Moss is the natural turf of any miniature world. At a small scale its fine texture reads convincingly as rolling lawn, woodland floor or hillside, which is why it is the heart of fairy gardens and model landscapes alike, and a lovely project to build with children.
Moss as the lawn of a tiny world
The trick of a miniature landscape is scale, and moss gets the scale right where grass or ordinary plants would tower absurdly over a little scene. A cushion moss becomes a hill, a flat carpet moss becomes a meadow, and a fern moss becomes a stand of miniature trees. Around those, small stones turn into boulders and a saucer of water into a pond, so the moss does most of the work of suggesting a whole landscape. Mixing two or three kinds of moss deepens the illusion, since the change of texture between a tight cushion and a loose feathery carpet does the same job as the shift from open meadow to wooded bank in a full-size view.
Why moss holds up where bedding plants fail
Part of the appeal is that moss actually survives the treatment a little dish garden hands out. It has no roots to rot in shallow, poorly drained soil, and it does not mind being confined, since it feeds from the air and rain rather than from the ground beneath. It takes in water across its whole surface, so a light misting keeps it going where a rooted seedling would wilt. And because it is poikilohydric, drying out and reviving with the moisture around it, a fairy garden left unwatered for a week tends to pause rather than perish, then greens up again the moment someone remembers to spray it. Few living materials are so forgiving of a child's uneven attention.
Choosing the container
A shallow bowl, an old drawer, a wooden tray or a large saucer all work, and a clear glass dish or a lidded jar holds humidity best and keeps the moss greener with less effort. Whatever you use wants a little drainage material in the base if it is open, since moss dislikes standing water, and bright but indirect light. A covered container behaves like a terrarium and is the easiest to keep alive indoors.
Building the scene
Lay a thin base of free-draining substrate, then press in your moss as the ground layer, butting the pieces together and using cushions for high ground and carpets for the flats. Add the features, a pebble path, a piece of bark, a small ornament or a fairy door, before the moss knits in, so it settles around them naturally. Keep the planting sparse and let the moss carry the composition; an overcrowded scene loses the calm that makes these little worlds appealing.
Keeping it alive
Mist it to keep the moss damp, stand it out of direct sun, and use rainwater if your tap is hard. In an open dish it will need misting every few days; under glass it can go a fortnight or more between sprays. Treat it as you would a terrarium, and the green lawn of your tiny world will hold for a long time, which is part of what makes it such a rewarding thing to make with a child.