The invention relates to a hydroponic greening element in particular for noise-protection walls in front of motorways, industrial installations and the like. It offers for the first time a greening element which, in the normal sequence of climatic events, meets its water requirement exclusively by natural precipitation and in the case of suitable plant cultivation, e.g. certain varieties of polygonum, requires no maintenance for years. Greening elements according to the invention can be arranged above one another in a storeyed manner on a noise-protection wall and then together use the natural precipitation, all upper and lower greening elements constantly having specifically the same water quantity available in their reservoirs. The water distribution takes place exclusively by means of force of gravity. Without regard for the position of the uppermost greening elements, the water supply remains pressureless; leaks cannot occur. Each greening element can be arranged longitudinally axially in the centre of the noise-protection wall and then greens the noise-protection wall both towards the noise source (motorway etc.) and towards the housing development to be protected, without a noise bridge arising as a result. <IMAGE>
