A plant planting device and a planting method are disclosed. The plant planting apparatus includes a liquid reservoir and a planting apparatus. The liquid reservoir defines a liquid storage space for containing liquid. The planting apparatus is detachably mounted on the liquid reservoir and defines a planting space for accommodating a planting medium to cultivate a plant. The bottom of the planting apparatus is located above the liquid level of the liquid. In the present invention, the liquid reservoir is configured below the planting apparatus, in which the plant roots will extend downwardly into the liquid for self-absorbing water required for growth. Thus, there is no need of frequent watering, so as to enhance the convenience for people to take care of the cultivated plants.
