Mature size & growth rate

How big does Cushion Moss Selaginella (Selaginella martensii) get?

Also called Martens Spikemoss, Trailing Selaginella, Variegated Selaginella.

More about cushion moss selaginella

About Cushion Moss Selaginella

Selaginella martensii · also called Martens Spikemoss, Trailing Selaginella · houseplant

Selaginella martensii is a popular terrarium and houseplant spikemoss from Mexico and Central America, known for its arching, branching stems and bright green foliage — variegated cultivars also exist. It performs best in high humidity. No known toxicity; not listed by ASPCA as harmful.

Mature size: 15-30 cm tall, spreading to 30-45 cm

Watch for — Leggy stems: Caused by insufficient light. Trim back long stems to encourage bushier growth and provide slightly brighter indirect light.

Indoor size vs how big it gets in the wild

Cushion Moss Selaginella stays fairly low but widens over time — it spreads into a bigger clump by offsets, runners or rhizomes rather than shooting upward. Indoors and in a pot, expect 15-30 cm tall, spreading to 30-45 cm. A pot, your light levels and a little pruning are what set the final size in a home, far more than the plant's theoretical potential.

Size here is about width, not height: the plant builds an ever-wider clump or sends out plantlets and runners while staying relatively short.

Growth rate and years to mature

Cushion Moss Selaginella is a moderate grower. Realistically, expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Its feeding profile backs this up: apply a balanced liquid fertiliser at quarter strength once a month during spring and summer. feed sparingly — selaginella has modest nutritional needs and excess fertiliser causes burnt tips.

Want this turned into the right next pot at the right moment? The pot size calculator and the cushion moss selaginella repotting guide cover when and how much to size up — pot size is one of the biggest levers on how fast cushion moss selaginella grows.

How to keep cushion moss selaginella smaller

You are not stuck with the maximum size. For cushion moss selaginella specifically, these are the levers, in order of impact:

Divide the clump every year or two — splitting cushion moss selaginella is the main way to control its spread and refresh it.
Remove runners, plantlets or offsets as they appear if you want it to stay a single tight clump.
Keep it slightly pot-bound; a snug pot naturally limits how wide the clump can get.

The keep-it-smaller method, step by step

Lift the whole plant. Slide cushion moss selaginella out of its pot in spring when the clump has filled it.
Split the clump. Tease or cut the rootball into two or more sections, each with healthy roots and growth.
Repot one division. Put a single division back in the original pot to reset it to a smaller size; pot or give away the rest.
Remove offsets as they form. Through the year, detach new runners or pups to stop it spreading again.

How to grow cushion moss selaginella bigger or faster

If you want it to fill the space sooner, push the conditions rather than hoping — for cushion moss selaginella the accelerators are:

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger.
Brighter light speeds up clump and offset production noticeably.
Leave plantlets and offsets attached and feed through the growing season for the fastest spread.

Light is almost always the ceiling. The cushion moss selaginella light requirements page covers exactly how bright a spot it needs to grow at its potential instead of stalling.

When cushion moss selaginella outgrows the room (or the pot)

"Too big" usually arrives as one of these signs for cushion moss selaginella:

The clump bulging over the pot rim or splitting the pot — the cue to divide, not to find a bigger room.
A dense centre that goes bare or tired while the edges keep spreading.
Runners or offsets escaping across the shelf or into neighbouring pots.

If it is the pot rather than the room, it is a repotting job, not a goodbye — see the cushion moss selaginella repotting guide. If you want more of this plant instead of a bigger one, the cushion moss selaginella propagation guide turns prunings into new plants.

Cushion Moss Selaginella size — frequently asked questions

How big does cushion moss selaginella get?

Cushion Moss Selaginella reaches 15-30 cm tall, spreading to 30-45 cm when grown indoors. Size here is about width, not height: the plant builds an ever-wider clump or sends out plantlets and runners while staying relatively short.

Is cushion moss selaginella slow or fast growing?

Cushion Moss Selaginella is a moderate grower. Expect three to six years to reach mature indoor size, gaining a steady amount each growing season. Cushion Moss Selaginella stays fairly low but widens over time — it spreads into a bigger clump by offsets, runners or rhizomes rather than shooting upward.

How long does cushion moss selaginella take to reach full size?

Roughly three to six years to reach mature indoor size, gaining a steady amount each growing season. Light, pot size and feeding move that timeline more than anything else.

How do I keep cushion moss selaginella smaller?

Divide the clump every year or two — splitting cushion moss selaginella is the main way to control its spread and refresh it. Remove runners, plantlets or offsets as they appear if you want it to stay a single tight clump. Keep it slightly pot-bound; a snug pot naturally limits how wide the clump can get.

How can I make cushion moss selaginella grow bigger or faster?

Give it a wider pot and let the clump fill it — width is exactly how this plant gets bigger. Brighter light speeds up clump and offset production noticeably. Leave plantlets and offsets attached and feed through the growing season for the fastest spread.