Soil & potting mix
Best soil for Spreading Spike Moss (Selaginella kraussiana)
Also called Krauss's Spike Moss, Mat Spikemoss, Trailing Spike Moss.
More about spreading spike moss
About Spreading Spike Moss
Selaginella kraussiana · also called Krauss's Spike Moss, Mat Spikemoss · houseplant
Spreading Spike Moss is a fast-growing, mat-forming spike moss native to the Azores, Canary Islands, and parts of Africa, widely naturalised in many warm-temperate regions. Its bright emerald-green, moss-like foliage spreads readily across moist soil. Ideal for terrariums and humid shelves. Not toxic to cats and dogs.
Preferred mix: Moisture-retentive, peat-free mix high in organic matter
Watch for — Root rot: While it needs constant moisture, waterlogged soil causes rot. Ensure the growing medium is moist but well-aerated, not sodden.
Why spreading spike moss needs this mix
Spreading 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".
- Spreading 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 spreading 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 spreading 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 spreading spike moss dry out. It needs a moisture-retentive but still airy blend.
pH — does it matter for spreading spike moss?
Spreading 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 spreading 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 spreading 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 spreading spike moss covers the timing and technique step by step.
Spreading Spike Moss soil — frequently asked questions
What is the best soil mix for spreading spike moss?
3 parts peat-free houseplant compost : 1 part coco coir : 1 part perlite. Spreading 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 spreading spike moss?
A free-draining, gritty mix dries too fast for spreading 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 spreading 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 spreading spike moss need a special pH?
Spreading 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 spreading spike moss?
A good peat-free houseplant compost works for spreading 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 spreading spike moss?
Peat-free mixes slump and compact as they hold moisture, so refresh spreading 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
- Spreading Spike Moss care — the full brief (light, water, humidity, problems, pet safety)
- How often to water spreading spike moss — the schedule the mix feeds into
- Repotting spreading 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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