There can be several reasons.

1. The temperature is below 18°C. This means that the mushrooms do not grow in the average time. The mushrooms will still grow, but it will take days or even weeks longer. Try to keep the temperature at the lowest minimal at 18°C. 23°C is the optimal temperature.
2. The mycelium wasn’t fully developed when you have received the kit. This is not your fault in any case and also isn’t necessarily a bad thing. It just has to develop a little bit more and thus increasing the growth time by a couple of days. Nothing to worry about.

When nothing has happened with your myceliumbox for three weeks, we suggest you use the "Cold Shock" technique to kickstart the development of the mushrooms.

Here is how you do this:

Take the full grow kit as it is now (inside the closed grow bag) and put it in the refrigerator (2 - 7°C) for one night (8-12 hours). After this time, place the grow kit back on the original spot.

Within a few days, the mycelium should pop up the first pins.