Glow-in-the-dark terrarium: how to make it glow at night

A glow-in-the-dark terrarium is an ordinary terrarium, with plants and moss, where you place figurines that glow in the dark. The figurines charge in daylight or under a lamp. When the room is dark, they give off a soft glow that fades little by little. The plants themselves do not glow.

How phosphorescence works

Some materials absorb light and release it later. The Larousse encyclopedia separates two cases. When the light is released straight away, it is fluorescence. When there is a delay between absorption and emission, it is phosphorescence.

This delay is what makes a figurine glow after you switch off the lamp. The material stores part of the light it receives, then releases it slowly. This is also why the glow fades: the store runs out.

The manufacturer of our figurines does not give a glow time. It does not say which pigment it uses either. It only says that the effect is strongest after a few hours of bright light.

Glow-in-the-dark or neon: do not confuse them

The two can look alike, but the effect is not the same.

• Glow-in-the-dark: the figurine glows in the dark, after charging in light.
• Neon: the figurine has very bright colors in full light. It does not necessarily glow in the dark.

Our set of neon mushrooms is an example. Its ten mushrooms, about 1.5 cm tall, are painted purple, pink, blue, yellow and red. Its product page does not list a glow-in-the-dark effect. It is a good choice for color by day, not for a glow at night.

Before you buy, look for the line "Effect: glow-in-the-dark" on the product page of the set.

The sets that glow in the dark

Our glow-in-the-dark figurines fall into three families.

The woodland. Six mushrooms about 2 cm tall, in soft colors. They stay discreet by day, and create a fairy-tale mood at night.

The village. Two houses of different shapes and two small inhabitants, 3 to 5 cm tall, in green, blue and white. These are the largest pieces in this guide: you can see them from across the room.

The characters. Several sets, for a lighter touch:

• six characters about 3 cm tall, one in each color;
• seven bath ducks about 2 cm tall, in glow-in-the-dark plastic;
• blue or green PlantHeroes about 3 cm tall, in sets of ten, or six blue ghosts. They stand up by themselves.

The minis. Fourteen different figurines about 1 cm tall, in glow-in-the-dark plastic. Their small size suits small terrariums.

Charge the figurines without harming the plants

The figurines like bright light. Terrarium plants, on the other hand, suffer in direct sun. The RHS says to keep terrariums out of direct summer sun and away from heat sources. Penn State Extension goes further: a terrarium must not sit in direct sun, which makes it overheat.

Here are three ways to have both:

1. Charge before you place them. Leave the figurines on a windowsill for a few hours, outside the terrarium. Then place them with tweezers.
2. Use a lamp. The manufacturer says that lamplight also charges the figurines. A lamp switched on near the glass, a few hours before nightfall, recharges the figurines without putting the plants in the sun.
3. Make use of daylight. A terrarium in bright, indirect light already charges its figurines a little. The glow will be weaker than after charging in full light.

Do not move the terrarium into the sun to recharge it. Direct sun makes the glass overheat, and the plants suffer.

The glow does not replace light

A glowing figurine does not feed the plants. Its glow is far too weak. According to the RHS, terrarium plants need bright, indirect light for at least six hours a day.

The RHS also says that ordinary household lamps do not suit plants. So a desk lamp can charge the figurines without giving the plants enough light. If your terrarium lacks light, our guide to terrarium lighting explains how to choose a grow light.

Build a scene for the night

A glow-in-the-dark scene is meant to be seen in a dark room. A few simple rules:

• Place the glowing pieces at the front, near the glass but not touching it. Moss and plants can hide a glow placed at the back.
• Group them in twos or threes. A small group shows up better than a single piece.
• Mix them with figurines that do not glow. By day, the scene stays coherent. At night, only a few points light up.
• Use only a few pieces. An overcrowded terrarium loses its landscape.

To build the rest of the scene, see our guide to terrarium figurines. For winter, the set of glow-in-the-dark houses in the miniature Christmas village also glows at night.

Material and care

Our glow-in-the-dark figurines are made of plastic or synthetic material. For most sets, the supplier says they handle condensation and contact with damp moss. A dry paintbrush is enough to clean them.

These are decorative objects, not toys. The pieces are small: keep them out of reach of children under 3. Health Canada gives a simple test: an object that fits through a toilet paper roll is too small for them.

In short

1. In a glow-in-the-dark terrarium, the figurines glow, not the plants.
2. A phosphorescent material releases light after a delay, then its glow fades.
3. Neon does not mean glow-in-the-dark: check the "Effect" line on the product page.
4. Charge the figurines outside the terrarium or under a lamp, never the terrarium in the sun.
5. The glow does not feed the plants: keep them in bright, indirect light.

Sources

• Luminescence, encyclopédie Larousse (in French)
• Bottle gardens and terrariums, RHS
• Creating a Closed Terrarium, Penn State Extension
• Toy safety tips, Health Canada
• Manufacturer data sheets (contents, size, material and glow-in-the-dark effect of each set)