year-round where temperatures do not drop below freezing. But they can also be grown indoors as long as they are provided with the right growing conditions.
The key things to think about are light, temperatures and humidity, and the growing medium in which this fern should be grown.
When growing outdoors, button ferns can be grown in a position in full sun or in partial shade. Indoors, they should be placed somewhere with bright but indirect or filtered light.
It is important to avoid placing button ferns in a spot where they will receive too much direct sun during the hottest times. A north or east-facing windowsill might be ideal.
Temperature & Humidity Requirements
These New Zealand ferns are not as fussy as some other ferns like maidenhair ferns for example.
They can cope with a wide temperature range, though 16 to 24 degrees Celsius is ideal. It is best to maintain temperatures that are more on the stable side, without sudden draughts or extreme temperature fluctuations.
Make sure that you do not place this fern too close to heat sources such as radiators, ovens, or stoves. And avoid a position where the plant may be exposed to chilly draughts.
Ferns all like relatively humid conditions. But button ferns are more tolerant of lower humidity. Though they don’t need conditions to be as humid as some others, they still prefer humidity to be over 50%.
To raise the humidity, group houseplants together, mist plants regularly, and/or place pots on trays of water and pebbles from which water can evaporate. A steamy bathroom can be a good place for this fern, as long as there is enough natural light.
Soil/ Growing Medium
Button ferns need a moist but free-draining, acidic soil or growing medium. Ideally, this medium should be moderately fertile.
When growing in pots indoors, a peat-free, ericaceous potting mix should be used. An ericaceous potting mix is one specially formulated for use with acid-loving plants. It must drain freely to avoid issues with waterlogging.
Planting Button Fern
Button ferns can be grown from spores or propagated by division. These plants can also simply be purchased as potted specimens. Once purchased, it is best to pot them up into more long-lasting containers rather than keeping them in nursery pots.
When planting button ferns into a container, make sure that you choose a container just a little larger all around than the existing root system. Since these plants have a fairly shallow root system, do not choose too deep a pot.
Make sure that in addition to choosing a moist but free-draining growing medium, you also ensure that the container has sufficient drainage holes at the base.
Caring for Button Fern
Button ferns are not challenging to grow indoors. Even the least green-fingered should be able to care for them without too much difficulty. Watering is of course the main job to think about when growing button ferns in your home.
Water to keep the button fern’s growing medium just moist at all times. But make sure that it is just moist and not waterlogged. Waterlogged conditions are one of the worst things for these ferns and can lead to root rot.
In fact, it is best to err on the side of caution, since button ferns can cope better than most other ferns when the growing medium dries out a little. Just aim to water once more whenever the top few centimeters of the growing medium in the container feel dry.
Throughout the spring and summer months, the best results can be achieved by feeding your button fern with a dilute compost tea or other balanced, organic liquid plant feed every month or so through the growing season.
The leaves of this fern will naturally die back for the dormant period in winter. Old leaves can simply be removed as they die back and the rest of the plant should keep green leaves throughout even the coldest and darkest part of the year.
Most of the problems encountered when growing button ferns are related to environmental issues, or are caused by incorrect care.
Often, issues arise due to light, temperature, humidity, or water. Too much water, and waterlogging which leads to root rot are likely to be among the most serious common problems you may encounter if you water too much, or if drainage is poor.
Button ferns will not grow very quickly and remain a manageable size. So they will not need to be repotted too frequently.
But look out for roots appearing on the surface of the growing medium, or protruding from holes at the base of a pot. These signs that a plant is root-bound mean that it is time to choose a new container, just slightly larger than the old one, and to repot your button fern.