---
title: Rock cap moss in a terrarium | Glass Jar Garden
description: Rock cap moss (Hedwigia) (Hedwigia ciliata): Grey-green mats with white tips from sunny rock. Needs to dry out between wettings. Needs light 8,000 to 60,000...
url: https://glassjar.garden/guide/moss/hedwigia-ciliata/
---

Moss

# Rock cap moss (Hedwigia)
Hedwigia ciliata

Demanding · Open jar only

Grey-green mats with white tips from sunny rock. Needs to dry out between wettings.

## What the simulation uses

- Light: 8,000 to 60,000 lux (The brightness it grows well in.)

- Humidity: 30 to 70 % RH (Air moisture it is happy in; below the lower end it dries out.)

- Temperature: 5 to 30 °C (Comfortable range; outside it growth slows.)

- Dies at: below -30 or above 48 °C (Days beyond these temperatures kill it.)

- Soil pH: 4 to 5.5 pH (Soil acidity it prefers.)

- Grows up: 0.03 cm/month (How fast it gains height in good conditions.)

- Spreads: 0.04 cm/month (How fast its edge creeps outwards.)

- Thickens: 0.3 %/month (How fast its cover fills in on its own ground.)

- Copes with wet: poor (How well it stands soggy soil; poor means rot comes quickly.)

- Copes with still air: poor (Sealed jars have still air; poor means grey mould finds it.)

- Copes with shade: poor (How well it holds on in dim light.)

- Copes with drying: excellent (How well it survives the jar drying out.)

- Water use: 0.04 ml/cm²/day (Water that evaporates off the cushion each day in room air.)

- Holds water: 0.2 ml/cm² (Water a cm² of moss soaks up and keeps.)

- Grows on: stone (Where it can take hold and spread. Moss that cannot grow on stone thins out there.)

## Care

- Day length: 10 to 14 h

- Substrate: Dry

## What kills it

- closed humid jar
- shade
- constant wetness

## Description
Wild colonies cover sunny, acid, exposed rock. A sealed humid jar, shade and constant wetness will all kill it, so it suits an open container in bright light. This one is tricky to keep.

Also called fringed hoar-moss, rock cap moss, white-tipped moss.

Estimated, where sources were thin: Dicranum fulvum has no fetched source (merged here as alias); growth rate; temp_c; humidity_rh_pct.

## Sources

- [nora.nerc.ac.uk/id/eprint/1131/1/BRYOATT.pdf](https://nora.nerc.ac.uk/id/eprint/1131/1/BRYOATT.pdf)
- [ohiomosslichen.org/moss-hedwigia-ciliata](https://www.ohiomosslichen.org/moss-hedwigia-ciliata/)

[Grow it in a jar](https://glassjar.garden/?guide=moss/hedwigia-ciliata)

[Red sphagnum](https://glassjar.garden/guide/moss/sphagnum-magellanicum/) · [Rough-stalked feather-moss](https://glassjar.garden/guide/moss/brachythecium-rutabulum/) · [All moss](https://glassjar.garden/guide/moss/)