A cap assembly for a cultivation bottle for growing mushrooms is provided. The cap assembly (10) includes a bottle fitting member (20) configured to fit onto a mouth part (54) of the cultivation bottle (50) and a bowl-shaped member (30) configured to be placed on the bottle fitting member. The cap assembly being connected to the bottle prior to fruiting such that the mushrooms grow up through the mouth of the bottle and the attached cap assembly. The bowl-shaped member being separable from the bottle and attached bottle fitting member to facilitate harvesting of the mushroom fruiting bodies and removal of a section of the elongated hard tip portion.