Organic Oyster Mushroom Kit — Growing Guide & Support

User Guide and Support

Organic Oyster Mushroom Kit

Your kit is alive and ready to produce mushrooms. Open the window, place it in the right spot, and keep it moist—the first oyster mushrooms should appear soon.

🍄 Ready to Grow 🌱 Certified organic 🇧🇪 Produced in Belgium 👨🌾 No experience necessary

Ideal Conditions

🌡️ 10 to 20 °C Temperature
💧 Damp Not soggy
☀️ Indirect light No direct sunlight
🌬️ Fresh air No drafts

Get Started with the Kit in 4 Steps

1

Open the window

Detach the pre-cut section from the box. Using a clean knife, cut a cross in the plastic bag, but only at this opening.

Do not remove the bag completely: it protects the growing medium and helps it retain moisture.

2

Choose the right location

Place the kit in a well-lit room, away from direct sunlight, ideally at a temperature between 10 and 20 °C. A kitchen, a cool room, a well-lit garage, or a basement with a light source would be suitable.

Avoid radiators, stoves, windows in direct sunlight, and drafts.

3

Keep the opening moist

Spray clean water into the opening once or twice a day. The goal is to maintain a humid environment without letting the water run off or soaking the kit.

In a very dry room, you can spray a little more often around the opening.

4

Watch the plant grow

Small buds should appear as the cluster opens. From that point on, the oyster mushrooms grow very quickly: check on them every day and continue to maintain good humidity around the cluster.

Caution: Do not spray heavily directly onto young mushrooms. A light mist around the opening is sufficient. Standing water can cause spots and deformities.

What can you expect?

Days 1–7: The mycelium adapts to its new conditions. Continue to moisten the opening, even if nothing is visible yet.
Days 5 through 12: Small gray or white buds usually begin to appear. They will then grow very quickly.
Days 8 through 15: The cluster may be ready for harvest. The timeframe varies depending on temperature, humidity, and the maturity of the kit.
Good to know: Mushrooms don't always follow a strict schedule. A cooler room generally slows down growth but can produce denser mushrooms. 

When and how should you harvest?

The Right Time

Harvest when the caps are fully formed but before their edges curl up too much.

The Right Thing to Do

Grasp the entire cluster at its base and gently twist it. Avoid picking the mushrooms one by one.

After the harvest

Remove any remaining parts of the plant that may be left in the opening to prepare the kit for its next growth cycle.

Young oyster mushrooms are generally more tender and keep better. Don't wait until the caps become completely flat or start to dry out at the edges.

Get a second one harvest

1

Let the kit rest

After the first harvest, remove any remaining mushrooms and let the kit rest for about one to two weeks. Continue to keep it away from heat and dryness.

2

Rehydrate the growing medium

Take the bag out of the box and soak it in cold water overnight. Use a clean object to keep it submerged, then let it drain thoroughly.

3

Reinstall and restart the kit

Put the bag back in its box with the opening facing the window, then resume misting. Exposing the plant to cold temperatures during rehydration also helps stimulate new growth.

The kit can produce several harvests of mushrooms. The first harvest is usually the most abundant, and subsequent harvests are often smaller.

Set the kit aside before you begin

Not ready to start your grow yet? Keep the kit sealed in a cool place, ideally in the refrigerator or at a temperature below 10 °C.

For best results, however, we recommend starting it as soon as possible. Never place the kit in the freezer.

If mushrooms are already starting to grow in the box, set up the kit immediately and place the opening in front of the area where they are appearing.

Troubleshooting: What to Do If…

Nothing grows after 10 to 15 days

First, check the temperature, light, and humidity. The kit should not be placed near a radiator, in direct sunlight, or in a draft.

If it seems dry, remove the bag from the box, soak it in cold water overnight, drain it, and then put it back. This soaking rehydrates the substrate, and the exposure to cold can stimulate the fruiting.

The substrate turns brown around the opening

Localized browning usually indicates that the surface has dried out. Slightly increase the frequency of misting and move the kit away from heat sources or drafts.

If the block seems very dry, soak it thoroughly in cold water overnight.

Mushrooms have long stems and small caps

They're probably not getting enough fresh air. Ventilate the room more, or move the kit to a better-ventilated area—but avoid placing it in a drying draft.

The mushrooms dry out or become brittle

The air is probably too dry. Spray more frequently around the cluster and keep the kit away from heaters, direct sunlight, and drafts.

The mushrooms are very damp or have spots on them

Minimize direct spraying on the mushrooms and slightly improve air circulation. The opening should remain moist, but the oyster mushrooms should not be constantly wet.

A white powder appears under the hats

These are likely spores released by mature fungi. They are natural, but indicate that the harvest should ideally have been done a little earlier.

White down appears on the feet

This is generally mycelium, not mold. This phenomenon is common when humidity is high or there is insufficient ventilation.

A green, black, or orange discoloration appears

A bright discoloration accompanied by an unpleasant odor may indicate contamination. Isolate the kit from food and other cultures, avoid inhaling or spreading the spores, and then take photos before contacting us.

Storing and Cooking Oyster Mushrooms

After harvest, store the oyster mushrooms in the refrigerator in a paper bag or a container that allows the mushrooms to breathe slightly. They generally keep for 5 to 7 days.

To prepare them, cut off the firm base of the cluster, separate the mushrooms, and then sauté them in a pan until lightly browned. Avoid soaking them in water: a quick wipe with a brush or a damp cloth is usually sufficient.

Need help with your kit?

Please send us a photo of the kit, the opening, and the mushrooms, along with the start date and the room temperature. This information will help us advise you quickly.

Contact La Mycosphère

CERTISYS® is an officially recognized organic certification body in Belgium (BE-BIO-01).