Soil & potting mix
Best soil for Walking Fern (Asplenium rhizophyllum)
Also called Walking Fern, Walking Spleenwort.
More about walking fern
About Walking Fern
Asplenium rhizophyllum · also called Walking Fern, Walking Spleenwort · houseplant
Walking fern is a small evergreen spleenwort with long, tapering, arrow-shaped fronds that root where their tips touch soil, forming new plantlets that appear to walk across the ground. Native to shaded limestone rocks in eastern North America, it thrives in cool, humid, low-light terrariums on moist, alkaline, gritty substrate and stays under 15 cm tall.
Preferred mix: Gritty, alkaline, sharply draining mix
Watch for — Browning, crispy frond tips: Caused by low humidity or letting the substrate dry out. Raise humidity in a terrarium and keep the rooting medium evenly moist.
Why walking fern needs this mix
Walking Fern hates drying out, so it wants a mix that stays evenly moist — but it still needs perlite so "moist" never tips into "waterlogged".
- Walking Fern comes from damp, shaded forest floors and has fine roots that scorch and brown the moment the rootball dries — the mix has to hold a steady reserve.
- Coir and compost give that reserve, while perlite keeps enough air that the constantly-moist mix does not turn anaerobic.
- Even moisture also keeps its thin leaves from crisping at the edges, which is this plant’s most visible stress signal.
For the full picture on what makes up a good mix, see our guide to the main types of soil and potting media — it explains why each ingredient above behaves the way it does.
What goes wrong with the wrong mix
The wrong soil is one of the most common reasons walking fern struggles, and the damage often shows up weeks later as a watering problem. For this species specifically:
- A free-draining, gritty mix dries too fast for walking fern — you get crispy brown edges and frond or leaf drop within days of one missed watering.
- A pure, airless peat mix swings the other way: it holds water but suffocates the fine roots and rots the crown.
- Letting the mix dry to the point it shrinks from the pot is very hard to re-wet evenly and stresses the plant badly.
Using a sharp, fast-draining "houseplant" or cactus-leaning mix that lets walking fern dry out. It needs a moisture-retentive but still airy blend.
pH — does it matter for walking fern?
Walking Fern prefers a slightly acidic mix (around pH 5.5-6.5); a peat-free compost-and-coir blend sits there naturally, so routine pH testing is unnecessary.
If you want to check or adjust it, the soil pH guide walks through testing and the safe ways to nudge a mix more acidic or more alkaline.
DIY mix vs a bagged one
A good peat-free houseplant compost works for walking fern straight from the bag if you mix in some perlite for air. The DIY ratio above gives a more reliable moisture-to-air balance.
Drainage and the pot
Use a pot with a drainage hole but a less-porous material (plastic or glazed) so it does not dry too fast. Bottom-watering keeps the mix evenly moist without sogging the crown.
Peat-free mixes slump and compact as they hold moisture, so refresh walking fern's mix every 12-18 months to keep air in the rootball even if the pot size is unchanged. When the time comes, our repotting guide for walking fern covers the timing and technique step by step.
Walking Fern soil — frequently asked questions
What is the best soil mix for walking fern?
3 parts peat-free houseplant compost : 1 part coco coir : 1 part perlite. Walking Fern comes from damp, shaded forest floors and has fine roots that scorch and brown the moment the rootball dries — the mix has to hold a steady reserve.
Can I use normal potting soil for walking fern?
A free-draining, gritty mix dries too fast for walking fern — you get crispy brown edges and frond or leaf drop within days of one missed watering. A good peat-free houseplant compost works for walking fern straight from the bag if you mix in some perlite for air. The DIY ratio above gives a more reliable moisture-to-air balance.
Does walking fern need a special pH?
Walking Fern prefers a slightly acidic mix (around pH 5.5-6.5); a peat-free compost-and-coir blend sits there naturally, so routine pH testing is unnecessary.
Should I buy a bagged mix or make my own for walking fern?
A good peat-free houseplant compost works for walking fern straight from the bag if you mix in some perlite for air. The DIY ratio above gives a more reliable moisture-to-air balance.
How often should I refresh the soil for walking fern?
Peat-free mixes slump and compact as they hold moisture, so refresh walking fern's mix every 12-18 months to keep air in the rootball even if the pot size is unchanged. Use a pot with a drainage hole but a less-porous material (plastic or glazed) so it does not dry too fast. Bottom-watering keeps the mix evenly moist without sogging the crown.
Keep reading
- Walking Fern care — the full brief (light, water, humidity, problems, pet safety)
- How often to water walking fern — the schedule the mix feeds into
- Repotting walking fern — when and how to refresh the mix
- Soil pH guide — test it and adjust it safely
- Underwatered plant — signs and how to rehydrate it
- Why is my plant wilting? Wet vs dry diagnosis
- Should I water my plant? The simple check first
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