Watering schedule

How often to water Spike Moss (Selaginella kraussiana) — the schedule

Also called Spike moss, Krauss' clubmoss, Krauss' spikemoss, African clubmoss, Japanese moss, Trailing Irish moss, Spreading club moss.

More about spike moss

Watering at a glance

Base rhythm	Keep evenly moist at all times; typically water every 2-4 days so the soil never dries out
Spring / summer	Spring and summer: keep the soil evenly, lightly moist at all times — check every 2-4 days and water before the surface dries.
Autumn	Autumn: growth slows a little, so check every few days rather than daily, but never let the rootball dry out.
Winter	Winter: still keep barely moist — a fern that dries out in a centrally heated room crisps up within a day or two.
Light	Medium indirect light (a couple of metres from a window)

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.

Ideal humidity: 70% or higher

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.

The watering schedule, season by season

Spike Moss is a moisture lover — it never wants to dry out fully, and dry air sheds fronds faster than anything. The base rhythm for spike moss is keep evenly moist at all times; typically water every 2-4 days so the soil never dries out, but the real interval moves with the season, the light and the pot — so treat the figures below as a starting point and always confirm with the plant itself.

Spring & summer (active growth): Spring and summer: keep the soil evenly, lightly moist at all times — check every 2-4 days and water before the surface dries.
Autumn (slowing down): Autumn: growth slows a little, so check every few days rather than daily, but never let the rootball dry out.
Winter (rest / dormancy): Winter: still keep barely moist — a fern that dries out in a centrally heated room crisps up within a day or two.

The soil must stay consistently damp but never waterlogged, as standing water leads to root rot. Never let it dry out, even briefly. Use room-temperature rainwater, distilled, or filtered water where possible, since the shallow roots are sensitive to cold-water shock and mineral build-up.

Want this turned into a live reminder that adjusts to your home and the weather? The Growli watering calculator takes your pot size, light and season and returns a starting interval for spike moss in seconds.

How to tell spike moss needs water

A calendar is the worst way to water spike moss. Check the plant and the soil instead — for this species, look for these signals in order:

The very top of the compost feels dry to the touch (do not wait longer than this).
Fronds start to look slightly limp or lose their fresh sheen.
Frond tips begin to pale or curl before going crispy.

The most reliable single check is the first one on that list. When two signals agree, water; when they disagree, wait a day and look again — under-watering spike moss for a day is almost always safer than over-watering it.

Overwatering vs underwatering spike moss

The two failure modes can look alike at a glance, so check the soil weight and wetness before you decide. For spike moss specifically:

Signs you are overwatering

Yellowing, mushy crowns and a sour-smelling pot — even a moisture lover rots if waterlogged.
Blackened frond bases at soil level.
Fungus gnats thriving in permanently saturated compost.

Signs you are underwatering

Crispy brown frond tips and edges — the classic dry-air / dry-soil fern signal.
Wholesale frond drop after the rootball shrinks away from the pot sides.
A faded, washed-out look across the whole plant.

Letting spike moss dry out completely even once browns the fronds irreversibly — they do not green back up. Consistency beats volume.

Water quality notes

Use rainwater or filtered water for spike moss where you can — ferns are sensitive to chlorine and tap-water minerals, which contribute to brown tips.

Seasonal and environmental adjusters

Every figure above shifts with the conditions in your home. For spike moss, the levers that matter most are:

Humidity and watering are linked — at 60%+ humidity the soil stays moist longer and you water less.
A plastic or glazed pot holds moisture better than terracotta, which is an advantage for a thirsty fern.
Bottom-watering or a pebble tray keeps moisture even and avoids wetting the crown.

Pot choice is part of this too — work out the right size with the pot size calculator, since a pot that is too big stays wet long enough to rot the roots of spike moss.

Spike Moss watering — frequently asked questions

How often should I water spike moss?

Water spike moss keep evenly moist at all times; typically water every 2-4 days so the soil never dries out. Spring and summer: keep the soil evenly, lightly moist at all times — check every 2-4 days and water before the surface dries. Winter: still keep barely moist — a fern that dries out in a centrally heated room crisps up within a day or two.

How do I know when spike moss needs water?

The very top of the compost feels dry to the touch (do not wait longer than this). Fronds start to look slightly limp or lose their fresh sheen. Frond tips begin to pale or curl before going crispy. The single most reliable test for spike moss is the first signal on that list — checking the soil or the plant directly always beats watering by the calendar.

What does an overwatered spike moss look like?

Yellowing, mushy crowns and a sour-smelling pot — even a moisture lover rots if waterlogged. Blackened frond bases at soil level. Fungus gnats thriving in permanently saturated compost. Letting spike moss dry out completely even once browns the fronds irreversibly — they do not green back up. Consistency beats volume.

What are the signs of an underwatered spike moss?

Crispy brown frond tips and edges — the classic dry-air / dry-soil fern signal. Wholesale frond drop after the rootball shrinks away from the pot sides. A faded, washed-out look across the whole plant.

Can I use tap water on spike moss?