The Christmas fern, Polystichum acrostichoides, is one of the most common ferns to be found in eastern North America. It takes its common name from the fact that its evergreen fronds are still often green throughout the festive season.
What is Christmas Fern?
You can find Christmas fern in woodland and on the banks of streams from Nova Scotia west to Minnesota and also south all the way to Florida and Eastern Texas. This familiar fern is also cultivated in gardens. It is a fern that can do well in a range of environments – including indoors.
Though it will be more challenging to grow Christmas fern indoors than it is to grow it outside in the ground, you can enjoy its evergreen fronds throughout the year when you grow this fern as a houseplant in your home.
Where to Grow Christmas Fern
If you have a garden, it will often be easier to grow Christmas ferns there rather than indoors. But it is possible to meet the needs of these accommodating plants rather easily even when you are growing them inside your home.
Looking at light, temperature, and humidity allows you to understand more clearly where within your property these ferns can be grown.
Looking at where these ferns grow naturally in the wild will give you a clue about the light levels they prefer. These are woodland ferns, which thrive in the dappled shade of the forest floor.
We should aim to mimic those conditions indoors, by finding a spot in bright but indirect light, such as a north or east-facing windowsill, where these ferns should do well.
Interestingly, however, Christmas ferns are more tolerant of bright direct sun than some other ferns like maidenhair ferns for example.
They can cope with a sunny spot as long as they get enough moisture and are not allowed to dry out too much. But note that their lush green hue can desaturate and look washed out in too bright a spot, and growth may be stunted due to stress.
Temperature & Humidity Requirements
When growing Christmas ferns indoors, it is particularly important to get the temperatures and humidity levels right.
To remain happy and healthy, these ferns need temperatures that ideally remain between 10 and 21 degrees Celsius. So make sure you do not place them in a part of your home that gets too warm for them to thrive.
Humidity levels do not need to be sky-high as is ideal for some other ferns such as Boston ferns. But humidity of over 50% should be maintained.
If the humidity drops too low, raise it again by grouping houseplants together, misting, and/or placing pots on top of pebble-filled water saucers or trays.
Soil/ Growing Medium
Christmas ferns are moderately unfussy when it comes to the soil or growing medium in which they are placed.
They can tolerate a wide range of conditions. However, they do need free-draining conditions and cannot tolerate waterlogging, so a free-draining medium that remains moist but not wet is very important.
Planting Christmas Fern
Christmas ferns can be purchased as potted plants or propagated through root division in the early spring or by collecting and using the spores when these ripen in around October.
Choose a container for a Christmas fern that is large enough to accommodate the root system with just a little space to spare around them. Make sure you repot a Christmas fern at the same depth within the growing medium that it was at in its previous pot.
Caring for Christmas Fern
Caring for Christmas ferns indoors in containers does take a little more work than caring for those in your garden, where they will not need much attention at all. But as long as you get things right when it comes to watering, you should not go too far wrong.
When watering Christmas ferns in pots indoors, remember that you are aiming to keep the growing medium moist but not waterlogged at all times. Stick a finger into the pot and if the first few centimeters of the growing medium seem dry to the touch, it is time to water once more.
Each time you water, make sure you aim for the growing medium and try to avoid wetting the fronds where possible. Water deeply, but make sure that excess can flow away freely from the base of the pot so that waterlogging does not occur.
These ferns will need to be watered around once a week in most cases, through the spring and summer months, and a little less frequently during the colder part of the year. Though of course water needs will vary depending on the size and age of the plant and precise growing conditions.
In the ground, Christmas ferns will not need feeding at all, other than with the addition of an organic mulch each spring. But in pots, indoors, they may benefit from feeding with a weak compost tea solution or another organic liquid plant feed every month or so to maintain healthy growth through spring and summer.
Most of the problems you are likely to encounter when growing Christmas ferns relate to issues with the growing conditions or care.
For example, yellowing leaves are often a sign of a water-related issue or sun scorch. Dropping leaves can also indicate a water problem – often too little water is to blame.
One of the most common problems with these ferns is unfortunately crown rot. Christmas ferns can turn brown at the tips, which can be an early indicator that rot has set in.
Christmas ferns need only be repotted once the roots completely fill the current pot. You will not need to do this too often though because these ferns do not tend to grow too quickly.
These ferns can ultimately grow to around 2ft in height and spread. But plants can be divided to keep them smaller when they are grown indoors.
As long as you take good care of your Christmas fern you might keep it alive in your home for many years to come.