Soil & potting mix
Best soil for Spike Moss (Selaginella kraussiana)
Also called Spike moss, Krauss' clubmoss, Krauss' spikemoss, African clubmoss, Japanese moss, Trailing Irish moss, Spreading club moss.
More about spike moss
About Spike Moss
Selaginella kraussiana · also called Spike moss, Krauss' clubmoss · houseplant
Spike moss (Selaginella kraussiana) is a low, creeping fern relative grown for its fine, feathery emerald foliage and mat-forming habit, ideal for terrariums. It demands constant moisture, very high humidity, and shade from direct sun. The ASPCA lists it as non-toxic to dogs, cats, and horses, making it pet-safe.
Preferred mix: Rich, humus-heavy, moisture-retentive mix with good drainage
Watch for — Brown, shrivelled or crispy foliage: Almost always caused by low humidity or the soil drying out. Raise humidity to 70%+ (a terrarium, humidifier, or pebble tray) and keep the mix constantly damp.
Why spike moss needs this mix
Spike Moss hates drying out, so it wants a mix that stays evenly moist — but it still needs perlite so "moist" never tips into "waterlogged".
- Spike Moss 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 spike moss 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 spike moss — 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 spike moss dry out. It needs a moisture-retentive but still airy blend.
pH — does it matter for spike moss?
Spike Moss 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 spike moss 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 spike moss'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 spike moss covers the timing and technique step by step.
Spike Moss soil — frequently asked questions
What is the best soil mix for spike moss?
3 parts peat-free houseplant compost : 1 part coco coir : 1 part perlite. Spike Moss 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 spike moss?
A free-draining, gritty mix dries too fast for spike moss — you get crispy brown edges and frond or leaf drop within days of one missed watering. A good peat-free houseplant compost works for spike moss 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 spike moss need a special pH?
Spike Moss 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 spike moss?
A good peat-free houseplant compost works for spike moss 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 spike moss?
Peat-free mixes slump and compact as they hold moisture, so refresh spike moss'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
- Spike Moss care — the full brief (light, water, humidity, problems, pet safety)
- How often to water spike moss — the schedule the mix feeds into
- Repotting spike moss — 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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