Fertilising guide
How to fertilise Erect Moss Fern (Selaginella erythropus)— schedule & NPK
Also called Red Selaginella, Ruby Spikemoss, Erect Spikemoss.
More about erect moss fern
About Erect Moss Fern
Selaginella erythropus · also called Red Selaginella, Ruby Spikemoss · houseplant
Selaginella erythropus is a striking spikemoss from tropical America with reddish-tinged undersides on its branching fronds. It forms neat, upright clumps ideal for terrariums and humid displays. Like most Selaginella, it carries no known toxicity and is not listed as harmful by the ASPCA.
Growth habit: Upright, branching clump-forming perennial spikemoss
What fertiliser erect moss fern actually wants — and why
Erect Moss Fern is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula.
For the language behind the three numbers on the bottle — what nitrogen, phosphorus and potassium each do — see the NPK ratio explained entry. The short version for erect moss fern: match the feed to the job the plant is doing right now, not to a generic “plant food” on the shelf.
How often to feed erect moss fern, and which months
Feeding only earns its keep while the plant is in active growth and can use the nutrients — pour feed into a dormant or low-light plant and it simply builds up as root-burning salt. For erect moss fern:
Feed once a month during spring and summer with a balanced liquid fertiliser at quarter strength. Stop feeding entirely in autumn and winter when growth slows. Treat that as once a month between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
The dormant-season rule matters more than the exact interval: skip feeding entirely when erect moss fern is resting. For the wider context on indoor feeding rhythms across the seasons, the houseplant fertiliser schedule walks through the year month by month.
What strength to mix for erect moss fern
Half strength is the safe default for erect moss fern — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
Feeding always goes onto already-damp soil, never dry roots — water erect moss fern first if the soil is dry, then apply the diluted feed. The companion question is when to water at all, covered in the erect moss fern watering schedule.
Signs you are over-feeding erect moss fern
Over-feeding is far more common — and more damaging — than under-feeding for most plants. The classic tells for erect moss fern:
- Brown, crispy leaf tips and edges with no sign of underwatering.
- A white, crusty salt deposit on the soil surface or pot rim.
- Weak, pale, stretched new growth that flops.
- Lower leaves yellow and drop while the soil is correctly watered.
Signs you are under-feeding erect moss fern
- Uniformly pale or yellow-green leaves, oldest first.
- Noticeably small new leaves and stalled growth in good light and season.
- A generally tired, lacklustre look despite correct watering and light.
If the symptoms point at watering, light or roots rather than nutrition, the full erect moss fern care brief covers soil, humidity and the common problems for this species.
Flushing and leaching the salts
Flush the pot of erect moss fern with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Organic vs synthetic feeds for erect moss fern
Organic options
A diluted seaweed or worm-casting feed, or fish emulsion if you can tolerate the smell indoors. UK: Westland or Baby Bio Organic, dilute seaweed; US: Espoma Indoor! or Neptune's Harvest fish & seaweed. Slow, gentle and hard to overdo.
Synthetic / liquid feeds
A general-purpose houseplant liquid at half strength — UK: Baby Bio, Westland Houseplant Feed or Phostrogen; US: Miracle-Gro Indoor Plant Food or Schultz. Convenient and fast-acting; the only risk is overdoing it.
Brand names are examples, not endorsements, and UK and US ranges differ — check the label’s own NPK and dilution rate, since formulations change.
Fertilising erect moss fern — frequently asked questions
What fertiliser does erect moss fern need?
A balanced general houseplant feed (roughly even N-P-K) is exactly right — it is grown for foliage, so steady, moderate nitrogen for healthy leaves is the goal, not a bloom or root formula. Erect Moss Fern is an easy, light foliage feeder — a half-strength balanced liquid feed through the growing months keeps it green without forcing weak, sappy growth.
How often should I feed erect moss fern?
Feed once a month during spring and summer with a balanced liquid fertiliser at quarter strength. Stop feeding entirely in autumn and winter when growth slows. Feed once a month during spring and summer with a balanced liquid fertiliser at quarter strength. Stop feeding entirely in autumn and winter when growth slows. Treat that as once a month between spring through early autumn (roughly March to September); ease off in autumn and stop entirely in the low light of winter.
What strength of feed for erect moss fern?
Half strength is the safe default for erect moss fern — houseplant feeds are formulated strong, and the diluted dose is gentler on the roots while still ample for foliage.
What does over-feeding erect moss fern look like?
Brown, crispy leaf tips and edges with no sign of underwatering. A white, crusty salt deposit on the soil surface or pot rim. Weak, pale, stretched new growth that flops. Lower leaves yellow and drop while the soil is correctly watered. Feeding erect moss fern year-round on a fixed schedule, including dark winter months, is the most common mistake — it cannot use the nutrients in low light and the surplus simply burns the roots and crusts the soil.
Should I flush the soil of erect moss fern?
Flush the pot of erect moss fern with plain water until it runs freely from the base every couple of months in the feeding season — it washes out the fertiliser salts that cause brown tips.
Keep reading
- Erect Moss Fern care — the full brief (light, soil, humidity, problems, pet safety)
- How often to water erect moss fern — the watering schedule
- The houseplant fertiliser schedule — feeding through the year
- NPK ratio explained — what the three numbers on the bottle mean
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- All 11687 fertilising guides in the Growli library