Gather Your Materials

An engineer's shopping list

Every good build starts with the right parts. Your humidity tent needs only a few, and none of them are fancy or expensive. Let's meet each one and learn the job it does. Understanding why each part is on the list will make you a smarter builder.

Wash your hands, grab a notebook, and let's take inventory.

The tote: your see-through room

The body of your chamber is a clear plastic tote with a lid — the kind used for storing toys or clothes. Clear plastic matters for two reasons: it traps the damp air inside, and it lets you see and lightly light your mushrooms without opening the lid.

A tote of about 50 to 70 quarts (roughly 45 to 66 litres) gives one or two grow kits plenty of room. You want space for the mushrooms to grow tall without touching the walls.

Perlite: the humidity sponge

Here is the star of the show. Perlite is a natural volcanic glass that has been heated until it puffs up like popcorn, expanding many times its original size. The puffing leaves it full of tiny air pockets, nooks, and crannies.

Those pockets are what make perlite so useful. When you moisten perlite, it holds water on all that bumpy surface. The water then slowly evaporates into the box, filling the air with the humidity your mushrooms crave. A layer of damp perlite is like a slow, gentle fog machine with no moving parts.

Buy coarse horticultural perlite from a garden shop. You will need a bag large enough for a 2 to 4 inch (5 to 10 cm) layer in the bottom of your tote.

The hygrometer: your measuring tool

You cannot hold a target you cannot measure. A hygrometer is a small instrument that measures relative humidity and shows it as a percentage on a dial or screen. Many cheap ones also show the temperature.

This is the tool that turns your project into real science. Instead of guessing, you will read the number and adjust. Choose one that can read all the way up to at least 90%, so it does not max out inside your damp chamber.

Also handy

• A spray bottle of clean water for misting.

• Tape or a marker to plan your holes (coming next lesson).

• A drill with a 1/4 inch bit — but remember, only a grown-up uses the drill.

Perlite can be dusty, and the fine dust is not nice to breathe. When you open the bag, have a grown-up help, do it outside or in a garage, and dampen the perlite to keep the dust down. And the usual mushroom rule always holds: we only grow known-safe kit mushrooms, and we never pick or eat wild ones.

You have your parts. Next, we drill the holes that let your fungus breathe.