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Freshmushroom® Grow Kit instructions

Freshmushroom® Grow Kit instructions

The complete 2026 guide to growing magic mushrooms with FreshMushrooms® XP grow kits — updated with the latest temperature and set-up recommendations.

What changed in 2026: The original FreshMushrooms PDF mentions a temperature range of 18–28°C. Based on years of customer feedback and our own testing we now recommend a tighter range of 21–24°C, with 23°C as the ideal target. Never let the temperature drop below 20°C — that is the most common reason kits fail to fruit properly. The full set of updated tips is described in detail below.

FreshMushrooms grow kit video instructions

Important: after the pinning process, put the grow bag straight up. Unfold the grow bag and stand it upright so the mushrooms have room to grow (see Step 6 below).

From box to harvest: the FreshMushrooms timeline

1
Set up
15 minutes

2
Colonise & pin
1–2 weeks

3
Fruit
1–2 weeks

4
Harvest & flush again
2–3 flushes

What is in the box

Every FreshMushrooms® XP grow kit contains:

1 × plastic grow box with fully colonised Psilocybe cubensis mycelium on a rye-based substrate (1200 cc)

1 × transparent grow bag with micro-perforations

2 × paperclips to seal the top of the bag

What you will need yourself:

Clean, draft-free spot indoors at room temperature

Some clean tap water for the cold shock (between flushes)

Optional but recommended: a thermo heating mat if your room is cooler than 20°C

Optional: a digital thermometer/hygrometer to monitor conditions

Before you start: storage and timing

Storage: FreshMushrooms kits are fresh, living products. Keep the kit in the refrigerator at 2–8°C until you are ready to use it. It can be stored this way for up to about 2 weeks. The colonised spawn pauses growth in the cold and resumes when it warms back to room temperature. Do not freeze.

Tip: Start your kit when you have a stable, warm room temperature (21–24°C). The whole process from set-up to first harvest takes about 2–4 weeks, so plan ahead if you are going away.

Step 1 Unpack the kit

Take FreshMushrooms grow kit out of the box — step 1 illustration

Take the grow kit, grow bag and paperclips out of the cardboard box. Keep the cardboard box — you will reuse it in Step 3 to block light from the sides.

Remove the lid from the plastic grow box. Rinse the lid under clean running tap water and store it — you will need it again after your first harvest for the cold shock (Step 6).

Work clean: Wash your hands and forearms thoroughly with disinfecting soap before handling the kit. Mould spores are everywhere and you want to minimise any chance of contamination. Sterile nitrile gloves are ideal but not required.

Step 2 Place the kit in the grow bag

Place FreshMushrooms grow kit in the grow bag — step 2 illustration

Lay the grow bag flat on a clean surface and slide the grow box (without lid) into it. The micro-perforation should point upwards — this is what lets fresh air in until the mushrooms start growing.

Slide the opening of the bag under the bottom of the box. The bag is now mostly closed and the kit has enough humidity inside. You do not need to seal it shut with the paperclips yet — air circulation is fine as-is.

Step 3 Choose the right spot — this matters more than anything

Where you place your kit decides 80% of your harvest. Pick a spot that meets all of these conditions:

High up — on top of a wardrobe, cupboard or shelf. Temperature is slightly higher up there, and away from foot-traffic and dust.

Living room or bedroom — clean, low-humidity rooms.

Indirect daylight — the kit needs a normal day/night rhythm, some daylight to know when to fruit, but never direct sun.

Stable temperature 21–24°C — the most important factor (see warning below).

Avoid: bathrooms (mould spores in the air), kitchens (cooking grease and contamination), windowsills (direct sun, cold drafts), and anywhere near a radiator (overheating).

Never on the floor — floors are cooler and dirtier than higher surfaces.

Reuse the cardboard box: After unpacking, put the grow bag with the kit back inside the original cardboard box, with the box open at the top. This blocks light from the sides and encourages mushrooms to grow on top of the cake instead of between the substrate and the plastic box (side pins)

Step 4 Get the temperature right

Ideal temperature: 23°C

Acceptable range: 21–24°C

Minimum: never below 20°C

Maximum: never above 27°C

Temperature is the single biggest reason FreshMushrooms kits succeed or fail. Psilocybe cubensis mycelium thrives in a narrow comfort zone:

21–24°C — the sweet spot. Pins appear in 1–2 weeks and mushrooms grow strong and dense.

Below 20°C — the mycelium goes into hibernation and basically stops growing. You will think your kit is broken when in reality it is just cold.

Above 27°C — the mycelium overheats and contamination risk skyrockets. Move the kit away from the heat source immediately.

Need extra warmth? Use a thermo heating mat

FreshMushrooms specific: the manufacturer recommends using the thermo mat only during the first few days of cultivation. Once the first pins appear and the room is warm enough, you can usually unplug the mat. Read our full guide on using a thermo mat for more detail.

Step 5 Wait for the first pins

Duration: 1–2 weeks (sometimes up to 3)

Watering: none — do not spray, do not soak

Bag position: opening tucked under the kit

First pins growing on a FreshMushrooms grow kit — step 5 illustration

For the first 1–2 weeks, just leave the kit alone. Do not water, do not spray the bag, do not open it. The mycelium needs the high humidity inside the closed bag to start forming pins (the tiny pinhead-sized mushrooms that grow into the real thing).

You will see small white or yellowish bumps appear on top of the cake. These are pins. Within a few days they will start to elongate and form tiny mushroom shapes.

Step 6 Stand the bag upright and let air in

Stand the FreshMushrooms grow bag upright once pins appear — step 6 illustration

Once the pins are clearly visible and the mushrooms are starting to grow upwards, it is time to give them room:

Stand the grow bag upright.

Open the top of the bag about 3–5 cm — not all the way, just enough for air exchange.

Fold the top of the bag down once and secure with the paperclips.

From this point on, the mushrooms grow fast — sometimes doubling in size in 24 hours. From now check the kit as often as you can.

Step 7 Harvest your mushrooms

Mature FreshMushrooms ready for harvest — veils about to break under the caps

When to harvest: just before the veil under the cap tears

How: twist and pull, do not yank

Yield: 200–300 g fresh mushrooms across all flushes (varies by strain)

When do you know it is harvest time?

This is the most important decision in the whole process. Harvest just before the thin veil membrane underneath the cap tears and the dark spore print starts to release. Visual cues:

The cap has opened up and flattened out from its closed bullet shape.

The veil underneath the cap is stretched thin but has not yet torn.

You can see the brown gills through the veil but no spore print on nearby surfaces yet.

Want to dive deeper? Read our full guide on when to harvest magic mushrooms for detailed photos, timing tips and common mistakes to avoid.

Step 8 Prepare for the next flush (cold shock)

FreshMushrooms kits produce 2–3 flushes. After your first harvest, do this:

Fill the grow box with clean, cold tap water right up to the top.
This is the cold shock — it tricks the mycelium into thinking a new fruiting cycle has begun and rehydrates the substrate.
Put the lid back on the box.
Use the original lid you saved from Step 1. Make sure it seals tight.
Let the kit rest for 12 hours.
Room temperature is fine. The fridge is even better if you have space.
Open one corner of the lid and drain the excess water.
Do not worry if very little water comes out — the substrate absorbs it. Then remove the lid completely.
Go back to Step 2 and repeat.
Place the kit back in the grow bag, follow the same flow. The second flush usually arrives a little slower than the first.

Why this works: the cold water rehydrates the dried-out substrate and the temperature drop signals the mycelium to start a new fruiting cycle. You can repeat this 2–3 times before the substrate is exhausted.

For a more detailed troubleshooting guide, see our FreshMushrooms grow tips article and the support article on optimising growth.

Pick your strain and start your own FreshMushrooms grow today. Browse all FreshMushrooms® XP grow kits.

Follow these FreshMushrooms grow kit instructions and you will get the most out of every kit. The most important things to remember are: keep the temperature at 23°C, never below 20°C, work clean, and harvest before the veil tears. Happy growing!